Corn steep liquor as a nutrition adjunct for the production of Aspergillus niger lipase and hydrolysis of oils thereof

The Formation of Starch-Lipid Inclusion Complex by Enzymatic Hydrolysed Oils

This study aimed to investigate the enzymatic hydrolysis of sunflower, olive, and flaxseed oils and its impact on starch complexation and properties. Enzymatic treatment significantly increased free fatty acid content to 45% without any significant change in fatty acid composition and oxidation precursors. The complexation of high amylose maize starch with hydrolysed flaxseed oil was effective in limiting starch digestion. The highest resistant starch content and expected glycemic index value were determined in starch lipid complex formed by hydrolysed flaxseed oil to be 69.11% and 56.44, respectively. According to XRD patterns, V-type formation was obtained only in complexes formed by hydrolysed oils. Overall, it is concluded that enzymatic hydrolysis of polyunsaturated triglyceride fatty acids to free fatty acids and subsequent complexation with starch can be effective in the production of RS5.

Optimization of Medium Composition and Fluidized Bed Drying Conditions for Efficient Production of Dry Yeast

Yeast formulations such as dry yeast are essential for supplying microbial starters to the alcoholic beverage industry. In Korea, the expensive freeze-drying method is used to manufacture brewer's dry yeast, and therefore an economical process such as fluidized bed drying is needed. In the dry yeast manufacturing process, the medium and drying conditions are key factors that determine its quality and manufacturing cost. In this study, we aimed to optimize the medium composition and fluidized bed drying conditions for the efficient production of dry yeast. Muscovado and corn steep liquor were used as the carbon and nitrogen sources, respectively, and their optimal concentrations were identified using response surface methodology for efficient cultivation of Saccharomyces cerevisiae ReY4-7 isolated from nuruk. Central composite design analysis revealed that the optimal medium composition was 146.12 g/L muscovado and 58.68 g/L corn steep liquor. A dry cell weight of 36 g/L was achieved during 24 h of batch fermentation in a 30-L bioreactor containing this medium. Analysis of protective agents against fluidized bed drying revealed Span 80 as the strongest protective agent for S. cerevisiae ReY4-7. Response surface methodology revealed 50 °C and 41.45 min as the optimal fluidized bed drying conditions, under which the viable cell count reached 10.28 log CFU/g, comparable to that of the commercial dry yeast products. Overall, optimization of the medium and drying conditions significantly improved the final cell concentration in the cultivation process and the viable cell count in the drying process of dry yeast.

Strain engineering of Bacillus coagulans with high osmotic pressure tolerance for effective L-lactic acid production from sweet sorghum juice under unsterile conditions

Open unsterile fermentation of the low-cost non-food crop, sweet sorghum, is an economically feasible lactic acid biosynthesis process. However, hyperosmotic stress inhibits microbial metabolism and lactic acid biosynthesis, and engineering strains with high osmotic tolerance is challenging. Herein, heavy ion mutagenesis combined with osmotic pressure enrichment was used to engineer a hyperosmotic-tolerant Bacillus coagulans for L-lactic acid production. The engineered strain had higher osmotic pressure tolerance, when compared with the parental strain, primarily owing to its improved properties such as cell viability, cellular antioxidant capacity, and NADH supply. In a pilot-scale open unsterile fermentation using sweet sorghum juice as a feedstock, the engineered strain produced 94 g/L L-lactic acid with a yield of 91 % and productivity of 6.7 g/L/h, and optical purity of L-lactic acid at the end of fermentation was 99.8 %. In short, this study provided effective and low-cost approach to produce polymer-grade L-lactic acid.

Improved Cordycepin Production by Cordyceps Militaris Using Corn Steep Liquor Hydrolysate as an Alternative Protein Nitrogen Source

Cordycepin production in the submerged culture of Cordyceps militaris was demonstrated using hydrolyzed corn processing protein by-products, known as corn steep liquor hydrolysate (CSLH), as an alternative nitrogen source. The growth, metabolism, and cordycepin production of Cordyceps militaris were evaluated under various concentrations of CSLH induction. The results demonstrated that CSLH addition had positive effects on the growth and cordycepin production with various C. militaris strains. The optimum strain, C. militaris GDMCC5.270, was found to effectively utilize CSLH to promote mycelium growth and cordycepin production. Low concentrations of CSLH (1.5 g/L) in the fermentation broth resulted in 343.03 ± 15.94 mg/L cordycepin production, which was 4.83 times higher than that of the group without CSLH. This also enhanced the metabolism of sugar, amino acids, and nucleotides, leading to improved cordycepin biosynthesis. The increase in key amino acids, such as glutamic acid, alanine, and aspartic acid, in the corn steep liquor hydrolysate significantly enhanced cordycepin yield. The corn steep liquor hydrolysate was confirmed to be a cost-effective accelerator for mycelium growth and cordycepin accumulation in C. militaris, replacing partial peptone as a cheap nitrogen source. It serves as a suitable alternative for efficient cordycepin production at a low cost.

Unraveling the potential and constraints associated with corn steep liquor as a nutrient source for industrial fermentations

Costly complex media components such as yeast extract and peptone are still widely used in industrial bioprocesses, despite their ill-defined composition. Side stream products such as corn steep liquor (CSL) present a compelling economical alternative that contains valuable nutrients required for microbial growth, that is, nitrogen and amino acids, but also vitamins, trace elements, and other minerals. However, as a side stream product, CSL may be subject to batch-to-batch variations and compositional heterogeneity. In this study, the Respiration Activity MOnitoring System designed for shake flasks (RAMOS) and 96-well microtiter plates (μTOM) were applied to investigate the potential and constraints of CSL utilization for two model microorganisms: E. coli and B. subtilis. Considering the dry substance content of complex nutrients involved, CSL-based media are more efficient in biomass production than the common lysogeny broth (LB) medium, containing 5 g/L yeast extract, 10 g/L peptone, and 5 g/L NaCl. At a glucose to CSL (glucose/CSL, g/g) ratio of 1/1 (g/g) and 2/1 (g/g), a secondary substrate limitation occurred in E. coli and B. subtilis cultivations, respectively. The study sheds light on differences in the metabolic activity of the two applied model organisms between varying CSL batches, which relate to CSL origin and production process, as well as the effect of targeted nutrient supplementation. Through a targeted nutrient supplementation, the most limiting component of the CSL-glucose medium used for these applied model microorganisms was identified to be ammonium nitrogen. This study proves the suitability of CSL as an alternative nutrient source for E. coli and B. subtilis. The RAMOS and μTOM technique detected differences between CSL batches, allowing easy and early identification of varying batches. A consistent performance of the CSL batches in E. coli and B. subtilis cultivations was demonstrated.

Corn Steep Liquor: Green Biological Resources for Bioindustry

Corn steep liquor (CSL) is a by-product of the wet milling process and contains mostly crude proteins, amino acids, minerals, vitamins, reducing sugars, organic acids, enzymes and other nutrients. The concentration of organic matter in the CSL is high and the yield is large. If directly discharged into the integrated wastewater treatment system, the load and cost of wastewater treatment will be greatly increased. On the other hand, most of the organic matter in the CSL is a valuable resource that can be reused and recovered, and has a significant resource potential. How to develop and utilize CSL has become a major problem faced by enterprises and society. In recent years, people have done a lot of research on the comprehensive utilization of CSL. CSL is commonly used as an inexpensive source of nitrogen, carbon or vitamins in the production of glutamate, antibiotics, lactic acid and other biotechnologies. This article reviews the active ingredients of CSL and their analytical methods, as well as its use for microbial culture medium, low-cost animal feed, biosurfactant, and biostimulant.

Sustainable Lipase Production by Diutina rugosa NRRL Y-95 Through a Combined Use of Agro-Industrial Residues as Feedstock

The potential use of alternative culture media towards the development of a sustainable bioprocess to produce lipases by Diutina rugosa is clearly demonstrated. First, a synthetic medium containing glucose, peptone, yeast extract, oleic acid, and ammonium sulfate was proposed, with lipase activity of 143 U/L. Then, alternative culture media formulated with agro-industrial residues, such as molasses, corn steep liquor (CSL), and olive mill waste (OMW), were investigated. An experimental design was conducted, and only CSL concentration was found to have a positive effect in lipase production. The highest lipase activity (561 U/L) was produced on a mixture of molasses (5 g/L), CSL (6 g/L), OMW (0.5% v/v), 0.5 g/L of ammonium sulfate, and 3 g/L of peptone at 24 h of cultivation. Lipase production was also carried out in a 1-L bioreactor leading to a slightly higher lipase activity at 24 h of cultivation. The semi-purified enzyme exhibits an optimum temperature and pH of 40 °C and 7.0, respectively. Finally, the media cost per unit of lipase produced (UPC) was influenced by the medium components, specially by the inducer used. The lowest UPC was obtained when the agro-industrial residues were combined and used at the improved concentrations.

One Pot Use of Combilipases for Full Modification of Oils and Fats: Multifunctional and Heterogeneous Substrates

Lipases are among the most utilized enzymes in biocatalysis. In many instances, the main reason for their use is their high specificity or selectivity. However, when full modification of a multifunctional and heterogeneous substrate is pursued, enzyme selectivity and specificity become a problem. This is the case of hydrolysis of oils and fats to produce free fatty acids or their alcoholysis to produce biodiesel, which can be considered cascade reactions. In these cases, to the original heterogeneity of the substrate, the presence of intermediate products, such as diglycerides or monoglycerides, can be an additional drawback. Using these heterogeneous substrates, enzyme specificity can promote that some substrates (initial substrates or intermediate products) may not be recognized as such (in the worst case scenario they may be acting as inhibitors) by the enzyme, causing yields and reaction rates to drop. To solve this situation, a mixture of lipases with different specificity, selectivity and differently affected by the reaction conditions can offer much better results than the use of a single lipase exhibiting a very high initial activity or even the best global reaction course. This mixture of lipases from different sources has been called “combilipases” and is becoming increasingly popular. They include the use of liquid lipase formulations or immobilized lipases. In some instances, the lipases have been coimmobilized. Some discussion is offered regarding the problems that this coimmobilization may give rise to, and some strategies to solve some of these problems are proposed. The use of combilipases in the future may be extended to other processes and enzymes.

High-Yield Production of Lycopene from Corn Steep Liquor and Glycerol Using the Metabolically Engineered Deinococcus radiodurans R1 Strain

Developing a highly efficient and ecofriendly system to produce desired products from waste can be considered important to a sustainable society. Here, we report for the first time high-yield production of lycopene through metabolically engineering an extremophilic microorganism, Deinococcus radiodurans R1, from corn steep liquor (CSL) and glycerol. First, the crtLm gene-encoding lycopene cyclase was deleted to prevent the conversion of lycopene to γ-carotene. Then, the crtB gene-encoding phytoene synthase and the dxs gene-encoding 1-deoxy-d-xylulose 5-phosphate synthase were overexpressed to increase carbon flux toward lycopene. The engineered ΔcrtLm/crtB⁺dxs⁺ D. radiodurans R1 could produce 273.8 mg/L [80.7 mg/g dry cell weight (DCW)] and 373.5 mg/L (108.0 mg/g DCW) of lycopene from 10 g/L of glucose with 5 g/L of yeast extract and 9.9 g/L of glucose with 20 g/L of CSL, respectively. Moreover, the lycopene titer and content were increased by 26% (470.6 mg/L) and 28% (138.2 mg/g DCW), respectively, when the carbon source was changed to glycerol. Finally, fed-batch fermentation of the final engineered strain allowed the production of 722.2 mg/L (203.5 mg/g DCW) of lycopene with a yield and productivity of 20.3 mg/g glycerol and 6.0 mg/L/h, respectively, from 25 g/L of CSL and 35.7 g/L of glycerol.

Co-valorization of paper mill sludge and corn steep liquor for enhanced n-butanol production with Clostridium tyrobutyricum Δcat1::adhE2

In this study, hyper-butanol producing Clostridium tyrobutyricum Δcat1::adhE2 was used for butanol production from paper mill sludge (PMS) and corn steep liquor (CSL). Our results demonstrated that CSL can not only serve as a cheap nitrogen source, but also provide lactic acid that can be assimilated by C. tyrobutyricum for enhanced butanol production. Through a separate hydrolysis and fermentation, 16.5 g/L butanol with a yield of 0.26 g/g was obtained from PMS hydrolysates supplemented with 5% CSL. Further, a separate repeated hydrolysis was conducted to improve PMS hydrolysis rate and enhance sugar yield. Fermentation using hydrolysates from such process also generated high-level butanol with high yield. Our results suggested an innovative bioprocess for efficient biobutanol production from low-value waste streams.

Lipolytic Enzymes with Hydrolytic and Esterification Activities Produced by Filamentous Fungi Isolated from Decomposition Leaves in an Aquatic Environment

Microbial lipases are prominent biocatalysts able to catalyze a wide variety of reactions in aqueous and nonaqueous media. In this work, filamentous fungi isolated from leaves decomposed in an aquatic environment were screened for lipase production with hydrolytic activity and esterification. Agar plates with Tween 20 and Rhodamine B were used for selection, while submerged cultures with olive oil were subsequently used to select 38 filamentous fungi. Trichoderma harzianum, Fusarium solani, Trichoderma harzianum F5, and Penicillium sp. F36 were grown in six different culture media. F. solani presented the highest lipase production (2.37 U/mL) with esterification activity of 0.07 U/mL using medium composed of (g.L-1) KH2PO4 1.00, MgSO4 H2O 1.123, and CuSO4 0.06. Supplementation of this culture medium with organic nitrogen sources increased lipase production by 461.3% using tryptone and by 419.4% using yeast extract. Among the vegetable oils from the Amazon region, degummed cotton oil induced lipase production up to 8.14 U/mL. The lipase produced by F. solani F61 has great potential to application in conventional processes and biodiesel production by transesterification of vegetable oils, as well as food industries in the production of fatty acid esters by hydrolysis and esterification.

Microbial biodegradation of proteinaceous tannery solid waste and production of a novel value added product - Metalloprotease

In this study, animal fleshing (ANFL) was utilized as a substrate for the production of extracellular protease by Clostridium limosum through central composite rotatable design (CCRD) and response surface methodology (RSM). Optimum protease production of 433U/ml was achieved and the purified enzyme was identified as acidic metalloprotease, a monomeric protein. The molecular weight of the enzyme was 71kDa, whose activity was enhanced by bivalent metals such as Zn(2+) and Mg(2+). Scanning electron microscopy (SEM) examination also revealed the hydrolysis/microbial degradation of ANFL through protease activity in the anaerobic fermentation process. Simultaneous hydrolysis of ANFL and production of an enzyme with the potential for different industrial applications provide an attractive methodology for the disposal of tannery solid waste.

Green conversion of agroindustrial wastes into chitin and chitosan by Rhizopus arrhizus and Cunninghamella elegans strains

This article sets out a method for producing chitin and chitosan by Cunninghamella elegans and Rhizopus arrhizus strains using a green metabolic conversion of agroindustrial wastes (corn steep liquor and molasses). The physicochemical characteristics of the biopolymers and antimicrobial activity are described. Chitin and chitosan were extracted by alkali-acid treatment, and characterized by infrared spectroscopy, viscosity and X-ray diffraction. The effectiveness of chitosan from C. elegans and R. arrhizus in inhibiting the growth of Listeria monocytogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica, Escherichia coli and Yersinia enterocolitica were evaluated by determining the minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC). The highest production of biomass (24.60 g/L), chitin (83.20 mg/g) and chitosan (49.31 mg/g) was obtained by R. arrhizus. Chitin and chitosan from both fungi showed a similar degree of deacetylation, respectively of 25% and 82%, crystallinity indices of 33.80% and 32.80% for chitin, and 20.30% and 17.80% for chitosan. Both chitin and chitosan presented similar viscosimetry of 3.79–3.40 cP and low molecular weight of 5.08 × 10³ and 4.68 × 10³ g/mol. They both showed identical MIC and MBC for all bacteria assayed. These results suggest that: agricultural wastes can be produced in an environmentally friendly way; chitin and chitosan can be produced economically; and that chitosan has antimicrobial potential against pathogenic bacteria.

Determination of main categories of components in corn steep liquor by near-infrared spectroscopy and partial least-squares regression

Corn steep liquor (CSL) is an important raw material that has a high nutritional value and serves as a nitrogen source. This study aimed to develop a fast, versatile, cheap, and environmentally safe analytical method of quantifying the total acidity (TA) of CSL as well as its contents of dry matter (DM), total sugars (TS), total reducing sugars (TRS), total free amino acids (TFAA), total nitrogen (TN), and total sulfite (TSu). The near-infrared (NIR) spectroscopy measurements of 66 samples (22 batches) of CSL were analyzed by partial least-squares regression using several spectral preprocessing methods. Multivariate models developed in the NIR area showed good predictive abilities for DM, TA, TS, TRS, TFAA, TN, and TSu determination. These results confirm the feasibility of the multivariate spectroscopic approach as a replacement for expensive and time-consuming conventional chemical methods. Thus, a convenient and feasible method for the quality control of fermentation raw materials for food additives and fine chemicals, especially in CSL, is established.

Lipase applications in oil hydrolysis with a case study on castor oil: a review

Lipase (triacylglycerol acylhydrolase) is a unique enzyme which can catalyze various types of reactions such as hydrolysis, esterification, alcoholysis etc. In particular, hydrolysis of vegetable oil with lipase as a catalyst is widely studied. Free lipase, lipase immobilized on suitable support, lipase encapsulated in a reverse micelle and lipase immobilized on a suitable membrane to be used in membrane reactor are the most common ways of employing lipase in oil hydrolysis. Castor oil is a unique vegetable oil as it contains high amounts (90%) of a hydroxy monounsaturated fatty acid named ricinoleic acid. This industrially important acid can be obtained by hydrolysis of castor oil. Different conventional hydrolysis processes have certain disadvantages which can be avoided by a lipase-catalyzed process. The degree of hydrolysis varies widely for different lipases depending on the operating range of process variables such as temperature, pH and enzyme loading. Immobilization of lipase on a suitable support can enhance hydrolysis by suppressing thermal inactivation and estolide formation. The presence of metal ions also affects lipase-catalyzed hydrolysis of castor oil. Even a particular ion has different effects on the activity of different lipases. Hydrophobic organic solvents perform better than hydrophilic solvents during the reaction. Sonication considerably increases hydrolysis in case of lipolase. The effects of additives on the same lipase vary with their types. Nonionic surfactants enhance hydrolysis whereas cationic and anionic surfactants decrease it. A single variable optimization method is used to obtain optimum conditions. In order to eliminate its disadvantages, a statistical optimization method is used in recent studies. Statistical optimization shows that interactions between any two of the following pH, enzyme concentration and buffer concentration become significant in presence of a nonionic surfactant named Span 80.

Comprehensive quality evaluation of corn steep liquor in 2-keto-L-gulonic acid fermentation

Corn steep liquor (CSL) is one of the main raw materials in 2-keto-L-gulonic acid (2-KLG) fermentation by Ketogulonicigenium vulgare and Bacillus megaterium . Due to its natural origin and variations in the manufacturing process, unpredicted and uncontrolled variability of CSL has a great influence on 2-KLG production; however, conventional quality specifications are not enough to ensure stability of fermentation behaviors. A process analytical technology (PAT) could be considered to explore the relationship between CSL quality and 2-KLG production comprehensively. The compositions of CSL from six manufacturers were profiled by gas chromatography with time-of-flight mass spectrometry (GC-TOFMS) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES), combined with orthogonal partial least-squares discriminant analysis (OPLS-DA). Seventeen components were identified as the most discriminant marker compounds related to 2-KLG production. Results revealed that they were responsible for providing nutrients and protecting osmotic pressure. Furthermore, nine amino acids were verified as potential group markers by addition to the medium and demonstration of the correlation to 2-KLG production. The comprehensive approach provided an important platform to explore CSL marker compounds for quality evaluation in 2-KLG fermentation.

Selection of lipase producing yeasts for methanol-tolerant biocatalyst as whole cell application for palm-oil transesterification

Methanol-tolerant lipase producing yeast was successfully isolated and selected thorough ecological screening using palm oil-rhodamine B agar as one step-approach. All 49 lipase-producing yeasts exhibited the ability to catalyze esterification reaction of oleic acid and methanol at 3 molar equivalents. However, only 16 isolates catalyzed transesterification reaction of refined palm oil and methanol. Rhodotorula mucilagenosa P11I89 isolated from oil contaminated soil showed the strongest hydrolytic lipase activity of 1.2U/ml against palm oil. The production of oleic methyl ester and fatty acid methyl ester (FAME) of 64.123 and 51.260% was obtained from esterification and transesterification reaction catalyzed by whole cell of R. mucilagenosa P11I89 in the presence of methanol at 3 molar equivalents against the substrates, respectively. FAME content increased dramatically to 83.29% when 6 molar equivalents of methanol were added. Application of the methanol-tolerant-lipase producing yeast as a whole cell biocatalyst was effectively resolved major technical obstacles in term of enzyme stability and high cost of lipase, leading to the feasibility of green biodiesel industrialization.

Study of Soybean Oil Hydrolysis Catalyzed by Thermomyces lanuginosus Lipase and Its Application to Biodiesel Production via Hydroesterification

The process of biodiesel production by the hydroesterification route that is proposed here involves a first step consisting of triacylglyceride hydrolysis catalyzed by lipase from Thermomyces lanuginosus (TL 100L) to generate free fatty acids (FFAs). This step is followed by esterification of the FFAs with alcohol, catalyzed by niobic acid in pellets or without a catalyst. The best result for the enzyme-catalyzed hydrolysis was obtained under reaction conditions of 50% (v/v) soybean oil and 2.3% (v/v) lipase (25 U/mL of reaction medium) in distilled water and at 60°C; an 89% conversion rate to FFAs was obtained after 48 hours of reaction. For the esterification reaction, the best result was with an FFA/methanol molar ratio of 1:3, niobic acid catalyst at a concentration of 20% (w/w FFA), and 200°C, which yielded 92% conversion of FFAs to soy methyl esters after 1 hour of reaction. This study is exceptional because both the hydrolysis and the esterification use a simple reaction medium with high substrate concentrations.

Scale up of a novel tri-substrate fermentation for enhanced production of Aspergillus niger lipase for tallow hydrolysis

A novel tri-substrate fermentation (TSF) process was developed for the production of lipase from Aspergillus niger MTCC 2594 using agro-industrial residues, wheat bran (WB), coconut oil cake (COC) and an agro-product, wheat rawa (WR). The lipase activity was 628.7+/-13 U/g dry substrate (U/gds) at 30 degrees C and 96 h and growth studies indicated that addition of WR significantly augmented the biomass and lipase production. Scale up of lipase production at 100g and 3 kg (3 x 1 kg) tray-level batch fermentation resulted in 96% and 83.0% of enzyme activities, respectively, at 72 h. Maximum activity of 745.7+/-11U/gds was obtained, when fermented substrate was extracted in buffer containing 1% (w/v) sodium chloride and 0.5% (w/v) Triton X-100. Furthermore, the direct application of fermented substrate for tallow hydrolysis makes the process economical for industrial production of biofuel.