The Fed-Batch Production of a Thermophilic 2-Deoxyribose-5-Phosphate Aldolase (DERA) in <Emphasis Type="Italic">Escherichia coli</Emphasis> by Exponential Feeding Strategy Control

2-Deoxyribose-5-phosphate aldolase (DERA) catalyzes a sequential aldol reaction useful in synthetic chemistry. In this work, the effect of a feeding strategy on the production of a thermophilic DERA was investigated in fed-batch cultures of recombinant Escherichia coli BL21 (pET303-DERA008). The predetermined specific growth rate (μ _set) was evaluated at 0.20, 0.15, and 0.10 h⁻¹, respectively. The DERA concentration and volumetric productivity were associated with μ _set. The cells synthesized the enzyme most efficiently at μ _set = 0.15 h⁻¹. The maximum enzyme concentration (5.12 g/L) and total volumetric productivity (0.256 g L⁻¹ h⁻¹) obtained were over 10 and five times higher than that from traditional batch cultures. Furthermore, the acetate concentration remained at a relatively low level, less than 0.4 g/L, under this condition which would not inhibit cell growth and target protein expression. Thus, a specific growth rate control strategy has been successfully applied to induce fed-batch cultures for the maximal production of the thermophilic 2-deoxyribose-5-phosphate aldolase.     

Continuous Production of Oxytetracycline in Fluidized Bed Bioreactor by Immobilized Cells of Streptomyces varsoviensis MTCC-1537: Effect of Dilution and Glucose Loading Rates

Oxytetracycline (OT) production using glutaraldehyde cross-linked calcium alginate immobilized cells of Streptomyces varsoviensis in continuous fluidized bed reactor (FBR) was investigated. Initially, batch experiments were carried in stirred tank reactor (STR) and FBR using calcium alginate immobilized cells. Higher OT production of 0.45 gm/L was achieved by FBR when compared with 0.33 g/L of OT in STR. All subsequent studies were carried out in continuous mode of operation in FBR. During 21 days of operation, effect of glucose concentration and different dilution rates were studied. A maximum of 0.75 g/L OT was achieved in the medium having 10 g/L of glucose concentration. The highest OT concentration of 0.92 g/L and the highest yield of OT with respect to biomass at 0.1713 g/g were obtained at the dilution rate of 0.25 day⁻¹.     

Optimization of Fermentation Conditions for the Biosynthesis of <Emphasis Type="SmallCaps">l</Emphasis>-Threonine by <Emphasis Type="Italic">Escherichia coli</Emphasis>

In this study, the fed-batch fermentation technique was applied to improve the yield of l-threonine produced by Escherichia coli TRFC. Various fermentation substrates and conditions were investigated to identify the optimal carbon source, its concentration and C/N ratio in the production of l-threonine. Sucrose was found to be the optimal initial carbon source and its optimal concentration was determined to be 70 g/L based on the results of fermentations conducted in a 5-L jar fermentor using a series of fed-batch cultures of E. coli TRFC. The effects of glucose concentration and three different feeding methods on the production of l-threonine were also investigated in this work. Our results showed that the production of l-threonine by E. coli was enhanced when glucose concentration varied between 5 and 20 g/L with DO-control pulse fed-batch method. Furthermore, the C/N ratio was a more predominant factor than nitrogen concentration for l-threonine overproduction and the optimal ratio of ammonium sulfate to sucrose (g/g) was 30. Under the optimal conditions, a final l-threonine concentration of 118 g/L was achieved after 38 h with the productivity of 3.1 g/L/h (46% conversion ratio from glucose to threonine).     

Enhanced β-Galactosidase Production from Whey Powder by a Mutant of the Psychrotolerant Yeast <Emphasis Type="Italic">Guehomyces pullulans</Emphasis> 17<Emphasis Type="Italic">–</Emphasis>1 for Hydrolysis of Lactose

In order to isolate β-galactosidase overproducers of the psychrotolerant yeast Guehomyces pullulans 17–1, its cells were mutated by using nitrosoguanidine (NTG). One mutant (NTG-133) with enhanced β-galactosidase production was obtained. The mutant grown in the production medium with 30.0 g/l lactose and 2.0 g/l glucose could produce more β-galactosidase than the same mutant grown in the production medium with only 30.0 g/l lactose while β-galactosidase production by its wild type was sensitive to the presence of glucose in the medium. It was found that 40.0 g/l of the whey powder was the most suitable for β-galactosidase production by the mutant. After optimization of the medium and cultivation conditions, the mutant could produce 29.2 U/ml of total β-galactosidase activity within 132 h at the flask level while the mutant could produce 48.1 U/ml of total β-galactosidase activity within 144 h in 2-l fermentor. Over 77.1% of lactose in the whey powder (5.0% w/v) was hydrolyzed in the presence of the β-galactosidase activity of 280 U/g of lactose within 9 h while over 77.0% of lactose in the whey was hydrolyzed in the presence of β-galactosidase activity of 280 U/g of lactose within 6 h. This was the first time to show that the β-galactosidase produced by the psychrotolerant yeast could be used for hydrolysis of lactose in the whey powder and whey.     

Influence of Osmotic Stress on Fermentative Production of Succinic Acid by <Emphasis Type="Italic">Actinobacillus succinogenes</Emphasis>

This study investigated the influence of osmotic stress on succinic acid production by Actinobacillus succinogenes NJ113. Both cell growth and succinic acid production were inhibited with the increase in osmotic stress of the medium. The use of three different osmoprotectants in the production of succinic acid was studied in order to decrease the inhibitory effects of osmotic stress during fermentation. Results indicated that proline offers optimal osmoprotection in the production of succinic acid by A. succinogenes NJ113. In tests of batch fermentation, the maximum cell concentration was observed to be 5.36 g DCW/L after the addition of 25 mmol/L proline to the fermentation medium. The cell concentration was 24% higher than that noted for the control. A total quantity of 56.2 g/L of succinic acid was produced, with a production rate of 1 g/L per hour, after 56 h of fermentation. The concentration and productivity of succinic acid was observed to be increased by 22.2% and 22%, respectively, as compared with the control. The specific activity levels of key enzymes in the metabolic network was noted to be higher following the addition of proline, particularly in the later stages of fermentation. This method of enhancing succinic acid production by the addition of an osmoprotectant may potentially provide an alternative approach for enhanced production of other organic acids.     

Rhamnolipid Production by <Emphasis Type="Italic">Pseudomonas Aeruginosa</Emphasis> GIM 32 Using Different Substrates Including Molasses Distillery Wastewater

A rhamnolipid production strain newly isolated from oil-contaminated soil was identified as Pseudomonas aeruginosa GIM32 by its morphology and 16S rDNA sequence analysis. The effect of carbon source and carbon to nitrogen (C/N) ratio on rhamnolipids production was investigated. Palm oil was favorable as a carbon source for rhamnolipid production. The maximum biomass and rhamnolipid concentration were 8.24 g/L and 30.4 g/L, respectively, with an optimization medium containing 50 g/L palm oil and 5 g/L sodium nitrate. Molasses distillery wastewater as an unconventional substrate for rhamnolipid production was investigated. It was found that 2.6 g/L of rhamnolipids was produced; this amount was higher than that of past reports using wastewater as a substrate. In addition, 44% of the chemical oxygen demand of wastewater was removed at the same time under the optimization condition. Eleven kinds of different molecular weight rhamnolipid homologues were identified in the rhamnolipids obtained from molasses distillery wastewater by P. aeruginosa GIM32 by LC–MS analysis.     

Effect of Constant Glucose Feeding on the Production of Exopolysaccharides by <Emphasis Type="Italic">Tremella fuciformis</Emphasis> Spores

A fed-batch culture system with constant feeding (glucose 80 g L⁻¹, 0.25 ml min⁻¹) was used to study the influence of glucose on cell dry weight and exopolysaccharides production from submerged Tremella fuciformis spores in a 5-L stirred-tank bioreactor. The results showed that high levels of cell mass (9.80 g L⁻¹) and exopolysaccharides production (3.12 g L⁻¹) in fed-batch fermentation were obtained after 1 h of feeding, where the specific growth rate (μ) and exopolysaccharides yield on substrate consumed (YP/S) were 0.267 d⁻¹ and 0.14 g g⁻¹. Unlike batch fermentation, maximal cell mass and exopolysaccharides production merely reached 7.11 and 2.08 g L⁻¹; the specific growth rate (μ) and exopolysaccharides yield on substrate consumed (YP/S) were 0.194 d⁻¹ and 0.093 g g⁻¹, respectively. It is concluded that the synthesis of exopolysaccharides can be promoted effectively when feeding glucose at a late exponential phase.     

Variable Volume Fed-Batch Fermentation for Nisin Production by <Emphasis Type="Italic">Lactococcus lactis</Emphasis> subsp<Emphasis Type="Italic">. lactis W28</Emphasis>

A feeding technology that was suitable for improving the nisin production by Lactococcus lactis subsp. lactis W28 was established. The effects of initial sucrose concentration (ISC) in the fermentation broth, feeding time, and feeding rate on the fermentation were studied. It was observed that a fed-batch culture (ISC = 10 g l⁻¹) with 100 ml sucrose solution (190 g l⁻¹) being evenly fed (9–10 ml h⁻¹) into the fermenter after 3-h fermentation gave the best performance in terms of biomass and nisin yield. Under these conditions, the total biomass and the total nisin yield were approximately 23% and 51% higher than those in batch fermentation, respectively. When the sucrose concentration was controlled at 5–10 g l⁻¹ in variable volume intermittent fed-batch fermentation (VVIF) with ISC = 10 g l⁻¹, the total biomass and the total nisin yield were 29% and 60% above those in batch fermentation, respectively. The VVIF proved to be effective to eliminate the substrate inhibition by maintaining sucrose at appropriate levels. It is also easy to be scaled up, since various parameters involved in industrial production were taken into account.     

Effects on feeding rate and biomarker responses of marine mussels experimentally exposed to propranolol and acetaminophen

Environmental risk assessments of human pharmaceuticals and other ‘emerging contaminants’ should integrate both population-relevant endpoints and biomarkers of potential modes of action in a range of species. Adult Mytilus galloprovincialis were exposed to the beta-adrenergic receptor blocker propranolol or to the anti-inflammatory drug acetaminophen (paracetamol), both commonly used therapeutic drugs present in aquatic ecosystems. Mussels were exposed under semi-static conditions for 10 days to either acetaminophen (CAS number 103-90-2; mean measured concentrations 23 and 403 μg/L) or propranolol hydrochloride (CAS number 318-98-9; mean measured propranolol concentrations 11 and 147 μg/L) at 15 ± 1 °C sea water. Feeding rate was assessed as an indicator of general toxicity. For propranolol, the 10-day no-observed effect concentration (^{feeding rate}NOEC) and lowest observed effect concentration (^{feeding rate}LOEC) were 11 and 147 μg/L, respectively. For acetaminophen, feeding rate was increased at both 23 and 403 μg/L, suggesting a 10-day ^{feeding rate}NOEC of 403 μg/L. Primarily, phase I carboxylesterase (CbE), phase II glutathione S-transferase (GST) and the anti-oxidant catalase activities were evaluated in digestive gland. Gill GST and acetylcholinesterase (AChE) activities were also measured. Lipid peroxidation (LPO) levels were measured in both tissues to assess oxidative stress. Some enzymatic activities in liver were also reduced after propranolol exposure whilst acetaminophen enhanced them (CbE p < 0.05). Acetaminophen exposure significantly increased hepatic LPO levels and inhibited AChE activity in gill (10-day NOEC and LOEC of 23 and 403 μg/L, respectively), whereas propranolol (11 μg/L) enhanced gill GST.     

Constitutive Expression of <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis> Lipase LIP2 in <Emphasis Type="Italic">Pichia pastoris</Emphasis> Using GAP as Promoter

A gene encoding Yarrowia lipolytica lipase LIP2 (YlLIP2) was cloned into a constitutive expression vector pGAPZαA and electrotransformed into the Pichia pastoris X-33 strain. The high-yield clones obtained by high copy and enzyme activity screening were chosen as the host strains for shaking flask and fermentor culture. The results showed that glucose was the optimum carbon source for YlLIP2 production, and the maximum hydrolytic activity of recombinant YlLIP2 reached 1,315 U/ml under the flask culture at 28 °C, pH 7.0, for 48 h. The fed-batch fermentation was carried out in 3- and 10-l bioreactors by continuously feeding glucose into the growing medium for achieving high cell density and YlLIP2 yields. The maximum hydrolytic activity of YlLIP2 and cell density obtained in the 3-l bioreactor were 10,300 U/ml and 116 g dry cell weight (DCW)/l, respectively. The peak hydrolytic activity of YlLIP2 and cell density were further improved in the 10-l fermentor where the values respectively attained were 13,500 U/ml and 120 g DCW/l. The total protein concentration in the supernatant reached 3.3 g/l and the cell viability remained approximately 99% after 80 h of culture. Furthermore, the recombinant YlLIP2 produced in P. pastoris pGAP and pAOX1 systems have similar content of sugar (about 12%) and biochemical characteristics. The above results suggest that the GAP promoter-derived expression system of P. pastoris is effective for the expression of YlLIP2 by high cell density culture and is probably an alternative to the conventional AOX1 promoter expression system in large-scale production of industrial lipases.     

Heterotrophic Culture of <Emphasis Type="Italic">Chlorella protothecoides</Emphasis> in Various Nitrogen Sources for Lipid Production

The influences of urea, yeast extract, and nitrate as the nitrogen source on heterotrophic growth of four strains of Chlorella protothecoides were investigated in 9-day feed-batch cultures. Biomass dry weight concentration (DWC) and lipid yield (LY) of the four strains in all media were compared. The highest LY in 9 days was 654 mg/L/day by UTEX 255 in 2.4 g/L KNO₃ medium with a biomass DWC of 11.7 g/L and lipid content of 50.5%. Using green autotrophic seeds instead of yellow heterotrophic seeds improved the biomass DWC (13.1 vs. 11.7 g/L), LY (850 vs. 654 mg/L/day), and lipid to glucose consumption ratio (0.607 vs. 0.162). Moreover, 17.0 g/L DWC and 489 mg/L/day LY were obtained from the sequentially mixed-nitrogen medium, and the lipid to glucose consumption ratio was improved to 0.197 from 0.162 in 2.4 g/L nitrate medium and from 0.108 in 4.2 g/L yeast extract medium in the first batch.     

Kinetic and Stoichiometric Parameters in the Production of Carotenoids by <Emphasis Type="Italic">Sporidiobolus salmonicolor</Emphasis> (CBS 2636) in Synthetic and Agroindustrial Media

With the objective of determining the kinetic behavior (growth, substrate, pH, and carotenoid production) and obtain the stoichiometric parameters of the fermentative process by Sporidiobolus salmonicolor in synthetic and agroindustrial media, fermentations were carried out in shaken flasks at 25°C, 180 rpm, and initial pH of 4.0 for 120 h in the dark, sampling every 6 h. The maximum concentrations of total carotenoids in synthetic (913 μg/L) and agroindustrial (502 μg/L) media were attained approximately 100 h after the start of the fermentative process. Carotenoid bioproduction is associated with cell growth and the ratio between carotenoid production and cell growth (Y _P/X) is 176 and 163 μg/g in the synthetic and agroindustrial media, respectively. The pH of the agroindustrial fermentation medium varied from 4.2 to 8.5 during the fermentation. The specific growth rate (μ _X) for S. salmonicolor in synthetic and agroindustrial media was 0.07 and 0.04 h⁻¹, respectively. The synthetic medium allowed for greater productivity, obtaining maximum cell productivity (P _x) of 0.08 g L⁻¹ h⁻¹ and maximum total carotenoid productivity (P _car) of 14.2 μg L⁻¹ h⁻¹. Knowledge of the kinetics of a fermentative process is of extreme importance when transposing a laboratory experiment to an industrial scale, as well as making a quantitative comparison between different culture conditions.     

An Effective and Simplified Fed-Batch Strategy for Improved 2,3-Butanediol Production by <Emphasis Type="BoldItalic">Klebsiella oxytoca</Emphasis>

Substrate concentration in 2,3-butanediol (2,3-BD) fermentation could not be controlled well in traditional feeding strategies, such as constant, impulse, and exponential feeding strategies. In the present study, fermentative 2,3-BD production by Klebsiella oxytoca was investigated under different batch and fed-batch strategies. The glucose-feedback fed-batch strategy was proved to be not effective for economical 2,3-BD production for the inability of timely feeding, leading that the bacteria reused 2,3-BD as carbon source for cell growth. Based on the phenomena that the byproducing acids caused the pH declining and the requirement of maintaining the pH at a proper level for both cell growth and 2,3-BD accumulation, an improved strategy of pH-stat fed-batch culture with glucose and sodium hydrate fed at the same time was established. Thus, the residual glucose concentration could be controlled through the adjustment of pH automatically. At last, efficient 2,3-BD production was fulfilled under this fed-batch strategy, and the highest 2,3-BD concentration, productivity, and yield were 127.9 g/l, 1.78 g/(l•h), and 0.48 g/g (2,3-BD/glucose), respectively, compared to 98.5 g/l, 1.37 g/(l•h), and 0.43 g/g obtained in glucose-feedback fed-batch strategy. This feeding strategy was simple and easy to operate and could be feasible for industrial 2,3-BD production in the future.     

Continuous Ethanol Production from Cassava Through Simultaneous Saccharification and Fermentation by Self-Flocculating Yeast Saccharomyces Cerevisiae CHFY0321

In this study, a fermentor consisting of four linked stirred towers that can be used for simultaneous saccharification and fermentation (SSF) and for the accumulation of cell mass was applied to the continuous production of ethanol using cassava as the starchy material. For the continuous process with SSF, the pretreated cassava liquor and saccharification enzyme at total sugar concentrations of 175 g/L and 195 g/L were continuously fed to the fermentor with dilution rates of 0.014, 0.021, 0.031, 0.042, and 0.05 h⁻¹. Considering the maximum saccharification time, the highest volumetric productivity and ethanol yield were observed at a dilution rate of 0.042 h⁻¹. At dilution rates in the range of 0.014 h⁻¹ to 0.042 h⁻¹, high production rates were observed, and the yeast in the first to fourth fermentor showed long-term stability for 2 months with good performance. Under the optimal culture conditions with a feed sugar concentration of 195 g/L and dilution rate of 0.042 h⁻¹, the ethanol volumetric productivity and ethanol yield were 3.58 g/L∙h and 86.2%, respectively. The cell concentrations in the first to fourth stirred tower fermentors were 74.3, 71.5, 71.2, and 70.1 g dry cell/L, respectively. The self-flocculating yeast, Saccharomyces cerevisiae CHFY0321, developed by our group showed excellent fermentation results under continuous ethanol production.     

An Enhanced Process for the Production of a Highly Purified Extracellular Lipase in the Non-conventional Yeast <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis>

Yarrowia lipolytica LgX64.81 is a non-genetically modified mutant that was previously identified as a promising microorganism for extracellular lipase production. In this work, the development of a fed-batch process for the production of this enzyme in this strain was described. A lipolytic activity of 2,145 U/mL was obtained after 32 h of batch culture in a defined medium supplemented with 10 g/L of tryptone, an enhancer of lipase expression. To maximize the volumetric productivity, two different fed-batch strategies had been investigated. In comparison to batch process, the intermittent fed-batch strategy had not improved the volumetric lipase productivity. In contrast, the stepwise feeding strategy combined with uncoupled cell growth and lipase production phases resulted in a 2-fold increase in the volumetric lipase productivity, namely, the lipase activity reached 10,000 U/mL after 80 h of culture. Furthermore, this lipase was purified to homogeneity by anion exchange chromatography on MonoQ resin followed by gel filtration on Sephacryl S-100. This process resulted in an overall yield of 72% and a 3.5-fold increase of the specific lipase activity. The developed process offers a great potential for an economic production of Lip2 at large scale in Y. lipolytica LgX64.81.     

Production of Butyric Acid from Glucose and Xylose with Immobilized Cells of <Emphasis Type="Italic">Clostridium tyrobutyricum</Emphasis> in a Fibrous-bed Bioreactor

Butyric acid has many applications in chemical, food, and pharmaceutical industries. In the present study, Clostridium tyrobutyricum ATCC 25755 was immobilized in a fibrous-bed bioreactor to evaluate the performance of butyrate production from glucose and xylose. The results showed that the final concentration and yield of butyric acid were 13.70 and 0.46 g g⁻¹, respectively, in batch fermentation when 30 g L⁻¹ glucose was introduced into the bioreactor. Furthermore, high concentration 10.10 g L⁻¹ and yield 0.40 g g⁻¹ of butyric acid were obtained with 25 g L⁻¹ xylose as the carbon source. The immobilized cells of C. tyrobutyricum ensured similar productivity and yield from repeated batch fermentation. In the fed-batch fermentation, the final concentration of butyric acid was further improved to 24.88 g L⁻¹ with one suitable glucose feeding in the fibrous-bed bioreactor. C. tyrobutyricum immobilized in the fibrous-bed bioreactor would provide an economically viable fermentation process to convert the reducing sugars derived from plant biomass into the final bulk chemical (butyric acid).     

Production of lactic acid from cheese whey by batch and repeated batch cultures of Lactobacillus sp. RKY2

The fermentative production of lactic acid from cheese whey and corn steep liquor (CSL) as cheap raw materials was investigated by using Lactobacillus sp. RKY2 in order to develop a cost-effective fermentation medium. Lactic acid yields based on consumed lactose were obtained at more than 0.98 g/g from the medium containing whey lactose. Lactic acid productivities and yields obtained from whey lactose medium were slightly higher than those obtained from pure lactose medium. The lactic acid productivity gradually decreased with increase in substrate concentration owing to substrate and product inhibitions. The fermentation efficiencies were improved by the addition of more CSL to the medium. Moreover, through the cell-recycle repeated batch fermentation, lactic acid productivity was maximized to 6.34 g/L/h, which was 6.2 times higher than that of the batch fermentation.     

Application of a pH Feedback-Controlled Substrate Feeding Method in Lactic Acid Production

Substrate concentration in lactic acid fermentation broth could not be controlled well by traditional feeding methods, including constant, intermittent, and exponential feeding methods, in fed-batch experiments. A simple feedback feeding method based on pH was proposed to control pH and substrate concentration synchronously to enhance lactic acid production in fed-batch culture. As the linear relationship between the consumption amounts of alkali and that of substrate was concluded during lactic acid fermentation, the alkali and substrate in the feeding broth were mixed together proportionally. Thus, the concentration of substrate could be controlled through the adjustment of pH automatically. In the fed-batch lactic acid fermentation with Lactobacillus lactis-11 by this method, the residual glucose concentration in fermentation broth was controlled between 4.1 and 4.9 g L⁻¹, and the highest concentration of lactic acid, maximum cell dry weight, volumetric productivity of lactic acid, and yield were 96.3 g L⁻¹, 4.7 g L⁻¹, 1.9 g L⁻¹ h⁻¹, and 0.99 g lactic acid per gram of glucose, respectively, compared to 82.7 g L⁻¹, 3.31 g L⁻¹, 1.7 g L⁻¹ h⁻¹, and 0.92 g lactic acid per gram of glucose in batch culture. This feeding method was simple and easily operated and could be feasible for industrial lactic acid production in the future.     

Enhancement of Human γ-Interferon Production in Recombinant <Emphasis Type="Italic">E. coli</Emphasis> Using Batch Cultivation

Development of inexpensive and simple culture media and appropriate induction conditions are always favorable for industry. In this research, chemical composition and stoichiometric data for γ-interferon production and recombinant Escherichia coli growth were used in order to achieve a simple medium and favorable induction conditions. To achieve this goal, the effects of medium composition and induction conditions on the production of γ-interferon were investigated in batch culture of E. coli BL21 (DE3) [pET3a-ifnγ]. These conditions were considered as suitable conditions for the production of γ-interferon: 2.5× M9 medium, supplemented with a mixture of amino acids (milligram per liter), including glutamic acid 215, aspartic acid 250, lysine 160, and phenylalanine 90, and induction at late-log phase (OD₆₀₀ = 4.5). Under these conditions, dry cell weight of 6 ± 0.2 g/l and γ-interferon concentration of 2.15 ± 0.1 g/l were obtained. Later, without changing the concentration ratio of amino acids and glucose, the effect of increase in the primary glucose concentration on productivity of γ-interferon was investigated. It was found that 25 g/l glucose will result in maximum attainable biomass and recombinant human γ-interferon. At improved conditions, a dry cell weight of 14 ± 0.2 g/l, concentration and overall productivity of γ-interferon 4.2 ± 0.1 g/l and 420 ± 10 mg/l h, respectively, were obtained.     

Water Hyacinth as Carbon Source for the Production of Cellulase by <Emphasis Type="Italic">Trichoderma reesei</Emphasis>

Water hyacinth (Eichhornia crassipes), an aquatic weed common to the subtropic/tropical regions, was utilized as an inexpensive lignocellulosic substrate for production of cellulase by Trichoderma reesei. The effects of process parameters like substrate pretreatment, substrate concentration, initial medium pH, mode of inoculation, and incubation temperature on cellulase production were investigated. Under optimal conditions, a maximal cellulase activity of 0.22 ± 0.04 IU/ml (approximately 73.3 IU/g cellulose) was recorded at the end of 15-day incubation period. Specific activity of the enzyme was 6.25 IU/mg protein. Hydrolysis of 1% substrate (water hyacinth) using crude enzyme dosage of 1.2 IU/g water hyacinth showed 28.7% saccharification in 1 h. The observations in present study indicate that saccharification of cellulose from water hyacinth was significantly higher by laboratory-produced cellulase than the commercial blend.