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Upcycle of co-products from corn–ethanol plant into protein-rich animal feed with balanced key amino acids via solid-state fermentation is a promising approach to economically support both biofuel and animal feed industries. However, there are multiple types of solid-state fermentation microorganisms and growth conditions that have not been tested. In this study, Mucor indicus and Rhizopus oryzae were used to ferment corn-based wet distiller’s grains with solubles (WDGS). The effects of fermentation conditions (temperature, agitation, and moisture) and supplementations (extraneous carbon and nitrogen sources) were evaluated on protein production and amino acids profiles before and after fermentation. The study established best fermentation conditions (23 °C, static incubation for 4 days at 70% initial moisture content) to improve protein content for both R. oryzae and M. indicus. Moreover, urea supplied to R. oryzae and M. indicus improved protein concentration by 35 and 38%, and total amino acids content by 28 and 18%, respectively. The amount of 693.1 and 451.8 mg of additional total amino acids including 262.8 and 227.7 mg of key amino acids (lysine, methionine, tryptophan, and arginine) was synthesized by R. oryzae and M. indicus, respectively, per supply of 536 mg urea in 25 g of WDGS. This study demonstrated the feasibility of urea as a low-cost nitrogen source for amino acid biosynthesis in fungal fermentation of WDGS, which could contribute to the increasing demand for high-value monogastric animal feed.

The establishment of an efficient and feasible biorefinery model depends on, among other factors, particularly the selection of the most appropriate microorganism. Mucor circinelloides is a dimorphic fungus species able to produce a wide variety of hydrolytic enzymes, lipids prone to biodiesel production, carotenoids, ethanol, and biomass with significant nutritional value. M. circinelloides also has been selected as a model species for genetic modification by being the first filamentous oleaginous species to have its genome fully characterized, as well as being a species characterized as a potential bioremediation agent. Considering the potential of replacing several nonrenewable feedstocks is widely dependent on fossil fuels, the exploitation of microbial processes and products is a desirable solution for promoting a green and sustainable future. Here, we introduce and thoroughly describe the recent and critical applications of this remarkable fungus within the context of developing a fungal-based biorefinery.

Upcycle of co-products from corn-ethanol plant into protein-rich animal feed with balanced key amino acids via solid-state fermentation is a promising approach to economically support both biofuel and animal feed industries. However, there are multiple types of solid-state fermentation microorganisms and growth conditions that have not been tested. In this study, Mucor indicus and Rhizopus oryzae were used to ferment corn-based wet distiller's grains with solubles (WDGS). The effects of fermentation conditions (temperature, agitation, and moisture) and supplementations (extraneous carbon and nitrogen sources) were evaluated on protein production and amino acids profiles before and after fermentation. The study established best fermentation conditions (23 °C, static incubation for 4 days at 70% initial moisture content) to improve protein content for both R. oryzae and M. indicus. Moreover, urea supplied to R. oryzae and M. indicus improved protein concentration by 35 and 38%, and total amino acids content by 28 and 18%, respectively. The amount of 693.1 and 451.8 mg of additional total amino acids including 262.8 and 227.7 mg of key amino acids (lysine, methionine, tryptophan, and arginine) was synthesized by R. oryzae and M. indicus, respectively, per supply of 536 mg urea in 25 g of WDGS. This study demonstrated the feasibility of urea as a low-cost nitrogen source for amino acid biosynthesis in fungal fermentation of WDGS, which could contribute to the increasing demand for high-value monogastric animal feed.

With the increase in intensive crop and livestock production, excess application of P as fertilizer and manure contributes to the build-up of soil P levels causing eutrophication. A novel biofilm-based technology was developed to recover and reposition the nutrients in manure, producing biofilm fertilizer and the treated water with better nutrient composition. Anaerobically digested and pretreated manure was used as a medium to grow the surface-attached composite biofilm, which constitutes the selected polyphosphate accumulating fungi and nitrogen accumulating fresh water microalgae for efficient recovery of nutrients on a matrix for better biomass harvesting. Under the tested conditions in lab-scale with the pretreated digested manure, the removal efficiency of the nutrients by attached mycoalgae biofilm was 76.74% P and 76.40% N with COD removal of 65.75%. To increase the nutrient content of the biomass and for enhancing the cell growth the wastewater generated in corn ethanol process (thin stillage) was added as an external nutrient at different ratios in the digested manure. The cell growth, nutrient removal efficiency, lipid content of the biomass, COD removal and reducing sugar content at different medium conditions were evaluated. The nutrient-rich solid biofilm can be harvested by scraping off the biofilm from the matrix and the nutrient lean liquid can be discharged or further used for agriculture. The microbial biofilm assimilates the organic and inorganic components in manure and converts them into cellular constituents together with N-P-K resulting in deposition of manure nutrients in biofilm, which can be directly used as a bio-fertilizer.

Phytate, the principal storage form of phosphorus in corn, is found to remain as a significant portion of phosphorus in the corn-ethanol coproducts streams. This poses concerns over poor digestion of these coproducts by monogastric animals and subsequent environmental issues on phosphorus. An ion-exchange-based process was developed to extract the phytate from thin stillage, which was selected as the influent based on the inositol phosphate distribution conducted on different corn-ethanol coproducts. Commercial industrial resins (IRA-93, IRA-68, IRA-900, IRA-400, and IRA-402) were characterized and screened for the phytate adsorption, specificity and capacity. Different types of eluents (NaOH, NaCl, NaHCO3, HCl, and NH4OH) were tested to evaluate the desorption capacity in all the six resins. Phytate-P isotherms and kinetics of the adsorption process, breakthrough profile on IRA-900 column and phytate elution curves were presented. This process yields a phytate-rich solution (11 g L–1), which is 25-fold c...

Grain-to-ethanol production has increased steadily in the United States in the past few decades, which resulted in remarkable records in the availability of co-products. Dry-grind is the most common method of ethanol production worldwide, which concentrates the corn and yeast nutrients in the downstream operations. The ethanol co-products have traditionally been a commodity for livestock feed as they contain desirable nutrients, mostly sold as distiller’s grains. The liquid fraction produced after the centrifugation of the bottoms of the ethanol rectifying and distilling operations is named thin stillage, produced at volumes several times greater than those of ethanol. A portion of thin stillage is normally recycled as backset water, while the remaining goes through a series of evaporations. Evaporating a large amount of water from thin stillage is an energy-consuming process and recycling the thin stillage may lead to the accumulation of nutrients in co-products in distiller’s grains. There are several other industrial processes to utilize thin stillage, such as oil extraction, anaerobic digestion, and secondary fermentation. Recently, promising results have been reported on the production of important commodity chemicals, extracting high-value products, and energy production from thin stillage. This review provides an overview on the new processes and products via valorization of thin stillage by innovative technologies that are being currently developed. The new applications of thin stillage discussed in this review could open new opportunities for the ethanol plants and ethanol researchers by increasing the revenue and simultaneously reducing negative environmental impacts of ethanol production.

Microalgae harvesting is a difficult and costly unit operation, hampering commercial microalgae based processes. Various innovative approaches have been under research investigations. Algae harvesting using microalgae/fungi co-pelletization where microalgae cells are attracted to filamentous fungus and form co-pellets during their co-culture has been proved to be an innovative approach that might be both cost effective and sustainable. Yet, the mechanism behind the co-pelletization based algae harvesting is still not known. Understanding its mechanism will significantly facilitate future developments to decrease the processing cost for generating biofuel and other microalgae based bio-products. Considering that the ionic conditions greatly affect the flocculation performance of microalgae cells, studies were conducted to compare the co-pelletization performance at different pH values and ionic strengths in order to evaluate the surface charge changes at the different conditions tested. Zeta-potential measurements indicated that (1) both microalgae and fungi have low negative zeta-potentials regardless of the pH of the bulk solution ( 0.1 g/L) the surface charge of fungal and microalgae cells were less negative (>−5 mV for fungal hyphae and >−12 mV for microalgae) at higher concentrations of magnesium (0.5 g/L), which might have facilitated the attraction between them.

The exchange of nutrients among different species is one of the most complex, intriguing, and important factors that favored the development of certain microorganisms in evolutionary systems. As a direct result of this, microorganisms in natural system often co-exist with many others in an organized manner. From an engineering approach, the benefits of having multiple microorganisms in a bioprocess may be beneficial to a number of reasons, including favoring the preferred metabolic pathways of one organism, simultaneously by promoting other additional effects by another. Among the many examples of microbial communities or consortia, one of the most studied from a biological point of view are known as lichens—a combination of fungi and algae and/or cyanobacteria. Adding to the fact that over one fifth of all fungal species today known to be in its lichenized form, it is crucial to understand the hidden benefits that such combination can offer to biosystems engineers. Fungal-algal symbiotic relationships often offer significant and efficient exchange of gases, promoting a healthy growth, and can be directly applied towards the solution of a wide range of issues faced today by biorefineries. This chapter summarizes some of the applications of this novel, yet promising, concept, including algal harvesting, lipid accumulation, and bioremediation of wastewater, presenting also a brief history and perspectives on the concept.

The present study was aimed to enhance the production of compactin by Aspergillus terreus MTCC 279 in mixed substrate solid state fermentation (SSF) using various solid substrates. Twenty solid substrates including agricultural residues and other solid substrates were tested for the compactin and lovastatin production by A. terreus. Among the twenty substrates tested, the three substrates which gave maximum compactin production was taken for further optimization in mixed substrate solid state fermentation in various combinations using response surface methodology. Green peas, millet and ragi were found to be suitable substrates which produced maximum compactin production in SSF. The combinations of the substrates with 1.5 g of green peas, 1.5 g of millet and 1.5 g of ragi gave maximum production of 389.34 mg/gds compactin and 1,467.12 mg/gds lovastatin. Response surface methodology was used to determine the optimal combination of each substrate. To the best of our knowledge this is the first report on enhancing compactin production in mixed substrate solid state fermentation.

Tannin acyl hydrolase (tannase) production by Lactobacillus plantarum MTCC1407 was studied in submerged and solid-state fermentation process. Sequential optimization strategy using Plackett–Burman screening and response surface methodology was adopted to optimize the submerged fermentation process. Eight medium components were evaluated initially by Plackett–Burman two level factorial designs to identify the most significant parameters that affect the tannase production. The significant variables affecting tannase production were found to be tannic acid, glucose and MnSO4·7H2O. These factors were further optimized by response surface methodology. Maximum tannase activity of 9.13 U ml−1 was observed at 30 h using the following medium composition (g l−1): tannic acid, 13.16; glucose, 1.5; NH4Cl, 1.0; CaCl2·2H2O, 1.0; K2HPO4, 0.5; KH2PO4, 0.5; MgSO4·7H2O, 0.5 and MnSO4·7H2O, 0.03. Among the various carbon sources examined for tannase production by L. plantarum, glucose and tannic acid combination was found to be decisive for enhancing tannase yield. Solid state fermentation was conducted using various solid substrates and agricultural residues. Maximum tannase activity of 5.319 U gds−1 was obtained using coffee husk as substrate.

Utilizing agricultural wastes for the production of industrially valuable enzymes like lipases in solid state fermentation holds a promising alternative for conventional processes due to the various obvious advantages, especially the cost-effectiveness of the process and sustainability. In this present work, the feasibility of exploiting various agricultural residues for lipase production was evaluated and optimization of the important parameters was done using statistical methods. Candida rugosa NCIM 3462 was used for the production of lipase in solid state fermentation. Agro industrial wastes such as sesame oil cake, groundnut oil cake and coconut oil cake were used for the solid state fermentation. The Energy dispersion spectrum of the solid substrates was used to study the elemental composition of oil cakes. The response surface methodology was employed to optimize the lipase production and to study the effect of temperature and substrate to moisture ratio. The maximum lipase activity of 22.40 U/g substrate was obtained using sesame oil cake which was 1.8 times the maximum activity obtained during the initial screening of variables by ‘one-factor-at-time’ approach. The optimized temperature and substrate to moisture ratio were found to be 32.3 °C and 1:3.23 g/ml respectively. A predictive model for the combined effects of the independent variables using response surface methodology and artificial neural network was proved to be excellent empirical model for lipase production by C. rugosa in solid state fermentation and aid in improving lipase fermentation utilizing agricultural residues as valuable substrates.

Non-edible oils represent one of the most viable alternative feed stocks for the production of large volumes of biodiesel at cheaper cost in tropical countries. The objective of the present study is to investigate the ability of the immobilized whole cells of Rhizopus oryzae MTCC 262 to catalyze the biodiesel production from karanja oil in n-hexane system. Response surface methodology was employed to evaluate the effects of synthesis parameters, such as molar ratio of oil to alcohol, reaction temperature and reaction time on percentage biodiesel (methyl esters) yield. Transesterification was performed in shake flasks containing immobilized cells in the reaction mixture with 10% oil weight of n-hexane. The quadratic effects of molar ratio of oil to alcohol and reaction time proved to be the significant at 1% and 5% levels, respectively. The optimum synthesis conditions were found to be: molar ratio of oil to alcohol 1:2.73, reaction temperature 41.39°C and reaction time 73.97 h. Biodiesel yield (methyl ester) was 75.98 (wt.%) under the optimal conditions and the subsequent verification experiments with biodiesel yield of 78.0 (wt.%) confirmed the validity of the proposed model.

The ability of immobilised whole cells of R. oryzae cells to catalyse the alcoholysis of jatropha oil with methanol in n‐hexane system was investigated. Response surface methodology using central composite design was used to study the effects of important parameters: reaction time, reaction temperature, catalyst concentration, molar ratio of alcohol to oil and water content in five levels on percentage yield of biodiesel. The linear effects of reaction time and catalyst concentration and the quadratic effects of catalyst concentration and molar ratio of alcohol to oil were found to be the significant parameters. The optimum conditions for biodiesel production were found to be: reaction time, 77.25 h; reaction temperature, 40.18°C; catalyst concentration, 3.70 w/v; molar ratio of alcohol to oil, 1:2.88 and water content, 11.20% (w/w of oil). The predicted yield of biodiesel was 79.87% (w/w) and the experimental yield at the optimised condition was 80.5% (w/w). This confirmed the validity of the proposed model.

This study demonstrates the feasibility of large-scale production of murine polyomavirus VP1 protein in recombinant Escherichia coli as pentamers which are able to subsequently self-assemble in vitro into virus-like particles (VLPs). High-cell-density pH-stat fed-batch cultivation was employed to produce glutathione-S-transferase (GST)-VP1 fusion protein in soluble form. The expression of recombinant VP1 was induced with IPTG at different cell optical densities (OD at 600 nm of 20, 60 or 100). GST-VP1 production was highest when the culture was induced at a cell density of OD 60, with volumetric yield reaching 4.38 g L −1 in 31 h, which we believe is the highest volumetric productivity for viral capsid protein reported to date. The induction cell density is shown to have a significant effect on the overall volumetric yield of recombinant VP1 and on final cell density, but not on VLP quality. VP1 yield was enhanced 15-fold by scaling-up from shake flask to pH-stat fed-batch cultivation in a bioreactor. Although numerous studies have expressed structural viral protein in E. coli , we believe this is the first report of translation to bioreactors yielding gram-per-litre levels. This VLP production technology overcomes major drawbacks associated with eukaryotic cell-based vaccine production technologies, and propounds the scope for large-scale commercially viable E. coli based VLP production by significantly reducing vaccine production time and cost.

Lovastatin (HMG-CoA reductase inhibitors), is an important anticholesterolemic drug which inhibits the conversion of HMG-CoA to mevalonate in the biosynthesis of cholesterol. Plackett–Burman statistical screening of 12 media components and subsequent optimization of significant parameters by response surface methodology for the biotechnological production of lovastatin by Monascus purpureus MTCC 369 was studied. In this study, the statistical analysis of Plackett–Burman experimental results showed that the medium components glucose, peptone, MnSO 4 ·H 2 O, NaCl and NH 4 Cl as the significant components influencing the lovastatin production. The most significant medium components, glucose, peptone and MnSO 4 ·H 2 O which have confidence level of more than 95% were further optimized using a full factorial central composite design of the response surface methodology. Maximum lovastatin production of 97.5 mg l −1 was obtained after 14 days of fermentation period in the optimized medium containing, glucose, 52.61 g l −1 peptone, 16.65 g l −1 ; NH 4 Cl, 1 g l −1 ; KH 2 PO 4 , 1 g l −1 ; yeast extract, 3 g l −1 ; K 2 HPO 4 , 1 g l −1 ; KNO 3 , 0.5 g l −1 ; MgSO 4 ·7H 2 O, 0.2 g l −1 ; MnSO 4 ·H 2 O, 0.418 g l −1 ; NaCl, 0.5 g l −1 ; CaCl 2 ·2H 2 O, 0.1 g l −1 and FeSO 4 ·7H 2 O, 0.001 g l −1 at 30 °C and 120 rpm. The production of lovastatin by M. purpureus MTCC 369 in the optimized medium was found to be four times higher than the basal medium in the submerged fermentation. The statistical experimental design serves as an efficient tool for screening large number of variables with minimum number of experiments and optimizing the significant variables for enhancing the production of lovastatin.

Biodiesel, chemically defined as monoalkyl esters of long chain fatty acids, are derived from renewable feed stocks like vegetable oils and animal fats. It is produced by both batch and continuous transesterification processes in which, oil or fat is reacted with a monohydric alcohol in the presence of a catalyst. The conventional method of producing biodiesel involves acid and base catalysts to form fatty acid alkyl esters. Downstream processing costs and environmental problems associated with biodiesel production and byproducts recovery have led to the search for alternative production methods and alternative substrates. Enzymatic reactions involving lipases can be an excellent alternative to produce biodiesel through a process commonly referred to as alcoholysis, a form of transesterification reaction or through an interesterification reaction. In order to increase the cost effectiveness of the process, the enzymes are immobilized using a suitable matrix. The use of immobilized lipases and whole cells may lower the overall cost, while presenting less downstream processing problems. Main focus of this paper is to discuss the important parameters that affect the biodiesel yield, various immobilization techniques employed, mechanisms and kinetics of transesterification reaction and the recent advances in continuous transesterification processes.

The Plackett–Burman experimental design was used to evaluate the medium components for lipase production by Rhizopus arrhizus in submerged batch fermentation. Twelve medium components with three dummy variables were studied in this experimental design. The most significant variables affecting lipase production were found to be olive oil, peptone, KH 2 PO 4 , CaCl 2 ·2H 2 O and MgSO 4 ·7H 2 O. Maximum lipase activity (3.98 U mL −1 ) and maximum cell mass concentration (5.62 g L −1 ) were obtained using the optimised medium. Unstructured kinetic models were analysed to simulate the experimental values of cell growth, lipase activity and glucose concentration. The logistic model for cell growth, the Luedeking–Piret model for lipase production and a modified Luedeking–Piret model for substrate utilisation were found to accurately predict the fermentation kinetics. The estimated values of the kinetic model parameters, α and β , for lipase production indicate that the lipase production by R. arrhizus is growth-associated.

Lipases are one of the most important industrial biocatalyst which catalyzes the hydrolysis of lipids. It can also reverse the reaction at minimum water activity. Because of this pliable nature, it is widely exploited to catalyze the diverse bioconversion reactions, such as hydrolysis, esterification, interesterification, alcoholysis, acidolysis and aminolysis. The property to synthesize the esters from the fatty acids and glycerol promotes its use in various ester synthesis. The esters synthesized by lipase finds applications in numerous fields such as biodiesel production, resolution of the recemic drugs, fat and lipid modification, flavour synthesis, synthesis of enantiopure pharmaceuticals and nutraceuticals. It plays a crucial role in the food processing industries since the process is unaffected by the unwanted side products. Lipase modifications such as the surfactant coating, molecular imprinting to suit for the non-aqueous ester synthesis have also been reported. This review deals with lipase catalyzed ester synthesis, esterification strategies, optimum conditions and their applications in food processing industries.Lipases são catalizadores industriais dos mais importantes, os quais catalizam a hidrólise de lipídeos. Também podem reverter a reação a um mínimo de atividade de água. Devido sua natureza flexível, é amplamente explorada para catalizar uma diversidade de reações de bioconversão como hidrólise, esterificação, interesterificação, alcoólise, acidólise e aminólise. A propriedade de síntese de esteres a partir de ácidos graxos e glicerol promoveu seu uso em várias sínteses de esteres. Os esteres sintetizados por lipases encontram aplicação em numerosos campos como a produção de biodiesel, resolução de drogas racêmicas, modificação de gorduras e lipídios, sintese de aromas, síntese de produtos farmacêuticos enantiopuro e nutracêuticos. As lipases possuem um papel crucial nas indústrias de processamento de alimentos, pois os processos não são afetados por subprodutos indesejáveis. Modificações nas lipases como revestimento tensoativo, impressão molecular, para permitir a síntese de esteres não aquosos também são reportados. Esta revisão trata da síntese de éster catalizada por lipase, estratégia de esterificação, condições ótimas e suas aplicações em indústrias de processamento de alimento.

Lactobacillus plantarumMTCC 1407 represents a valuable source of an economically attractive stable long-life tannase with potential for application in various industries. The effect of fermentation parameters such as pH, temperature and agitation speed on the growth of biomass and production of tannase using liquid medium were determined at the end of fermentation period. The optimum values of pH, reaction temperature and agitation speed for tannase activity were 6.0, 30 °C and 125 rpm respectively. The maximum tannase activity was found to be 9.29 U/mL.

Xylanases are hydrolytic enzymes which randomly cleave the β-1, 4 backbone of the complex plant cell wall polysaccharide xylan. Diverse forms of these enzymes exist, displaying varying folds, mechanisms of action, substrate specificities, hydrolytic activities, and physicochemical characteristics. This article focuses on the fermentative production of xylanase from Arthrobacter sp. and the factors affecting the production. The batch-submerged fermentation was carried out in a 250-ml Erlenmeyer flask. The inoculum size of 5% v/v, initial pH of 7.0, and shaking speed of 150 rpm at 32 °C were maintained for the optimization of medium components. The cell growth, xylanase activity, cellulase activity, protein, and pH were determined at regular time intervals. Plackett–Burman statistical methodology was adopted to study the effect of media components on xylanase production. The effect of temperature and pH was studied using optimized medium composition determined by Plackett–Burman experimental design. The maximum xylanase activity of 4.0 U ml−1 at 84 h at the optimum temperature of 35 °C and pH of 7.0 was obtained. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.

Bacillus sphaericus MTCC511 was used for the production of protease in submerged batch fermentation. Maximum protease activity of 1010 U/L was obtained during a fermentation period of 24 h under optimized conditions of 30 °C in a medium with an initial pH of 7 and at a shaking rate of 120 rpm. The maximum biomass obtained in the batch fermentation was 2.55 g/L after 16 h. Various unstructured models were analyzed to simulate the experimental values of microbial growth, protease activity and substrate concentration. The unstructured models, i.e. the Monod model for microbial growth, the Monod incorporated Luedeking-Piret model for the production of protease and the Monod-incorporated modified Luedeking-Piret model for the utilization of substrate were capable of predicting the fermentation profile with high coefficient of determination (R 2 ) values of 0.9967, 0.9402 and 0.9729, respectively. The results indicated that the unstructured models were able to describe the fermentation kinetics more effectively.

Additional file 1: Figure S1. ATR-FTIR spectra of the pure cultures (Chlorella vulgaris; Mucor sp.) and mycoalgae biofilm. Region 1 is the fatty acid region, Region 2 is the protein region, Region 3 is mixed region and Region 4 is polysaccharide region.

A sequential optimization approach using statistical design of experiments was employed to enhance the lipase production by Candida rugosa in submerged batch fermentation. Twelve medium components were evaluated initially using the Plackett–Burman 2-level factorial design. The significant variables affecting lipase production were found to be glucose, olive oil, peptone, (NH4)2SO4, and FeCl3·6H2O. Various vegetable oils were tested in the second step, and among them, groundnut oil was found to be the best inducer for lipase production by C. rugosa. The third step was to identify the optimal values of the significant medium components with groundnut oil as the inducer using response surface methodology. The regression equation obtained from the experimental data designed using a central composite design was solved, and analyzing the response surface contour plots, the optimal concentrations of the significant variables were determined. A maximum lipase activity of 5.95 U·mL–1, which is 1.64 times the maximum activity obtained in the Plackett–Burman experimental trials, was observed. The optimum combination of medium constituents contained 19.604 g·L–1glucose, 13.065 mL·L–1groundnut oil, 7.473 g·L–1peptone, 0.962 g·L–1(NH4)2SO4, 0.0019 g·L–1FeCl3·6H2O, and other insignificant components at the fixed level. A predictive model of the combined effects of the independent variables using response surface methodology and an artificial neural network was proposed. The unstructured kinetic models, logistic model, and Luedeking–Piret model were used to describe cell mass and lipase production. The parameters of the models were evaluated and the lipase production by C. rugosa was found to be growth associated.

A sequential optimization strategy with the aid of statistical design of experiments was used to enhance the lipase (triacylglycerol acylhydrolases, EC 3.1.1.3) production by Bacillus sphaericus in submerged cultivation. A Plackett–Burman experimental design was used to evaluate the twelve medium components. Various vegetable oil inducers were tested for lipase production in the second step and the third step was to identify the optimal values of the significant medium components with sesame oil as the inducer using response surface methodology. A predictive model of the combined effects of the independent variables using response surface methodology and an artificial neural network was proposed. Unstructured kinetic models, a logistic model and a Luedeking–Piret model, were used to describe the cell mass and lipase production respectively. The significant variables affecting lipase production were found to be glucose, olive oil, peptone, NaCl and MnSO4.H2O. Sesame oil was found to be the best inducer for lipase production by Bacillus sphaericus. The maximum lipase activity of 4.45 U mL−1, which was 1.5 times the maximum activity obtained in the Plackett–Burman experimental trials, was obtained at the optimum combination of medium constituents containing 12.695 g L−1 glucose, 13.161 mL L−1 sesame oil, 9.947 g L−1 peptone, 3.25 g L−1 NaCl, 0.5917 g L−1 MnSO4.H2O and other insignificant components at the fixed level. The statistical design of experiments offers an efficient methodology to identify the significant variables and to optimize the factors with a minimum number of experiments for lipase production by Bacillus sphaericus. Copyright © 2007 Society of Chemical Industry

The response surface optimization strategy was used to enhance the lipase production by Rhizopus arrhizus MTCC 2233 in submerged fermentation. Various vegetable oils were experimented as an inducer using the optimized medium to study the influence on lipase production, and corn oil was found to be the best inducer for lipase production by Rhizopus arrhizus. The optimization of fermentation conditions, temperature, initial pH and agitation speed was carried out using corn oil as the inducer. Statistical analysis of the experimental data showed that the temperature, agitation speed, quadratic effects of temperature, initial pH and agitation speed and interactive effects of temperature and agitation speed are significant parameters that affect lipase production. The optimum fermentation conditions were achieved at 32°C; pH 6.0 and agitation speed of 107 rpm with the maximum lipase activity of 4.32 U/mL. Artificial neural network model was used to predict the lipase activity and cell mass production under various fermentation conditions. Unstructured kinetic models, Logistic model, Luedeking-Piret model and modified Luedeking-Piret model were used to describe the cell biomass, lipase production and glucose utilization kinetics respectively.

L-Asparaginase is a therapeutic enzyme widely used as an antitumor agent for the treatment of acute lymphoblastic leukemia and lymphosarcoma. Its potential applications as a therapeutic agent and food additive require production at high yields in a low-cost medium with high purity and stability. Statistical experimental designs were applied to identify and optimize the significant parameters for the fermentative production of L-asparaginase by Pectobacterium carotovorum Microbial Type Culture Collection (MTCC) 1428. Screening of different carbon sources identified galactose as the best carbon source for the production of L-asparaginase. Twelve medium components were selected and sixteen experiments were carried out based on the Plackett–Burman (PB) design for identifying the most significant medium components. Yeast extract, galactose, monosodium glutamate, MgSO4.7H2O and CaCl2.2H2O were found to be the most significant components that affected the production of L-asparaginase, and they were optimized by response surface methodology (RSM) using central composite design. This optimized medium showed maximum production rates of periplasmic and extracellular L-asparaginase of 3.25 and 0.83 U ml−1, respectively. The periplasmic L-asparaginase production in the optimized medium was twofold higher than in the basal medium. Unstructured kinetic models were applied and satisfactorily described the cell growth, product formation and substrate utilization profile, thus providing a better understanding and prediction of the fermentation profile. This paper details the application of PB experimental design and RSM for the optimization of L-asparaginase production from Pe. carotovorum MTCC 1428 in submerged fermentation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

Lipase production by Candida rugosa was carried out in submerged fermentation. Plackett-Burman statistical experimental design was applied to evaluate the fermentation medium components. The effect of twelve medium components was studied in sixteen experimental trials. Glucose, olive oil, peptone and FeCl3.6H2O were found to have more significance on lipase production by Candida rugosa. Maximum lipase activity of 3.8 u mL(-1) was obtained at 50 h of fermentation period. The fermentation was carried out at optimized temperature of 30 degrees C, initial pH of 6.8 and shaking speed of 120 r/min. Unstructured kinetic models were used to simulate the experimental data. Logistic model, Luedeking-Piret model and modified Luedeking-Piret model were found suitable to efficiently predict the cell mass, lipase production and glucose consumption respectively with high determination coefficient(R2). From the estimated values of the Luedeking-Piret kinetic model parameters, alpha and beta, it was found that the lipase production by Candida rugosa is growth associated.

Background Microalgae is considered a promising source for biofuel and bioenergy production, bio-remediation and production of high-value bioactive compounds, but harvesting microalgae is a major bottleneck in the algae based processes. The objective of this research is to mimic the growth of natural lichen and develop a novel biofilm platform technology using filamentous fungi and microalgae to form a lichen type of biofilm “mycoalgae” in a supporting polymer matrix. Results The possibility of co-existence of Chlorella vulgaris with various fungal cultures was tested to identify the best strain combination for high algae harvest efficiency. The effect of different matrices for cell attachment and biofilm formation, cell surface characterization of mycoalgae biofilm, kinetics of the process with respect to the algae-fungi cell distribution and total biomass production was studied. Mycoalgae biofilm with algae attachment efficiency of 99.0 % and above was achieved in a polymer-cotton composite matrix with glucose concentration of 2 g/L in the growth medium and agitation intensity of 150 rpm at 27 °C. The total biomass in the co-culture with the selected strain combination (Mucor sp. and Chlorella sp.) was higher than the axenic cultures of fungi and algae at the conditions tested. Conclusions The results show that algae can be grown with complete attachment to a bio-augmenting fungal surface and can be harvested readily as a biofilm for product extraction from biomass. Even though, interaction between heterotrophic fungi and phototrophic algae was investigated in solid media after prolonged contact in a report, this research is the first of its kind in developing an artificial lichen type biofilm called “mycoalgae” biofilm completely attached on a matrix in liquid cultures. The mycoalgae biofilm based processes, propounds the scope for exploring new avenues in the bio-production industry and bioremediation. Electronic supplementary material The online version of this article (doi:10.1186/s13068-016-0533-y) contains supplementary material, which is available to authorized users.