Single cell protein In a culture medium for the growth of heterotrophs what do you think the carbon: nitrogen(C: N)ratio should be? 10:1 C: N ratio The C N ratio should be about 10: 1. The organic carbon in the medium provides both a source of a sour。e of carbon Cells contain more carbon that nitrogen. The correct ratio of C: N is about 10: 1, although this differs slightly between organisms. This means that a medium containing 3%w/v sugar should be supplied with ammonia at about 0.3%w/v. At a C: N ratio of 1: 1 most of the ammonia would not be incorporated into cells(it is present in excess)and would be wasted. At C N ratios more than 10: 1 the ammonia would be completely used up before all the sugar, reducing the biomass output and wasting the sugar onid-substrate The cost of substrates used in sCP production may represent 40-75% of the total fermentations production cost. Ammonia contributes 5-15% of the substrate cost but the major portion is the carbon source. Atmospheric Co is free, but costly energy is needed for agitation to dissolve it into dense algal cultures. Wastes from agriculture and industry can be plentiful and relatively cheap, but may still represent 20-30% of the total production costs. Solid agricultural wastes, especially cellulosic ones, may also need expensive pre-treatment before they can be used in solid-substrate fermentations. Industrial wastes in the form of effluents can have high levels of BOd(Biological Oxygen Demand), which means they could cause pollution if disposed of in water without treatment Using themas substrates for sCP production can reduce the BOD by as much as 70-80% and so save on treatment costs. Such agricultural and industrial wastes are derived from biomass(plant material)which is renewable and likely to remain plentiful and relatively cheap Hydrocarbons and their derivatives can represent from 30-70% of total production costs. They are derived from oil or natural gas which are non-renewable, will not remain as plentiful as at present and will become increasing expensive. They also have alternative uses as fuels and petrochemicals and availability is often influenced by political issues 4.5 MIcro-organlsms for SCP production The physiological groups of organisms used in sCP production have been given in Table 4. 1. We have examined the characteristics an organism should and should not have in order to be suitable as food or feed in Section 43. When selecting an organism for a particularproduction process, factors relating to growth of the organism also need to be considered Listed below are characteristics in culture of an organism you are intending to use in an seP process you are developing. Consider whether each characteristic is an advantage or disadvantage to you. Tick the appropriate box, or if you think thecharacteristicis an advantage on the one hand but a disadvantage on the other tick both boxesSingle cell protein 67 CN ratio ~lii-aubstrate fermentations renewable In a culture medium for the growth of heterotrophs what do you think the n carbon : nitrogen (CN) ratio should be? 1:l 1O:l 1oo:l 1Ooo:l The CN ratio should be about 101. The organic carbon in the medium provides both a source of energy and a source of carbon. Cells contain more carbon that nitrogen. The correct ratio of CN is about lO:l, although this differs slightly between organisms. This means that a medium containing 3% w/v sugar should be supplied with ammonia at about 0.3% w/v. At a CN ratio of 1:l most of the ammonia would not be incorporated into cells (it is present in excess) and would be wasted. At CN ratios more than 10:l the ammonia would be completely used up before all the sugar, ducing the biomass output and wasting the sugar. The cost of substrates used in SCF' production may represent 40-7596 of the total production cost. Ammonia contributes 515% of the substrate cost but the major portion is the carbon source. Atmospheric COZ is free, but costly energy is needed for agitation to dissolve it into dense algal cultures. Wastes from agriculture and industry can be plentiful and relatively cheap, but may still re resent 20-3096 of the total roduction pretreatment before they can be used in solid-substrate fermentations. Industrial wastes in the form of effluents can have high levels of BOD (Biological Oxygen Demand), which means they could cause pollution if disposed of in water without treatment Using them as substrates for XP production can reduce the BOD by as much as 70-801 and so save on treatment costs. Such agricultural and industrial wastes are derived from biomass (plant material) which is renewable and likely to remain plentiful and relatively cheap. Hydrocarbons and their derivatives can represent from 3G7096 of total production costs. They are derived from oil or natural gas which are non-renewable, will not remain as plentiful as at present and will become increasingly expensive. They also have alternative uses as fuels and petrochemicals and their availability is often influenced by political issues. costs. Solid agricultural wastes, especially ce 2 ulosic ones, may also n ee8 expensive 4.5 Micro-organisms for SCP production The physiological gruups of organisms used in XP production have been given in Table 4.1. We have exarmned ' the characteristics an organism should and should not have in order to be suitable as food or feed in Section 4.3. When selecting an organism for a particular production process, factors relating to growth of the organism also need to be considered. Listed below are characteristics in culture of an organism you are intending to use in an s8 process you are developing. Consider whether each characbistic is an advantage or disadvantage to you. Tick the appm riate box, or if you think tick both boxes. n the characteristic is an advantage on the one hand but a B 'sadvantage on the other