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.2009.26.44-71145More recently some organisms have been classed as extrem￾ophiles 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 publica￾tions. 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 micro￾organism 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 extrem￾ozymes) 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 <20
C Piezophile (barophile) High pressure >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 Wark￾worth, 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 Mar￾garet Brimble in 2006. She is currently undertaking a PhD with Professor Brimble on the total synthesis of the extrem￾ophile 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 awar￾ded a UK Commonwealth Scholarship to undertake her PhD studies at Southampton University. In 1986 she was appointed as a lecturer at Mas￾sey 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 spiroacetal￾containing natural products (especially shellfish toxins), the synthesis of pyranonaphthoquinone antibiotics, the synthesis of alkaloids and peptidomimetics for the treatment of neurodegener￾ative disorders, and the synthesis of glycopeptides as components for cancer vaccines. She is currently President-Elect of the Inter￾national 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