REVIEW www.rsc.org/npr|Natural Product Reports Molecules derived from the extremes of life Zoe E.Wilson and Margaret A.Brimble* Received 22nd August 2008 First published as an Advance Article on the weh 6th October 2008 D0:10.1039/b800164m Covering:up to early 2008 In order to survive extremes of pH.temperature.salinity and pressure.organisms have been found to develop unique defences against their environment,leading to the biosynthesis of novel molecules conditions Introduction 7.3 Lipids Brief history of the discovery of extremophiles Conclusions onof microorganisms found in extreme References Scope of this review High temperature 1 Introduction 2.3 Polyamin etab lites 1.1 Brief history of the discovery of extremophiles Nucleosides ydrate 26 Linids traditionally been considered life-supporting.Extreme-tolerant 261 Core lipids and fatty acids inke phosph olipid Although the first extremophilic organism.which was ther 3631 2.6.2.2 Ester-linked mophilic (heat-loving).was isolated in the 1860's.it was over 2.6.3 Lipoquinone extreme environments,leading to a rapid growth in research in 3.1 4 High pressure High salt group of whic e named arch Secondary metabolites 53 54 Osmolytes a molecular level,which led to Woese revising the natural axon 5 Carbohydrates inally it was thought that all archaea were extremophilic.bu 561 5.6.2 Glyco-and phospholipids (ether-linked) have shown that therere n which n hat all three 5.6.3 ugh to date 6.1 the most extreme conditions are inhabited by archaca.Review Carbohydrates have been published which discuss extremophile isol Lipids 7.1 Secondary metabolites 7.2 Carbohydrates 1.2 Classification of microorganisms found in extreme Traditionally,the extremes of life are considered to be high and low temperature.high pressure,high and low pH.and high salt. 441 Nat.Prod..Rep,2009,26,44-7刀 This journal isThe Royal Society of Chemistry 2009
Molecules derived from the extremes of life Zoe E. Wilson and Margaret A. Brimble* Received 22nd August 2008 First published as an Advance Article on the web 6th October 2008 DOI: 10.1039/b800164m Covering: up to early 2008 In order to survive extremes of pH, temperature, salinity and pressure, organisms have been found to develop unique defences against their environment, leading to the biosynthesis of novel molecules ranging from simple osmolytes and lipids to complex secondary metabolites. This review highlights novel molecules isolated from microorganisms that either tolerate or favour extreme growth conditions. 1 Introduction 1.1 Brief history of the discovery of extremophiles 1.2 Classification of microorganisms found in extreme environments 1.3 Scope of this review 2 High temperature 2.1 Secondary metabolites 2.2 Polyamines 2.3 Nucleosides 2.4 Osmolytes 2.5 Carbohydrates 2.6 Lipids 2.6.1 Core lipids and fatty acids 2.6.2 Glyco- and phospholipids 2.6.2.1 Ether-linked 2.6.2.2 Ester-linked 2.6.3 Lipoquinones 3 Low temperature 3.1 Secondary metabolites 4 High pressure 4.1 Secondary metabolites 4.2 Carbohydrates 5 High salt 5.1 Secondary metabolites 5.2 Polyamines 5.3 Nucleosides 5.4 Osmolytes 5.5 Carbohydrates 5.6 Lipids 5.6.1 Core lipids and fatty acids 5.6.2 Glyco- and phospholipids (ether-linked) 5.6.3 Lipoquinones 6 High pH 6.1 Secondary metabolites 6.2 Carbohydrates 6.3 Lipids 7 Low pH 7.1 Secondary metabolites 7.2 Carbohydrates 7.3 Lipids 8 Conclusions 9 References 1 Introduction 1.1 Brief history of the discovery of extremophiles A microorganism is classified as an extremophile if it grows optimally under conditions outside that which would have traditionally been considered life-supporting. Extreme-tolerant microorganisms in comparison can survive these harsh conditions, but grow best under more moderate conditions. Although the first extremophilic organism, which was thermophilic (heat-loving), was isolated in the 1860’s, it was over a century later that it began to be widely accepted that there were a significant number of organisms capable of surviving in extreme environments, leading to a rapid growth in research in this area.1 The term ‘‘extremophile’’ as a broad grouping for organisms which live optimally under extreme conditions was first proposed by MacElroy in 1974.2 Investigation of extreme environments led to the discovery of a novel group of microorganisms which were named archaeabacteria due to their primitive structures. These microorganisms were distinct from prokaryotes and eukaryotes on a molecular level, which led to Woese revising the natural taxonomy of life such that all living things were divided into one of three domains – the eucarya, the bacteria and the archaea.3 Originally it was thought that all archaea were extremophilic, but further studies have shown that there are in fact archaea which inhabit milder climates.4 It has been found that all three domains contain some examples of extremophilic organisms, though to date the most extreme conditions are inhabited by archaea. Reviews have been published which discuss extremophile isolation as well as some of the mechanisms which have been developed to combat the environments which these microorganisms inhabit.1,5,6 1.2 Classification of microorganisms found in extreme environments Traditionally, the extremes of life are considered to be high and low temperature, high pressure, high and low pH, and high salt. Department of Chemistry, University of Auckland, 23 Symonds St, Auckland, 1010, New Zealand. E-mail: m.brimble@auckland.ac.nz 44 | Nat. Prod. Rep., 2009, 26, 44–71 This journal is ª The Royal Society of Chemistry 2009 REVIEW www.rsc.org/npr | Natural Product Reports
Table 1 Classification of extremophiles Enzymes from extremophiles (sometimes called extrem ozymes) the terature since the Extremophile due hot topic in Thermophile icioofser there reumber of High temperature MPa(Im depth- 2 High temperature phile) Thermophiles were the first branch of extremophiles to be found, and are arguably the most have been isoated from from More recently some organisms have been classed as extrem any of the other classifications of extremophiles.Thermophilic es Io if ot better in the absence of they can not be in env nts whicha 2.1 Secondary metabolites grows optim The thresho 10 of scondary metgnro moph 53 orub from fication of an organism as extremophilic is included in the001 from a so sample in Pavia.Italy.was reported in 1964 Th Fow by Rothsc substance showed strong activity against Gram-positive bacteria less activity against Gram bacteria and little to no were used to guide classification.with microorganismsony being termed extremophilic if their optimal growth falls within these ranges 1.3 Scope of this reviev Margaret Brimble was born in Auckland.New Zealand.wher This review will focus on the structures of novel molecule derived from extremophilicor extreme-orant microorganisms which vith MS class (opt.)or tolerated (to) then awa included when this information is available.Fo PhD stud actor. 98 corth.New University of Sydney where she was promoted to R eted a BSe in I to New Zealand to take up the Chair in Org nic and and A BSe (Hons) natural products (especially shellfish aphthoquinone antibiotics.the garet Brimble in 2006 She is synthesis of a PhD for camcer She is currently President-Elect of mstry and wa named Zoe E.Wilon This joumal isThe Royal Society of Chemistry2009 Nat.Prod.Rep.2009.26.44-71145
More recently some organisms have been classed as extremophiles for being able to tolerate radiation or high concentrations of heavy metals, but as these organisms usually grow equally well if not better in the absence of these stresses they can not be considered to be true extremophiles.7 Many extremophilic organisms isolated to date actually thrive in environments which are extreme in two or more aspects, for example Thermoplasma acidophilum, a thermoacidophile, which grows optimally at 59 C and pH 1.0–2.0.8 The thresholds for what is considered to be extremophilic varies between publications. A good discussion of the problems inherent in the classi- fication of an organism as extremophilic is included in the 2001 review by Rothschild and Mancinelli.5 For the purpose of the present review the conditions in Table 1 were used to guide classification, with microorganisms only being termed extremophilic if their optimal growth falls within these ranges. 1.3 Scope of this review This review will focus on the structures of novel molecules derived from extremophilic or extreme-tolerant microorganisms. These microbial products will be classified according to which of the six extremophile classifications they fall under. The optimum (opt.) or tolerated (tol.) growth conditions of the source microorganism are included when this information is available. For classification purposes, if a microorganism falls under multiple classifications, it is grouped under the dominant environmental factor. Enzymes from extremophiles (sometimes called extremozymes) have been a hot topic in the literature since their discovery due to their significant potential for biotechnological applications. As a result of this interest there are a number of current reviews9–11 on their isolation and uses, and hence they will not be discussed in this review. 2 High temperature Thermophiles were the first branch of extremophiles to be found, and are arguably the most widely investigated extremophiles at the current time. Accordingly, significantly more novel molecules have been isolated from thermophilic microorganisms than from any of the other classifications of extremophiles. Thermophilic fungi have been found, and are seen to produce novel molecules as reported below; however, these microorganisms have much lower optimum growth temperatures than those observed for thermophilic bacteria or archaea.12 2.1 Secondary metabolites A range of secondary metabolites have been isolated from diverse thermophilic sources. The isolation of thermorubin, from a mildly thermophilic actinomycete (opt. 48–53 C) collected from a soil sample in Pavia, Italy, was reported in 1964. The substance showed strong activity against Gram-positive bacteria, less activity against Gram-negative bacteria and little to no activity against yeasts and fungi.13 The structure was originally reported14 in 1972 to contain xanthone and anthracene moieties; Table 1 Classification of extremophiles Extremophile Environmental factor Optimum growth conditions Thermophile High temperature 50–60 C (moderate thermophile) 61–79 C (thermophile) >80 C (hyperthermophile) Psychrophile Low temperature 35 MPa (1 m depth ¼ 10.5 kPa) Halophile High salt >3% NaCl Alkaliphile High pH pH >9 Acidophile Low pH pH <4 Zoe E: Wilson Zoe Wilson grew up in Warkworth, New Zealand, before moving to Auckland to attend the University of Auckland where she completed a BSc in 2005 and a BSc (Hons) in Medicinal Chemistry under the supervision of Professor Margaret Brimble in 2006. She is currently undertaking a PhD with Professor Brimble on the total synthesis of the extremophile natural product berkelic acid. Margaret A: Brimble Margaret Brimble was born in Auckland, New Zealand, where she was educated and graduated from the University of Auckland with an MSc (1st class) in chemistry. She was then awarded a UK Commonwealth Scholarship to undertake her PhD studies at Southampton University. In 1986 she was appointed as a lecturer at Massey University, NZ. After a brief stint as a visiting Professor at the University of California, Berkeley, she moved to the University of Sydney where she was promoted to Reader. In 1999, she returned to New Zealand to take up the Chair in Organic and Medicinal Chemistry at the University of Auckland, where her research program continues to focus on the synthesis of spiroacetalcontaining natural products (especially shellfish toxins), the synthesis of pyranonaphthoquinone antibiotics, the synthesis of alkaloids and peptidomimetics for the treatment of neurodegenerative disorders, and the synthesis of glycopeptides as components for cancer vaccines. She is currently President-Elect of the International Society of Heterocyclic Chemistry and was named the 2007 L’Ore´al–UNESCO For Women in Science Laureate for Asia–Pacific in Materials Science. This journal is ª The Royal Society of Chemistry 2009 Nat. Prod. Rep., 2009, 26, 44–71 | 45
owever,later physical and chemical studies showed thermor The therm philic fungus Streptomyces thermoviolaceus ssp pigens var.W -14 has been found to be a source not only of the molecules 4 and 5.Granaticin 2 and the novel derivative HO- 一NH thermorubin 1 O OH 。o& OH RCHOHCH 5 from Livingston Island,in the Antarctic.A novel alkaloid (microbiaeratin 12)and the known compound bacillamide hilic Actinomyces (strain CB21)from a 60C hot spring at Lake Tanganyika in Cape of TM-64 11. .(2 3-dihydroxybenzovlglycyl-thre -R Bacillus licheniformis cn Is pro activity in the specific condensing domain responsible for form- Thermozymocidin was isolated from strain IPV F-4333 of the CoCH a mildly thermophilicfungus Myceliasterilia(opt.40-45C)in 1972 show no a s high against Gram-positive e filamentous fungi and yeasts.The structure of was reported separately in 1972 as 10. also sep tely confirmed the of the cn The AnindeihatnraeiiBSl.asobteao dly therm ophilic soil actinomyceteTh be bis(2 hydroxyethyl)trisulfide.a compound whose synthesis was by total synthesis confirmed the structure of TM-64 11. ature om 0 BS114 461 Nat.Prod..Rep,2009,26,44-77 This journal isThe Royal Society of Chemistry009
however, later physical and chemical studies showed thermorubin to be oxanaphthacene 1. 15 The thermophilic fungus Streptomyces thermoviolaceus ssp. pigens var. WR-14 has been found to be a source not only of the previously isolated molecule granaticin 2, but also of the novel granaticin precursor dihydrogranaticin 3, and two related molecules 4 and 5. 16 Granaticin 2 and the novel derivative granaticinic acid 6 were later isolated from another thermophilic Streptomyces sp. XT-11989.17 Sibyllimycine (5,6,7,8-tetrahydro-3-methyl-8-oxo-4-azaindolizidine, 7) was isolated from a thermophilic Actinomyces (strain CB21) from a 60 C hot spring at Lake Tanganyika in Cape Banza, Africa.18 Siderophore SVK21 (2,3-dihydroxybenzoylglycyl-threonine, 8) was isolated from the thermoresistant (tol. 60 C) bacterium Bacillus licheniformis. SVK21 8 is a fragment of the known siderophore bacillibactin 9, which is produced by B. subtilis. SVK21 8 and bacillibactin 9 may be synthesized by the same enzyme in both bacteria, with the thermoresistant bacteria having disrupted activity in the specific condensing domain responsible for forming the cyclic trilactone.19 Thermozymocidin was isolated from strain IPV F-4333 of the mildly thermophilic fungusMycelia sterilia (opt. 40–45 C) in 1972. Thermozymocidin showed no activity against Gram-positive or Gram-negative bacteria but was highly active against a range of filamentous fungi and yeasts.20 The structure of thermozymocidin was reported separately in 1972 as 10. 21 Thermozymocidin 10 was also separately isolated from the thermophilic fungus Myriococcum albomyces and renamed myriocin. Synthetic studies confirmed the stereochemistry of the three stereogenic centres.22 The mildly thermophilic soil actinomycete Thermoactinomyces strain TM-64 (opt. 45 C) has been found to produce a thiazolecontaining alkaloid, TM-64.23 Structural elucidation24 followed by total synthesis25 confirmed the structure of TM-64 11. Strain IMBAS-11A of Microbispora aerate, a moderate thermophile (opt. 50 C), was isolated from penguin excrement from Livingston Island, in the Antarctic. A novel alkaloid (microbiaeratin 12) and the known compound bacillamide (referred to as microbiaeratinin) were isolated from this species. Structural elucidation showed microbiaeratin 12 to be the acetate of TM-64 11. 26 A novel carotenoid glycoside ester was isolated from the redpigmented moderately thermophilic (opt. 60 C)27 bacterium Meiothermus ruber in 1999. The structure of this carotenoid was determined to be 13 with the 600-position of the b-glucose acetylated by a series of 12 C10–C17 fatty acids, two of which were branched.28 A trisulfide with antitumor activity, BS-1, was isolated from the thermophile (opt. 68–70 C)29 Bacillus stearothermophilus UK563 in 1991.30 Structural elucidation showed BS-1 to be bis(2- hydroxyethyl)trisulfide 14, 31 a compound whose synthesis was reported in a 1942 patent32 but had never been isolated from nature.31 Further investigations indicated that BS-1 activates macrophages to the cytolytic stage.33 46 | Nat. Prod. Rep., 2009, 26, 44–71 This journal is ª The Royal Society of Chemistry 2009
Table 2 Cyclic polysulfides from Thermococcus species 2.2 Polyamines zation of nucleic Compound Core R at the 2.3 Nucleosides 23 nuc 7 26 B dM C.H CG西Ae 30 Porto Levante.Vulcano island.ItalyT.rcontained 3 the y omimG 59. lated from S highly fuorescent nucleoside S'-Deoxguanosine 60 was found to be produced by Ther de I This molee Novel nucleosides N27.4 61 and N31.4 62 were isolated from an w大6大 大 w8H大 putrescine40 spermidine 41 的并…甜 材m (w au4o货nwA2品a内m分 w方为 w caldoheptamine 52 homomhemonexamne This joumal isThe Royal Socety of Chemistry 2009 Nat.Prod.Rep,2009,.26,4471147
Cyclic polysulfides have been isolated from hyperthermophilic archaea of the sulfur-metabolising genus Thermococcus. Thermococcus tadjuricus (strain Ob9) from a marine hydrothermal system near Obock (Djibouti) and Thermococcus acidaminovorans (strain Vc6bk) from an Italian volcano were seen to produce a wide range of novel cyclic polysulfides (Table 2, 15–37) with four different polysulfide cores, as well as the known cyclic polysulfide lenthionine (1,2,3,5,6-pentathiepane, 38) 34,35 2.2 Polyamines Spermine 39, putrescine 40 and spermidine 41 are naturally occurring polyamines of which two or more are present in high concentrations in all growing cells, and are considered essential for cell proliferation.36,37 Investigation into the polyamine profiles of thermophilic microorganisms has led to the discovery of numerous novel polyamines (see Table 3), which are thought to play a role in the stabilization of nucleic acids at the extreme temperatures they inhabit.38 A recent review has been published on the polyamines of Thermus thermophilus. 39 2.3 Nucleosides Thermophiles have been found to contain novel nucleosides which are thought to play a role in stabilizing DNA against heat stresses by decreasing conformational flexibility.55 The isolation of four novel ribose-methylated nucleosides (55, 56, 57 and 58) was reported in 1987 from the thermohalophilic (opt. 87 C and pH 3.5–5)56,57 archaeon Sulfolobus solfataricus (previously Caldariella acidophilia41) and the thermophiles Thermoproteus neutrophilus (opt. 88 C)58 and Pyrodictium occultum (opt. 105 C) collected from a submarine solfataric field in the bay of Porto Levante, Vulcano island, Italy.59 T. neutrophilus contained all four nucleosides, S. solfataricus contained all but ac4 Cm 57 and P. occultum contained all but m2 2Gm 58. 60 That same year a novel derivative of the Y nucleoside, mimG 59, was also isolated from S. solfataricus. 56 This highly fluorescent nucleoside was also found in two other thermophilic archaea, Thermoproteus neutrophilus (opt. 88 C)58 and Pyrodictium occultum. 59,61 50 -Deoxyguanosine 60 was found to be produced by Thermoactinomycete sp. A6019 from a soil sample from Northwood, Rhode Island, USA. This molecule had previously been synthesized,62 but had not been isolated from a natural source.63 Novel nucleosides N27.4 61 and N31.4 62 were isolated from two thermophilic bacteria, Thermodesulfobacterium commune and Thermotoga maritima, and six thermophilic archaea, Table 2 Cyclic polysulfides from Thermococcus species Compound Core R1 R2 n Lenthionine 38 CH H — 15 A CH3 CH3 — 16 A C2H5 CH3 — 17 A i-C4H9 H — 18 A i-C4H9 CH3 — 19 A C2H5 i-C4H9 — 20 A i-C4H9 i-C3H7 — 21 A i-C4H9 i-C4H9 — 22 A Benzyl CH3 — 23 A Benzyl i-C4H9 — 24 A IndMe i-C4H9 — 25 B i-C4H9 CH3 — 26 B i-C4H9 i-C4H9 — 27 B IndMe i-C4H9 — 28 C i-C4H9 H — 29 C i-C4H9 CH3 — 30 C i-C4H9 i-C3H7 — 31 C i-C4H9 i-C4H9 — 32 C Benzyl i-C4H9 — 33 C IndMe i-C4H9 — 34 D i-C4H9 — 1 35 D CH3 — 2 36 D i-C4H9 — 2 37 D i-C4H9 — 3 This journal is ª The Royal Society of Chemistry 2009 Nat. Prod. Rep., 2009, 26, 44–71 | 47
Table3 Novel polyamines from various thermophile Polyamine Year Ref. Thermine 42 6 Hot spring at Mine.Japan >45 k a te ine 47 opropylagmatine4 .mutant and T.(opt 60C) Thermotoga maritima (opt.8C) andteatedsaioorsin 1 s Hocmombeote53ne4 Bacillus (opt.70C) Surface sediment froma Swiss lake 1992 51,54 2.4 Osmolyte An osmolyte is a small.highly soluble molecule which is either tes)play an importan ng c the c.With the trem n it is not surprising that a numb of nove H aroused considerable interest due to their potential biotechno 2 acCm 57 In 1983 methanophosphagen (2,3-cyclop rophosphoglycerate from the thermophilic (opt.65-70C) DnahdnoioLphosphate(di2.O,B-man0ryl 1.3'-isomer HO- m2Gm 58 mimG 59 bacteria,Thermotoga maritima and Thermotoga neapolitan a shallow submarine hot spring nea isus as well as two mesophilic archaea in and collected from hot sediments from a hydrothermal system near 00 0-P 日0 OH OH Ho义 OHOH OH 5'-deoxyguanosine 60 R:50h375副 di-mannosyl-di-myo-nositphosphate6 48|Nat.Prod.Rep,2009,26,44-71 This journal isThe Royal Society of Chemistry009
Pyrobaculum islandicum, Pyrodictium occultum, Thermococcus sp., Thermodiscus maritimus, Thermoproteus neutrophilus and Pyrococcus furiosus as well as two mesophilic archaea in 1992.64 2.4 Osmolytes An osmolyte is a small, highly soluble molecule which is either accumulated or synthesized by a cell. Osmolytes (also known as compatible solutes) play an important role in maintaining cell volume and fluid balance, without interfering with the central metabolism of the cell. With the increased stresses of extreme environments, it is not surprising that a number of novel osmolytes have been isolated from extremophiles. Novel osmolytes from extremophiles (also known as extremolytes) have aroused considerable interest due to their potential biotechnological uses in the protection of biological macromolecules and cells from damage by environmental changes.65,66 In 1983 methanophosphagen (2,3-cyclopyrophosphoglycerate 63) was isolated67,68 from the thermophilic (opt. 65–70 C) methanogen Methanobacterium thermoautotrophicus, which was collected from sewage sludge.69 Di-mannosyl-di-myo-inositol-phosphate (di-2-O-b-mannosyldi-myo-inositol-1,10 -phosphate 64) and the 1,30 -isomer of di-myo-inositol-phosphate (di-myo-inositol-1,30 -phosphate 65) were isolated from two thermophilic (opt. 80 C) Thermotoga bacteria, Thermotoga maritima and Thermotoga neapolitana, which were collected from a shallow submarine hot spring near Lucrino, Italy.52,70,71 Archaeoglobus fulgidus, a thermophilic (opt. 83 C) archaeon collected from hot sediments from a hydrothermal system near Table 3 Novel polyamines from various thermophiles Polyamine Isolation microorganism Microorganism source Year Ref. Thermine 42 Thermus thermophilus (opt. 65–72 C) Hot spring at Mine, Japan 1975 40,41 Thermospermine 43 1979 40,42 Caldopentamine 44 1982 40,43 Homocaldopentamine 45 1983 40,44 N4 -Bis(aminopropyl)norspermidine (a.k.a. tetrakis-3-aminopropyl)ammonium 46 1987 40,45 Thermopentamine 47 1990 40,46 N1 -Aminopropylagmatine 48 T. thermophilus disruption mutant 2005 47 N4 -(Aminopropyl)norspermidine 49 Thermoleophilum album and T. minutum (opt. 60 C) Hot springs at Arkansas, USA and Yellowstone National Park, Wyoming, USA 1990 48–50 N4 -(Aminopropyl)spermidine 50 N4 -Bis(aminopropyl)spermidine 51 1992 51 Caldoheptamine 52 Thermotoga maritima (opt. 80 C) Geothermally heated sea floors in Italy and the Azores 1986 52,53 Thermohexamine 53 Bacillus schlegelii (opt. 70 C) Surface sediment from a Swiss lake 1992 51,54 Homothermohexamine 54 48 | Nat. Prod. Rep., 2009, 26, 44–71 This journal is ª The Royal Society of Chemistry 2009
的6 odtoodae them Thermus thermophils(strain HB8)was found in 2005 to The structures of the components of the acid di-myinphosphate65 00 Fango,collected from arange of hot so were reported in The major teichoi units 74 and 75:however.it could not be determined in what i-yoero-phoschate ratio.The minor teichoic acid fraction TA2 showed a lot more 2.5 Carbohydrates 79(in order of decreasing abundance).The study was unable to determine whether these structures are present as a single,highly A series of novel polysaccharides have been isolated from and thei 2.6 Lipids 2.6.1 Cor Th In 190 an exopolysaccharide with the repeating unit67was the lipids isolated from other microorganisms.They contain 0r40 areinked rid ether inka to glyeerol or a polyol.rather than S.thermophilus strain SFil2,were reported in 1997.Later the e produced byS sisti revers istry to tha d in oth of branched he 0.a cidophilic At a similar reported in 2001. time,de Rosa et al.reported the isolation of "calditol".a nove 30-Gap-(1→3Hp0-G1-→3a-D-GalpNAc-1- [-D-Galp 68 p-D-Galp →2ul-Rnep(1-→2a-0Gap(1→3)a-0-Gcp1→3-a-DGap(1-→3aL-R3p1→ 69 Bo.Galp-1-→6jp-DGa →2-t-D-Galp-(1→3)--D-Galp(1-3-D-Gp1+3-L-Rh8p1→2-aL-Rh8p(1→ 70 B-D-Gal/2Aco -6f-D-Gap-(1-6)a-D-Gap-(1-3)f-L-Rhap(1-4)-p-D-Glcp(1-8)a-D-Gaf-(1-8)-p-D-Glcp-(1- -3-B-D-Cap(1-+3)-a-D-Gdlp(1--3-at-Rhap(1-2a-0-Galp(1- ai-Rhap 71 This joumal isThe Royal Society of Chemistry 2009 Nat.Prod..Rep,2009.26,44-71|49
Vulcano island, Italy, was found to produce the osmolyte di-glycerol-phosphate 66. 72–74 2.5 Carbohydrates A series of novel polysaccharides have been isolated from thermophilic microorganisms. Streptococcus thermophilus is a thermophilic (grows at 45 C but not at 15 C) bacteria isolated from yoghurt, cheese and their starter cultures.75 The species status of S. thermophilus has been widely debated. S. thermophilus was reclassified as Streptococcus salicarius ssp. thermophilus in 198476 before being reinstated as a species in 1991,75 which has been supported in the recent literature.77 In 1990 an exopolysaccharide with the repeating unit 67 was reported from S. thermophilus strains CNCMI 733, 734 and 735.78 The structures of a further two exopolysaccharide repeating units, 68 from S. thermophilus strain SFi39 and 69 from S. thermophilus strain SFi12, were reported in 1997.79 Later the same year, the exopolysaccharide produced by S. thermophilus strain OR 90 was reported, with the repeating unit consisting of branched heptasaccharide 70. 80 The repeating unit of the exopolysaccharide of S. thermophilus strain SE 71 was reported in 2001. This exopolysaccharide contains 0.4 equivalents of O-acetyl groups per repeating unit.81 Finally, a further exopolysaccharide, 72, from S. thermophilus strain EU20, was also reported in 2001.82 Thermus thermophilus60 (strain HB8) was found in 2005 to produce a novel polysaccharide 73, which consisted of a disaccharide repeating unit to which a trisaccharide chain is linked nonstoichiometrically.40,83 The structures of the components of the two teichoic acid fractions from the Gram-positive thermophilic (opt. 55–65 C) bacteria Geobacillis thermoleovorans (previously Bacillus thermoleovorans) 84 strain Fango, collected from a range of hot soil and mud samples, were reported in 2006.85,86 The major teichoic acid fraction TA1 was seen to consist of two different repeating units 74 and 75; however, it could not be determined in what ratio. The minor teichoic acid fraction TA2 showed a lot more variability. Although the major repeating units were the same as for TA1 (74 and 75), it also had the repeating units 76, 77, 78 and 79 (in order of decreasing abundance). The study was unable to determine whether these structures are present as a single, highly variable glycerol polymer with non-stoichiometric appendages or whether there are different chains which behave the same chromatographically.85 2.6 Lipids 2.6.1 Core lipids and fatty acids. The lipids of thermophilic archaea are characterized by three key structural differences to the lipids isolated from other microorganisms. They contain isoprenoid (phytanyl) chains with 15, 20, 25 or 40 carbons, rather than the straight chains of other organisms. Two of these chains are linked via ether linkages to glycerol or a polyol, rather than the ester linkage found elsewhere. The glycerol found in archaea, 2,3-di-O-sn-glycerol 80, has the reverse stereochemistry to that found in other organisms.87,88 Novel lipids have also been isolated from thermophilic microorganisms which contain the more traditional ester linkage. In 1974, Langworthy et al. reported the isolation of glycolipid B, a novel polyol of undetermined structure from the thermoacidophilic Solfolobus acidocaldarius strain 98.3.89 At a similar time, de Rosa et al. reported the isolation of ‘‘calditol’’, a novel This journal is ª The Royal Society of Chemistry 2009 Nat. Prod. Rep., 2009, 26, 44–71 | 49
→3Ga1-→3-GaINAc-(1- →10-G0-(3P→1Go(3P a-Glc(1->6)-a-ManNAc-(1->4)-a-Man-(1-4) →1)-Gro3pao-Gdp a-D-Gicp 73 74 75 76 →1-Go(3P →1-Gro-(3p →-o-3P w-D-GIcpNAc-(1-2)-u-O-Gkcp a-D-GICpNAc-(1-3)--D-Glcp 78 79 amounts of 111 and 112.These diols were found to be linked to glycan head groups,which were not fully character ture of the calditol from S.acidocaldarius to be 83which was dentcal to the calditol of s.as determined by HO A novel class of lipids (Table 4)was first isolated from ther moacidophiles in the 1970s.These molecules feature two C 108 10g ns wh OH dialkyl-calditol-tetraethers-GDNTs(as calditol was originally thought to be a nonito 11 85 ynthesist and the chains contain 04 evclopentaneg The polar lipids of archaea are typically substituted on the free hydroxyl group of the glycerol head group and have ber growtl may b nly An ontaining a“broken Cochain (f)has also beer ted The structure of a major glycolipid from Thermus oshima total lipid NTU-063 (opt.70C)isolated from Wu-rai hot springs,Tai- was sreported n B-Gicp-( 6P- eth Th the -acyl estr of the are mainly from C that GL-I of T.SPS-1 (from Portu X9 this study did not carbohydrate Also in2004 the major polar glycolipids of FU107 as ha ing me The novel fatty acid 15,16-dimethyl-30-glyceryloxy- (1-1-glycerol diester where the glycerol esters were mainly -and anteiso-branched C hydroxyl C laty nally Therm 4A3 )(opt.60 and opt.73showed the presence of novel ongchain -dio with one f three carbohvdrate backbones (AC).of 109(major component)and 110(minor component),as well as which the stereochemistry of the linkages was not determined. 501 Nat.Prod.Rep2009,26,44-71 This journal isThe Royal Society of Chemistry009
nonitol from the thermophile Solfolobus solfataricus (previously Caldariella acidophilia). Calditol was assigned a branched chain nonitol structure 81 with no stereochemistry determined.90 In 1995 the calditol of S. acidocaldarius was assigned the structure 82 by Sugai et al.91 Total synthesis in 1999 confirmed the structure of the calditol from S. acidocaldarius to be 8392 which was identical to the calditol of S. solfataricus, as determined by further studies.93 A novel class of lipids (Table 4) was first isolated from thermoacidophiles in the 1970s. These molecules feature two C40 isoprenoid chains which are linked to either two molecules of glycerol (the glycerol-dialkyl-glycerol-tetraethers – GDGTs) or to a molecule of glycerol and a molecule of calditol (glyceroldialkyl-calditol-tetraethers – GDNTs (as calditol was originally thought to be a nonitol (see above)). The alkyl chains were originally assigned an antiparallel orientation (84),99 but more recent studies have indicated that the diglycerol tetraethers may actually be present as a combination of regioisomers (84 + 85).100 The chirality of the C40 chains has been confirmed by total synthesis101 and the chains contain 0–4 cyclopentane groups (a–e), with the amount of cyclisation observed to increase as growth temperature rises.102 The two alkyl chains may be the same or different (see Table 4, 86–106). An isomer (101) containing a ‘‘broken’’ C40 chain (f) has also been isolated.97 A novel core lipid, FU, was isolated from the total lipid fraction of Methanothermus fervidus in 1998.103 Methanothermus fervidus is a hyperthermophilic (opt. 83 C) methanogen isolated from an Icelandic hot spring.104 The most likely structure for FU is a bridged version of GDGT (a + a) 107, although the exact position of the bridge has not been fully confirmed.103 The novel fatty acid 15,16-dimethyl-30-glyceryloxytriacontanoic acid 108 was isolated from a thermophilic (opt. 80 C) and mildly halotolerant (tol. 0.25–3.75% NaCl) strain of anaerobic bacteria isolated from geothermally heated sea floors in the Azores and Italy.52,105 Acid hydrolysis of the glycolipids of the thermophiles Thermus scotoductus X-1 (opt. 65 C)106 and Thermus filiformis Tok4 A2 (opt. 73 C)107 showed the presence of novel long-chain 1,2-diols, 109 (major component) and 110 (minor component), as well as trace amounts of 111 and 112. These diols were found to be linked to glycan head groups, which were not fully characterized.108 T. scotoductus X-1 was collected from hot tap water in Iceland and T. filiformis Tok4 A2 was collected from a hot spring in New Zealand.107 2.6.2 Glyco- and phospholipids. 2.6.2.1 Ether-linked The polar lipids of archaea are typically substituted on the free hydroxyl group of the glycerol head group and have been reviewed in the literature.87,109,110 Only the isolation of novel structures not included in these reviews will be discussed herein. The structure of a major glycolipid from Thermus oshimai NTU-063 (opt. 70 C)111 isolated from Wu-rai hot springs, Taiwan, was reported in 2004 to be b-Glcp-(1/6)-b-Glcp-(1/6)-bGlcp-NAcyl-(1/2)-a-Glcp-(1/1)-glycerol diester. The N-acyl group is either C15:0 or C17:0 and the O-acyl esters of the glycerol are mainly from C15:0–C18:0 including straight, isobranched and anteisobranched fatty acids.112 Previously it had been shown that GL-1 of T. oshimai SPS-11 (from Portuguese hot springs) has the same carbohydrate sequence and similar fatty acid composition,111,113 but this study did not determine the linkage or configuration, hence it cannot be claimed that they have identical carbohydrate moieties.112 Also in 2004 the major polar glycolipids of Meiothermus taiwanensis ATCC BAA-400 were reported as having the structure b-Galp-(1/6)-b-Galp-(1/6)-b-Gal-NAcyl-(1/2)-a-Gly- (1/1)-glycerol diester where the glycerol esters were mainly iso- and anteiso-branched C15:0 and C17:0 and the N-acyl is a C17:0 or hydroxyl C17:0 fatty acid.114 Glycolipids from a further four Meiothermus species, M. ruber, M. cerbereus, M. silvanus (originally Thermus silvanus) 115 and M. chliarophilus (originally Thermus chliarophilus) 115 (opt. 60 C,27 55 C,116 55 C117 and 50 C117 respectively) were reported in 1999. Each strain produced glycolipids with one of three carbohydrate backbones (A–C), of which the stereochemistry of the linkages was not determined, 50 | Nat. Prod. Rep., 2009, 26, 44–71 This journal is ª The Royal Society of Chemistry 2009
Table4 Tetracther lipids of archaea 人人)H8 HO OH -OH OHOHOHOHOHOHO HO ,H0 OH HO 2.3-di--sn-glycerol 80 81 R-OH GDGT H.-isoprenyl-0 H.o-isoprony- OH o-isoprenyl-H o-isoprenyt0 GDNT 84 85 人 GDGT/GDNT (isoprenyl chains) Year isolated Microorganism GDGT (a +a)86,GDGT (b+b)87,GDGT (e+e)88 1977 G,909D04 1980 GD DOTDT 198 Sulfolobus solfataricus cDTe·LCDNF 10 Thermoproteus tenax strain Kra-1 This joumal isThe Royal Society of Chemistry 2009 Nat.Prod..Rep,2009,26,44-7115T
Table 4 Tetraether lipids of archaea GDGT / GDNT (isoprenyl chains) Year isolated Microorganism GDGT (a + a) 86, GDGT (b + b) 87, GDGT (c + c) 88 1977 Solfolobus solfataricus (previously Caldariella acidophila) strain MT394,95 and Thermoplasma acidophilum (GDGT (a + a))96 GDGT (d + d) 89, GDGT (e + e) 90, GDNT (a + a) 91, GDNT (b + b) 92, GDNT (c + c) 93, GDNT (d + d) 94, GDNT (e + e) 95 1980 Solfolobus solfataricus strain MT490,95 GDGT (a + f) 96, GDGT (a + b) 97, GDGT (b + c) 98, GDGT (c + d) 99, GDGT (d + e) 100, GDNT (a + f) 101, GDNT (a + b) 102, GDNT (b + c) 103, GDNT (c + d) 104, GDNT (d + e) 105 1983 Sulfolobus solfataricus97 GDGT (a + c) 106 1988 Thermoproteus tenax strain Kra-198 This journal is ª The Royal Society of Chemistry 2009 Nat. Prod. Rep., 2009, 26, 44–71 | 51
Gkc-GIc-GaINR'.Glc-O-CHzCHRCH,R 9 Gkc-Gal-GaIWRGkc-O-CH-CHR>CH.R 9 Gkc-Gal-GIcNR'-Glc-O-CH.-CHR-CHaR GLla GL-lb Strain Backbone R'% R2(% R) R2% M ruber A 2.0HCm90 B 2.0HCm≥90 CeSol M.silvanus 2-0HC2n(83) C1s077 C10(6. M.chliarophils 2.0HC,m90 60(5. Cra (5) Ci (4. and showed two bands of glycolipids by thin layer chromatog Table 6 from a hot s which cont cosylin R he R3 Isoprenyl chains lyses in the pres GL-I B-Gulose + 120 群 Most abundant isoprenyl chain listed;see Table 4 for structures OH OH OH AG1113 2.6.2.2 Ester-linked.A novel glycolipid was isolated from the OH cture 一0-Ca4 OH hexadecanoyl)-(12)-Glcp digl ceride The structure of two myo-inositol- 0-C2H4 major glycolipids GLI 121 and GL2 122 and a phospholipid o-C20H41 o with most ab amu-S The th A114 115 mohalophilic strain Samu-SAl (opt.75C and%w NaCl) a5 m a depth of0m in a hot spring on Mount ated thermoacidophile (opt. ThePGLl 124d PGL212re 59C and pH 1.0-2.0)collected from a smoldering coal pile in isolated from the thermophiles Thermus oshimai NTU-063. 521 Nat.Prod.Rep2009,26,44-77 This journal isThe Royal Society of Chemistry009
and showed two bands of glycolipids by thin layer chromatography (GL-1a and GL-1b) due to differing substitution on the polar head group (see Table 5).118 M. cerbereus was first isolated from a hot spring in the Geysir geothermal region of Iceland.116 The isolation of two novel polar lipids AGI 113 and AI 114 from Aeropyrum pernix K1 which contained glucosylinositol as the polar head group was reported in 1999.119 Aeropyrum pernix is a hyperthermophilic (opt. 90–95 C) archaeon which was isolated from a coastal solfataric thermal vent off Kodakara-Jima Island, Japan.120 A structurally similar novel glycolipid 115 was isolated from the thermohalophilic (grows at up to 93 C and lyses in the presence of less than 3.5% NaCl) archaeon Thermococcus celer, which was collected from a marine water hole on Vulcano island, Italy.121,122 In 1999, the structures of five novel neutral glycolipids (116– 120, Table 6) were reported.123 These glycolipids had been isolated from Thermoplasma acidophilum, a thermoacidophile (opt. 59 C and pH 1.0–2.0) collected from a smoldering coal pile in the USA, and consisted of GDGTs which were substituted on one or both of the free hydroxyls.8 2.6.2.2 Ester-linked. A novel glycolipid was isolated from the thermophile (opt. 65–72 C) Thermus thermophilus (previously Flavobacterium thermophilum124) HB-8 in 1974. Its structure was determined to be Galf-(1/2)-Galp-(1/6)-GlcN(15-methylhexadecanoyl)-(1/2)-Glcp-diglyceride.125 The structure of two major glycolipids GL1 121 and GL2 122 and a phospholipid PGL 123 from T. thermophilus strain Samu-SA1 was published in 2006 (shown with most abundant chain lengths).126 The thermohalophilic strain Samu-SA1 (opt. 75 C and 2% w/v NaCl) was isolated from a depth of 60 m in a hot spring on Mount Grillo, Naples, Italy.127 The novel phosphoglycolipids PGL1 124 and PGL2 125 were isolated from the thermophiles Thermus oshimai NTU-063, Table 5 Glycolipids from Meiothermus species Strain Backbone GL-1a GL-1b R1 (%) R2 (%) R1 (%) R2 (%) M. ruber A 2-OH C17:0 (>90) C15:0 (89), C16:0 (3), C17:0 (8) C15:0 (30), 3-OH C15:0 (13), C17:0 (27), 3-OH C17:0 (30) C15:0 (91), C16:0 (3), C17:0 (8) M. cerbereus B 2-OH C17:0 >90) C15:0 (2), C16:0 (10), C17:0 (18) 3-OH C17:0 (>90) C15:0 (76), C16:0 (10), C17:0 (14) M. silvanus B 2-OH C17:0 (83), 2-OH C16:0 (12) C15:0 (75), C16:0 (5), C17:0 (20) C15:0 (43), C16:0 (10), C17:0 (42), 3-OH C17:0 (5) C15:0 (77), C16:0 (6), C17:0 (17) M. chliarophilus C 2-OH C17:0 (>90) C15:0 (74), C16:0 (5), C17:0 (20) C17:0 (>90) C15:0 (72), C16:0 (4), C17:0 (23) Table 6 Neutral glycolipids from Thermoplasma acidophilum Compound R1 R2 Isoprenyl chainsa 116 GL-1a b-Gulose OH b + b 117 GL-1b a-Glucose OH a + a 118 GL-2a b-Gulose b-Gulose b + b 119 GL-2b b-Gulose a-Glucose b + b 120 GL-2c a-Glucose a-Glucose b + b a Most abundant isoprenyl chain listed; see Table 4 for structures. 52 | Nat. Prod. Rep., 2009, 26, 44–71 This journal is ª The Royal Society of Chemistry 2009
8 HO HO OH OH HOHO GL112 G2122 PGL 12 Therms thermophilus NTU-077,Meiothermus ruber NTU-124 which were from hot springs in Taiwan.While PSL HO ructurally similar to a phospholy on-to he ratio of iso to ratio of PGL2 to PGLI increased with increasing culture emperature wo r iis a reddis -brown thermophilic(opt a Japanese hot pringThe lipid composition strain HLOS has been investigated and the dominant al lipic extrac were Ioun a to an 135 OH OR 29WaNcsesweepeetsminorcomponcntsTangingfiom 骨溜 tetra-o 131and derivatives 132 了adeg7 then lg小yce ides of B.acidocaldarius were partially characterized to be 134 OH 0=0 HO NH HO 0 PGL1 124 PGL2 125 This joumal isThe Royal Society of Chemistry 2009 Nat.Prod..Rep,2009.26,44-71|53
Thermus thermophilus NTU-077, Meiothermus ruber NTU-124 (originally Thermus ruber115) and Meiothermus taiwanensis NTU- 220 (opt. 70 C,111 65–72 C,40 60 C27 and 55 C128 respectively), which were collected from hot springs in Taiwan. While PGL1 124 is structurally similar to a phosphoglycolipid from the radiation-tolerant Deinococcus radiodurans, 129 PGL2 125 is the first phospholipid identified with a 2-acylalkyldio-1-O-phosphate moiety. The fatty acids were found to be mainly iso-branched C15:0, C16:0 and C17:0 and anteiso-branched C15:0 and C17:0 fatty acids with the ratio of iso to anteiso fatty acids increasing at higher culture temperatures. In all strains but T. oshimai, the ratio of PGL2 to PGL1 increased with increasing culture temperature.130 Two novel glycolipids 126 and 127 with the very rare a(1/4) diglucosyl structure were isolated from the thermophile Thermotoga maritima in 1992.131 Roseiflexus castenholzii is a reddish-brown thermophilic (opt. 50 C) bacteria which was isolated from a bacterial mat in a Japanese hot spring.132 The lipid composition of R. castenholzii strain HLO8T has been investigated and the dominant compounds in the total lipid extract were found to be alkane- 1,2-diol-based glycosides with the major isomers being 128 and 129. Wax esters were present as minor components ranging from 37 to 40 carbons in length.133 A novel Lipid A with the unique structure 130 was isolated from the Gram-negative thermophile Aquifex pyrophilus in 2000.134,135 Pentacyclic tetra-ol 131 and two glucosamine derivatives 132 and 133 were isolated from the glycolipid fraction of Bacillus acidocaldarius in 1976. In the same study the diglucosyl glycerides of B. acidocaldarius were partially characterized to be 134 This journal is ª The Royal Society of Chemistry 2009 Nat. Prod. Rep., 2009, 26, 44–71 | 53
