Metabolism of glycerol by mature boar spermatozoa.

Mature boar spermatozoa oxidized glycerol to carbon dioxide in the absence of any detectable activity of glycerol kinase. With triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase inhibited by the presence of 3-chloro-1-hydroxypropanone (CHOP), dihydroxyacetone phosphate accumulated in incubates when glycerol-3-phosphate was the substrate, but not when it was glycerol. Both dihydroxyacetone and glyceraldehyde could be used as substrates; in the presence of CHOP, dihydroxyacetone phosphate and fructose-1,6-bisphosphate accumulated when dihydroxyacetone was the substrate, but not when it was glyceraldehyde. The metabolic pathways glycerol----glyceraldehyde----glyceraldehyde 3-phosphate and dihydroxyacetone----dihydroxyacetone phosphate have been shown to operate in these cells.     

Continuous culture of Candida boidinii variant 60 growing on methanol

Summary A new variant, Candida boidinii variant 60, which is less sensitive to methanol and formaldehyde shocks was grown in continuous cultures with methanol as sole carbon source. The substrate concentration in the feeding medium was either 1% methanol or 3% methanol. Biomass production, methanol consumption, the formation of formaldehyde and gas exchange were measured at different dilution rates. With low methanol feeding (10 g/l) maximal productivity of 0.44 g biomass/l·h is obtained at a dilution rate of 0.14 h^–1. Maximal specific growth rate is 0.18 h^–1. A yield of 0.32 g biomass/g methanol was obtained and the respiration quotient was determined as 0.55. Independently of initial substrate concentration, biomass decreases if methanol and formaldehyde are accumulating in the culture broth.In the culture with high methanol feeding (30 g/l) cell concentratioon increases up to 9 g/l at D=0.04 h^–1. At higher dilution rates methanol and form-aldehyde appear in the medium. Formaldehyde is then preferably oxidized without energy advantages for the cells. It seems that this enables the cells to overcome toxic effects caused by methanol and formaldehyde.     

Cybernetic modeling based on pathway analysis for Penicillium chrysogenum fed-batch fermentation

A macrokinetic model employing cybernetic methodology is proposed to describe mycelium growth and penicillin production. Based on the primordial and complete metabolic network of Penicillium chrysogenum found in the literature, the modeling procedure is guided by metabolic flux analysis and cybernetic modeling framework. The abstracted cybernetic model describes the transients of the consumption rates of the substrates, the assimilation rates of intermediates, the biomass growth rate, as well as the penicillin formation rate. Combined with the bioreactor model, these reaction rates are linked with the most important state variables, i.e., mycelium, substrate and product concentrations. Simplex method is used to estimate the sensitive parameters of the model. Finally, validation of the model is carried out with 20 batches of industrial-scale penicillin cultivation.     

Growth characteristics and oxidative capacity of<Emphasis Type="Italic"> Acetobacter aceti</Emphasis> IFO 3281: implications for <Emphasis Type="SmallCaps">l</Emphasis>-ribulose production

We studied the growth characteristics and oxidative capacities of Acetobacter aceti IFO 3281 in batch and chemostat cultures. In batch culture, glycerol was the best growth substrate and growth on ethanol occurred only after 6 days delay, although ethanol was rapidly oxidized to acetic acid. In continuous culture, both glycerol and ethanol were good growth substrates with similar characteristics. Resting cells in a bioreactor oxidized ribitol to l-ribulose with a maximal specific rate of 1.2 g g^–1 h^–1). The oxidation of ribitol was inhibited by ethanol but not by glycerol. Biomass yield (Y_SX; C-mmol/C-mmol) on ethanol and glycerol was low (0.21 and 0.17, respectively). In the presence of ribitol the yield was somewhat higher (0.25) with ethanol but lower (0.13) with glycerol, with respectively lower and higher CO₂ production. In chemostat cultures the oxidation rate of ribitol was unaffected by ethanol or glycerol. Cell-free extract oxidized ethanol very slowly but not ribitol; the oxidative activity was located in the cell membrane fraction. Enzymatic activities of some key metabolic enzymes were determined from steady-state chemostat with ethanol, glycerol, or ethanol/glycerol mixture as a growth limiting substrate. Based on the measured enzyme activities, metabolic pathways are proposed for ethanol and glycerol metabolism.     

Synergistic metabolism of a broad range of C1 compounds in the marine methylotrophic bacterium HTCC2181

The 1.3 Mbp genome of HTCC2181, a member of the abundant OM43 clade of coastal bacterioplankton, suggested it is an obligate methylotroph. Preliminary experiments demonstrated that methanol and formaldehyde, but not other common C1 compounds such as methylamine, could support growth. Methanol concentrations in seawater are reportedly < 100 nM, suggesting either that the flux of methanol through plankton pools is very rapid, or that methanol may not be the primary growth substrate for HTCC2181. Therefore, we investigated the apparent extreme substrate range restriction of HTCC2181 in greater detail. Growth rate and maximum cell density of HTCC2181 increased with methanol concentration, yielding a K(s) value of 19 μM. In contrast, no growth was observed in the presence of the methylated (C1) compounds, methyl chloride, trimethylamine-oxide (TMAO) or dimethylsulfoniopropionate (DMSP) when they were the sole substrates. However, growth rate, maximum cell density and cellular ATP content were significantly enhanced when any of these methylated compounds were provided in the presence of a limiting concentration of methanol. These observations fit a model in which the metabolic intermediate formaldehyde is required for net carbon assimilation, allowing C1 substrates that do not produce a formaldehyde intermediate to be oxidized for energy, but not assimilated into biomass. Rates of methanol and TMAO oxidation and assimilation were measured with (14)C-radiolabelled compounds in cultures of HTCC2181 and seawater microbial communities collected off the Oregon coast. The results indicated that in nature as well as in culture, C1 substrates are partitioned between those that are mainly oxidized to produce energy and those that are assimilated. These findings indicate that the combined fluxes of C1 compounds in coastal systems are sufficient to support significant populations of obligate methyltrophs by a metabolic strategy that involves the synergistic metabolism of multiple C1 compounds.     

重组巴氏毕赤酵母恒化培养动力学及代谢迁移特性研究

通过对甲醇营养型毕赤酵母基因工程菌以碳源甘油为限制性基质进行恒化培养动力学试验 ,结果认为 :(1 )细胞光密度与其干、湿重呈线性关系 ,当细胞光密度 (OD60 0 )为 1 0 0时细胞湿重 (WCW)为 1 2 8 3g L ,细胞干重 (WDW)则为 2 2 9g L ;(2 )基因工程菌P .pastoris的生长与限制性基质甘油残留浓度的关系符合Monod关系式 ,通过 1 μ对 1 S进行线性回归得 μmax=0 .366h- 1,Ks=0 .1 82 3g L ,经参数推导甘油最大菌体得率系数YG =0 .54g g ,菌体维持生长消耗底物系数m =0 .0 0 69g (g·h) ;氧最大菌体系数YX O2 =30 .96g moL ,菌体维持生长时消耗氧系数mO2 =0 .0 0 0 8mol (g·h) ,最适理论稀释速率Dm =0 .341h- 1;(3)从氨水的消耗速率和呼吸商 (RQ)的变化认为随着比生长速率 (μ)的增大 ,甘油代谢流从糖原异生和磷酸戊糖途径线性地向糖酵解和三羧酸循环途径进行代谢迁移 ,即糖酵解和三羧酸循环途径的代谢流量在线性地增大     

Macrokinetic model for Gluconobacter oxydans in 2-keto-L-gulonic acid mixed culture

A set of kinetic models have been developed for the production of 2-keto-L-gulonic acid from L-sorbose by a mixed culture of Gluconobacter oxydans and Bacillus megaterium. A metabolic pathway is proposed for Gluconobacter oxydans, and a macrokinetic model has been developed for Gluconobacter oxydans, where the balances of some key metabolites, ATP and NADH are taken into account. An unstructured model is proposed for concomitant bacterium Bacillus megaterium. In the macrokinetic model and unstructured model, the mechanism of interaction between Gluconobacter oxydans and Bacillus megaterium is investigated and modeled. The specific substrate uptake rate and the specific growth rate obtained from the macrokinetic model are then coupled into a bioreactor model such that the relationship between the substrate feeding rate and the main state variables, such as the medium volume, the biomass concentrations, the substrate, and the is set up. A closed loop regulator model is introduced to approximate the induction of enzyme pool during lag phase after inoculation. Experimental results demonstrate that the model is able to describe 2-keto-L-gulonic acid fermentation process with reasonable accuracy.     

A rational approach to improving productivity in recombinant Pichia pastoris fermentation

A Mut(S) Pichia pastoris strain that had been genetically modified to produce and secrete sea raven antifreeze protein was used as a model system to demonstrate the implementation of a rational, model-based approach to improve process productivity. A set of glycerol/methanol mixed-feed continuous stirred-tank reactor (CSTR) experiments was performed at the 5-L scale to characterize the relationship between the specific growth rate and the cell yield on methanol, the specific methanol consumption rate, the specific recombinant protein formation rate, and the productivity based on secreted protein levels. The range of dilution rates studied was 0. 01 to 0.10 h(-1), and the residual methanol concentration was kept constant at approximately 2 g/L (below the inhibitory level). With the assumption that the cell yield on glycerol was constant, the cell yield on methanol increased from approximately 0.5 to 1.5 over the range studied. A maximum specific methanol consumption rate of 20 mg/g. h was achieved at a dilution rate of 0.06 h(-1). The specific product formation rate and the volumetric productivity based on product continued to increase over the range of dilution rates studied, and the maximum values were 0.06 mg/g. h and 1.7 mg/L. h, respectively. Therefore, no evidence of repression by glycerol was observed over this range, and operating at the highest dilution rate studied maximized productivity. Fed-batch mass balance equations, based on Monod-type kinetics and parameters derived from data collected during the CSTR work, were then used to predict cell growth and recombinant protein production and to develop an exponential feeding strategy using two carbon sources. Two exponential fed-batch fermentations were conducted according to the predicted feeding strategy at specific growth rates of 0.03 h(-1) and 0.07 h(-1) to verify the accuracy of the model. Cell growth was accurately predicted in both fed-batch runs; however, the model underestimated recombinant product concentration. The overall volumetric productivity of both runs was approximately 2.2 mg/L. h, representing a tenfold increase in the productivity compared with a heuristic feeding strategy.     

Glyceraldehyde-3-phosphate, a glycolytic intermediate, plays a key role in controlling cell fate via inhibition of caspase activity

Glyceraldehyde-3-phosphate is a key intermediate in several central metabolic pathways of all organisms. Aldolase and glyceraldehyde-3-phosphate dehydrogenase are involved in the production or elimination of glyceraldehyde-3-phosphate during glycolysis or gluconeogenesis, and are differentially expressed under various physiological conditions, including cancer, hypoxia, and apoptosis. In this study, we examine the effects of glyceraldehyde-3-phosphate on cell survival and apoptosis. Overexpression of aldolase protected cells against apoptosis, and addition of glyceraldehyde-3-phosphate to cells delayed apoptosis. Additionally, delayed apoptotic phenomena were observed when glyceraldehyde-3-phosphate was added to a cell-free system, in which artificial apoptotic process was induced by adding dATP and cytochrome c. Surprisingly, glyceraldehyde-3-phosphate directly suppressed caspase-3 activity in a reversible noncompetitive mode, preventing caspase-dependent proteolysis. Based on these results, we suggest that glyceraldehyde-3-phosphate, a key molecule in several central metabolic pathways, functions as a molecule switch between cell survival and apoptosis.     

A kinetic analysis of hybridoma growth and metabolism in batch and continuous suspension culture: effect of nutrient concentration, dilution rate, and pH

Hybridomas are finding increased use for the production of a wide variety of monoclonal antibodies. Understanding the roles of physiological and environmental factors on the growth and metabolism of mammalian cells is a prerequisite for the development of rational scale-up procedures. An SP2/0-derived mouse hybridoma has been employed in the present work as a model system for hybridoma suspension culture. In preliminary shake flask studies to determine the effect of glucose and glutamine, it was found that the specific growth rate, the glucose and glutamine metabolic quotients, and the cumulative specific antibody production rate were independent of glucose concentration over the range commonly employed in cell cultures. Only the specific rate of glutamine uptake was found to depend on glutamine concentration. The cells were grown in continuous culture at constant pH and oxygen concentration at a variety of dilution rates. Specific substrate consumption rates and product formation rates were determined from the steady state concentrations. The specific glucose uptake rate deviated from the maintenance energy model(1) at low specific growth rates, probably due to changes in the metabolic pathways of the cells. Antibody production was not growth-associated; and higher specific antibody production rates were obtained at lower specific growth rates. The effect of pH on the metabolic quotients was also determined. An optimum in viable cell concentration was obtained between pH 7.1 and 7.4. The viable cell number and viability decreased dramatically at pH 6.8. At pH 7.7 the viable cell concentration initially decreased, but then recovered to values typical of pH 7.1-7.4. Higher specific nutrient consumption rates were found at the extreme pH values; however, glucose consumption was inhibited at low pH. The pH history also influenced the behavior at a given pH. Higher antibody metabolic quotients were obtained at the extreme pH values. Together with the effect of specific growth rate, this suggests higher antibody production under environmental or nutritional stress.     

A kinetic analysis of hybridoma growth and metabolism in batch and continuous suspension culture: effect of nutrient concentration, dilution rate, and pH. Reprinted from Biotechnology and Bioengineering, Vol. 32, Pp 947-965 (1988)

Hybridomas are finding increased use for the production of a wide variety of monoclonal antibodies. Understanding the roles of physiological and environmental factors on the growth and metabolism of mammalian cells is a prerequisite for the development of rational scale-up procedures. An SP2/0-derived mouse hybridoma has been employed in the present work as a model system for hybridoma suspension culture. In preliminary shake flask studies to determine the effect of glucose and glutaminE, it was found that the specific growth rate, the glucose and glutamine metabolic quotients, and the cumulative specific antibody production rate were independent of glucose concentration over the range commonly employed in cell cultures. Only the specific rate of glutamine uptake was found to depend on glutamine concentration. The cells were grown in continuous culture at constant pH and oxygen concentration at a variety of dilution rates. Specific substrate consumption rates and product formation rates were determined from the steady state concentrations. The specific glucose uptake rate deviated from the maintenance energy model(1) at low specific growth rates, probably due to changes in the metabolic pathways of the cells. Antibody production was not growth-associated; and higher specific antibody production rates were obtained at lower specific growth rates. The effect of pH on the metabolic quotients was also determined. An optimum in viable cell concentration was obtained between pH 7.1 and 7.4. The viable cell number and viability decreased dramatically at pH 6.8. At pH 7.7 the viable cell concentration initially decreased, but then recovered to values typical of pH 7.1-7.4. Higher specific nutrient consumption rates were found at the extreme pH values; however, glucose consumption was inhibited at low pH. The pH history also influenced the behavior at a given pH. Higher antibody metabolic quotients were obtained at the extreme pH values. Together with the effect of specific growth rate, this suggests higher antibody production under environmental or nutritional stress.     

Physiological responses of a methylotrophic bacterium after sudden shifts from C-limited chemostat to C-excess batch growth conditions

The response of steady-state continuous cultures of Methylobacterium sp. RXM to the addition of methanol pulses was studied. The increase of methanol concentration in the medium did not result in cell death under any of the conditions tested. When the growth rate of the steady-state cultures was low ( D = 0.046 h⁻¹), the specific growth rate increased. When the concentration of methanol in the pulse was increased from 36 mmol l⁻¹ to 280 mmol l⁻¹, uncoupled growth occurred and the molar cell yield decreased. Conversely, steady-state cultures at high growth rate ( D = 0.2 h⁻¹) showed a decrease in both specific growth rate and molar cell yield after the addition of the methanol pulses (32 and 164 mmol 1⁻¹). For all conditions, formaldehyde and formate were excreted into the medium but the levels did not exceed 1.13 mmol 1⁻¹ Slow-growing cultures were characterized by cells with high derepressed specific activities of methanol dehydrogenase and low specific activities of formaldehyde and formate dehydrogenases, fast-growing cells had lower specific activity for methanol dehydrogenase and higher activities of formaldehyde and formate dehydrogenases, resulting in the excretion of lower concentrations of formaldehyde and formate.
It is concluded that slow-growing cultures are more stable than fast-growing cultures for low methanol concentration fluctuations, and it is expected that maximum growth yields throughout the fermentation time are better achieved under the former conditions. However, for large fluctuations in the substrate concentration, the bacterial metabolic responses were identical both for slow-growing and fast-growing cultures.     

Metabolic aspects of the growth of a pink-pigmented facultative methylotroph in carbon-limited chemostat culture

Summary The regulation of carbon metabolism in a pink-pigmented facultative methylotroph has been studied. In methanol-limited chemostat culture a pH optimum at 7.0 with a narrow growth rate optimum with respect to growth yield and metabolic uncoupling was revealed. The average growth yield was 14±0.036 g·mol^–1 and the organism displayed a low maintenance energy and high maximum specific growth rate. When the carbon concentration in the feed remained constant and the dilution rate increased a deviation from linearity between substrate consumption and growth rate was found at higher growth rates. The addition of a pulse of methanol to a carbon-limited culture showed that anabolism could be dissociated from catabolism with the resulting accumulation of formaldehyde in concentrations which were not lethal. Offprint requests to: F. M. Girio     

In silico aided metabolic engineering of Saccharomyces cerevisiae for improved bioethanol production

In silico genome-scale cell models are promising tools for accelerating the design of cells with improved and desired properties. We demonstrated this by using a genome-scale reconstructed metabolic network of Saccharomyces cerevisiae to score a number of strategies for metabolic engineering of the redox metabolism that will lead to decreased glycerol and increased ethanol yields on glucose under anaerobic conditions. The best-scored strategies were predicted to completely eliminate formation of glycerol and increase ethanol yield with 10%. We successfully pursued one of the best strategies by expressing a non-phosphorylating, NADP(+)-dependent glyceraldehyde-3-phosphate dehydrogenase in S. cerevisiae. The resulting strain had a 40% lower glycerol yield on glucose while the ethanol yield increased with 3% without affecting the maximum specific growth rate. Similarly, expression of GAPN in a strain harbouring xylose reductase and xylitol dehydrogenase led to an improvement in ethanol yield by up to 25% on xylose/glucose mixtures.     

Mixed feeds of glycerol and methanol can improve the performance of Pichia pastoris cultures: A quantitative study based on concentration gradients in transient continuous cultures

Transient continuous cultures constitute a means to speed up strain characterization, by avoiding the need for many time-consuming steady-state experiments. In this study, mixed substrate growth on glycerol and methanol of a Pichia pastoris strain expressing and secreting recombinant avidin was characterized quantitatively by performing a nutrient gradient with linear increase of the methanol fraction in the feed medium from 0.5 to 0.93 C-mol C-mol(-1) at a dilution rate of 0.06 h(-1). The influence of the methanol fraction in the feed medium on recombinant avidin productivity and on specific alcohol oxidase activity were also examined. Results showed that, compared with cultures on methanol as sole carbon source, the specific recombinant avidin production rate was the same provided the methanol fraction in the feed medium was higher than 0.6 C-mol C-mol(-1). The volumetric avidin production rate was even 1.1-fold higher with a methanol fraction in the feed medium of 0.62 C-mol C-mol(-1) as a result of the higher biomass yield on mixed substrate growth compared with methanol alone. Moreover, since heat production and oxygen uptake rates are lower during mixed substrate growth on glycerol and methanol, mixed substrate cultures present technical advantages for the performance of high cell density P. pastoris cultures. Results obtained in a high cell density fed-batch culture with a mixed feed of 0.65 C-mol C-mol(-1) methanol and 0.35 C-mol C-mol(-1) glycerol were in agreement with results obtained during the transient nutrient gradient.     

Metabolic flux analysis for recombinant protein production by Pichia pastoris using dual carbon sources: Effects of methanol feeding rate

The intracellular metabolic fluxes through the central carbon pathways in the bioprocess for recombinant human erythropoietin (rHuEPO) production by Pichia pastoris (Mut⁺) were calculated to investigate the metabolic effects of dual carbon sources (methanol/sorbitol) and the methanol feed rate, and to obtain a deeper understanding of the regulatory circuitry of P. pastoris, using the established stoichiometry‐based model containing 102 metabolites and 141 reaction fluxes. Four fed‐batch operations with (MS‐) and without (M‐) sorbitol were performed at three different constant specific growth rates (h^?1), and denoted as M‐0.03, MS‐0.02, MS‐0.03, and MS‐0.04. Considering the methanol consumption pathway, the M‐0.03 and MS‐0.02 conditions produced similar effects and had >85% of formaldehyde flux towards the assimilatory pathway. In contrast, the use of the dual carbon source condition generated a shift in metabolism towards the dissimilatory pathway that corresponded to the shift in dilution rate from MS‐0.03 to MS‐0.04, indicating that the methanol feed exceeded the metabolic requirements at the higher µ₀. Comparing M‐0.03 and MS‐0.03 conditions, which had the same methanol feeding rates, sorbitol addition increased the rHuEPO synthetic flux 4.4‐fold. The glycolysis, gluconeogenesis, and PPP pathways worked uninterruptedly only at MS‐0.02 condition. PPP and TCA cycles worked with the highest disturbances at MS‐0.04 condition, which shows the stress of increased feeding rates of methanol on cell metabolism. Biotechnol. Bioeng. 2010; 105: 317–329. © 2009 Wiley Periodicals, Inc.     

Regulation of alcohol oxidase of a recombinant Pichia pastoris Mut+ strain in transient continuous cultures

In the methylotrophic yeast Pichia pastoris, alcohol oxidase (AOX) is a key enzyme involved in the dissimilation of methanol. Heterologous proteins are usually expressed under the control of the AOX1 promoter, which drives the expression of alcohol oxidase 1 in the wild-type strain. This study investigates the regulation of the alcohol oxidase enzyme of a recombinant P. pastoris Mut+ strain in cultures on glycerol and methanol as sole carbon sources and in mixed substrate cultures on both substrates. The aim was to have a better insight in the transition from growth on glycerol to growth on methanol, which is a key step in standard high cell density P. pastoris cultures for the production of foreign proteins. Nutrient shifts in chemostat cultures showed that after growth on glycerol use of mixed feeds of glycerol and methanol allowed faster induction of alcohol oxidase and faster adaptation of cellular metabolism than with a feed containing methanol as sole carbon source. The results of this study showed also how critical it is to avoid transient methanol accumulation during P. pastoris cultures operated at low residual methanol concentrations. Indeed, pulse experiments during chemostat cultures showed that sudden increase in methanol concentrations in cultures performed under methanol-limited or dual methanol and glycerol-limited growth conditions leads to wash-out of the culture because of too high consumption rate of methanol, which leads to excretion of toxic intermediates. High rate of methanol consumption was due to high specific AOX activities observed at low residual methanol concentrations.     

Growth characteristics and corrinoid production of Methanosarcina barkeri on methanol-acetate medium

Methanosarcina barkeri strain Fusaro was grown on a mixed substrate medium of methanol and acetate. When 50 mM of acetate was added to the methanol basal medium (250 mM), the rates of methane production, methanol consumption, cell growth and corrinoid production were stimulated 3.2, 2.7, 3.5, and 2.4 times, respectively compared with those in methanol alone. Addition of acetate also has significant influence on corrinoid distribution decreasing the intracellular corrinoid content from 6.8 to 3.0 mg/g dry cell and increasing the extracellular corrinoid concentration from 4.0 to 5.4 mg/l. The carbon balance analysis for methanogenesis and cellular growth with or without acetate addition revealed that about 50% of the utilized acetate carbon might be incorporated in the cellular materials and the remaining might be oxidized to generate the electrons which stimulate the methanol reduction to methane, accelerating the metabolic activities of the methanogenesis from methanol consequently enhancing the rates of methane and corrinoid production, and cell growth.     

表达血管生长抑制素的重组毕赤酵母在诱导阶段混合碳源的流加

为进行高密度发酵并实现外源基因的高表达,在表型为Mut^S的重组毕赤酵母（Pichia pastoris）表达人血管生长抑制素的诱导阶段,采用了甘油甲醇混合补料的培养方式。以溶氧水平作为甘油代谢指针来控制甘油限制性流加既可维持一定菌体生长,又不会发生发酵液中残余甘油及有害代谢产物（乙醇）阻遏蛋白表达。当表达阶段的菌体平均比生长速率控制于0.012h^-1,菌体浓度达150 g/L,血管生长抑制素浓度最高达到108 mg/L,血管生长抑制素的平均比生产速率为0.02 mg/(g·h),菌体关于甘油的表观得率为0.69 g/g,菌体关于甲醇的表观得率为0.93g/g,较没有采用甘油限制性流加时都有所提高。     

初始底物浓度对序批式培养光合细菌产氢动力学影响

实验研究了初始底物浓度对序批式培养光合细菌生长、降解及产氢过程的影响,根据最大比生长速率实验数据拟合得到其关于初始底物浓度影响的关联式,并在建立的修正Monod模型基础上建立了光合细菌比生长速率、基质比消耗速率和比产氢速率关于底物初始浓度影响的数学模型,模型预测值与实验结果在光合细菌生长期和稳定期内得到较好吻合,反映了光合细菌生长、降解和产氢过程中受底物初始浓度限制性和抑制性影响的基本规律。分析发现光合细菌生长、降解基质和产氢过程中最适底物浓度为50 mmol/L,初始底物浓度低于或高于该浓度时,光合细菌生长、降解及产氢过程都受到限制性或抑制性影响,且抑制性影响较限制性影响效果更明显;底物比消耗速率受初始底物浓度影响较小。