Response surface methodology-based optimization of production media and purification of α-galactosidase in solid-state fermentation by Fusarium moniliforme NCIM 1099

Recombinant expression and characterization of an α-galactosidase from Thermoclostridium stercorarium subsp. thermolacticum DSM 2910 and its application in the hydrolysis of raffinose

Soybean contains anti-nutritional factor raffinose oligosaccharide (RFOs), which can cause flatulence, gastrointestinal dysfunction and low feed utilization rate. However, α-galactosidase can hydrolyze raffinose oligosaccharides (RFOs). Therefore, in this study, a novel α-galactosidase from Thermoclostridium stercorarium subsp. thermolacticum DSM 2910 (TstGal) which can hydrolyze raffinose was cloned, expressed, purified, and characterized. The gene fragment size is 2208 bp, and the enzyme TstGal consists of 736 amino acids. Under the optimum culture conditions, the maximum enzyme activity of the target protein TstGal was 23.8 U/mL. The enzyme was purified 11.3-fold by Ni-NTA agarose resin with an overall recovery of 51.4 % and specific activity of 9.0 U/mg, and its relative molecular weight was about 85 kDa. The optimal temperature of TstGal was 70 °C, and it exhibited excellent thermal stability at 60 °C. Furthermore, The TstGal had the highest activity at pH 6.5 and good pH stability at pH 5.0-7.5. Besides, the enzyme has a good sugar tolerance to galactose and sucrose. In addition, K+ and Fe2+ could significantly enhance the enzyme activity at a concentration of 5 mM. The values of KM, Vmax, kcat, and kcat/KM for pNPGal were found to be 0.507 mM, 13.979 U/mg, 19.735 s-1, and 38.895 s-1mM-1, respectively. Under the optimum conditions, the maximum hydrolysis rate of raffinose by TstGal reached 99.8 %, which shows that the enzyme had potential application value in food and feed industry.

Enhancement of α-galactosidase production using novel Actinoplanes utahensis B1 strain: sequential optimization and purification of enzyme

α-Galactosidase is an important exoglycosidase belonging to the hydrolase class of enzymes, which has therapeutic and industrial potential. It plays a crucial role in hydrolyzing α-1,6 linked terminal galacto-oligosaccharide residues such as melibiose, raffinose, and branched polysaccharides such as galacto-glucomannans and galactomannans. In this study, Actinoplanes utahensis B1 was explored for α-galactosidase production, yield improvement, and activity enhancement by purification. Initially, nine media components were screened using the Plackett-Burman design (PBD). Among these components, sucrose, soya bean flour, and sodium glutamate were identified as the best-supporting nutrients for the highest enzyme secretion by A. Utahensis B1. Later, the Central Composite Design (CCD) was implemented to fine-tune the optimization of these components. Based on sequential statistical optimization methodologies, a significant, 3.64-fold increase in α-galactosidase production, from 16 to 58.37 U/mL was achieved. The enzyme was purified by ultrafiltration-I followed by multimode chromatography and ultrafiltration-II. The purity of the enzyme was confirmed by Sodium Dodecyl Sulphate-Polyacrylamide Agarose Gel Electrophoresis (SDS-PAGE) which revealed a single distinctive band with a molecular weight of approximately 72 kDa. Additionally, it was determined that this process resulted in a 2.03-fold increase in purity. The purified α-galactosidase showed an activity of 2304 U/mL with a specific activity of 288 U/mg. This study demonstrates the isolation of Actinoplanes utahensis B1 and optimization of the process for the α-galactosidase production as well as single-step purification.

Covalent immobilization of β-galactosidase using a novel carrier alginate/tea waste: statistical optimization of beads modification and reusability

β-galactosidase has been immobilized onto novel alginate/tea waste gel beads (Alg/TW) via covalent binding. Alg/TW beads were subjected to chemical modification through amination with polyethyleneimine (PEI) followed by activation with glutaraldehyde (GA). Chemical modification parameters including PEI concentration, PEI pH, and GA concentration were statistically optimized using Response Surface methodology (RSM) based on Box-Behnken Design (BBD). Analysis of variance (ANOVA) results confirmed the great significance of the model that had F value of 37.26 and P value < 0.05. Furthermore, the R2 value (0.9882), Adjusted R2 value (0.9617), and predicted R2 value (0.8130) referred to the high correlation between predicted and experimental values, demonstrating the fitness of the model. In addition, the coefficient of variation (CV) value was 2.90 that pointed to the accuracy of the experiments. The highest immobilization yield (IY) of β-galactosidase (75.1%) was given under optimized conditions of PEI concentration (4%), PEI pH (9.5), and GA concentration (2.5%). Alg/TW beads were characterized by FT-IR, TGA, and SEM techniques at each step of immobilization process. Moreover, the immobilized β-galactosidase revealed a very good reusability as it could be reused for 15 and 20 consecutive cycles keeping 99.7 and 72.1% of its initial activity, respectively. In conclusion, the environmental waste (tea waste) can be used in modern technological industries such as the food and pharmaceutical industry.

Characterization of a fungal α-galactosidase and its synergistic effect with β-mannanase for hydrolysis of galactomannan

An acid stable α-galactosidase was produced and purified from mannolytic fungal strain, Penicillium aculeatum APS1. Enzyme was produced using wheat bran and copra cake moistened with corn steep liquor by solid state fermentation. APS1αgal having molecular weight of 65.4 kDa was purified to electrophoretic homogeneity by three phase partitioning and gel permeation chromatography with high enzyme recovery. APS1αgal was found to be maximally active at 55 °C and pH 4.5, having high stability at acidic pH. Thermal stability and thermal inactivation kinetics of APS1αgal were also studied. APS1αgal was found to effectively hydrolyse oligosaccharides as well as polysaccharides having α-1,6 linked galactose. Abolishment of enzyme activity in N-brommosuccinimide revealed an important role of tryptophan residue in catalysis. APS1αgal had shown outstanding tolerance to NaCl and proteases. MALDI-TOF MS/MS analysis indicated that enzyme is probably a member of family GH27. Synergistic interaction between APS1αgal and β-mannanase for hydrolysis of galactomannan was very clear and maximum 2.0° of synergy was found under simultaneous mode of action. This study reports a new source of α-galactosidase with biochemical properties suitable for applications in food and feed industries.

Homoscleromorpha-derived Bacillus spp. as potential sources of biotechnologically-relevant hydrolases and biosurfactants

Despite hydrolytic exoenzymes and biosurfactants having been gradually reported from the poriferan microbiome, little is known about these bioproducts in microorganisms inhabiting Homoscleromorpha sponges. Here, we investigated the production of hydrolases and biosurfactants in bacteria isolated from three shallow-water homoscleromorph species, Oscarella sp., Plakina cyanorosea, and Plakina cabofriense. A total of 99 of 107 sponge-associated bacterial isolates exhibited activity for at least one of the analyzed hydrolases. Following fermentation in Luria-Bertani (LB) and Tryptic Soy Broth (TSB), two isolates, 80BH11 and 80B1:1010b, showed higher lipase and peptidase activities. Both of them belonged to the Bacillus genus and were isolated from Oscarella. Central composite design leveraged up the peptidase activity in 280% by Bacillus sp. 80BH11 in the TSB medium for 48 h at 30 °C. The optimized model also revealed that pH 6.5 and 45 °C were the best conditions for peptidase reaction. In addition, Bacillus sp. 80BH11 was able to release highly emulsifying and remarkably stable surfactants in the LB medium. Surfactin was finally elucidated as the biosurfactant generated by this sponge-derived Bacillus. In conclusion, we hope to have set the scenery for further prospecting of industrial enzymes and biosurfactants in Homoscleromorpha microbiomes.

A statistical strategy for optimizing the production of α-galactosidase by a newly isolated Aspergillus niger NRC114 and assessing its efficacy in improving soymilk properties

Background

α-Galactosidase is widely distributed in plants, microorganisms, and animals, and it is produced by different fungal sources. Many studies have confirmed the valuable applications of α-galactosidase enzymes for various biotechnological purposes, like the processing of soymilk.

Results

Aspergillus niger NRC114 was exploited to produce the extracellular α-galactosidase. One factor per time (OFT) and central composite design (CCD) approaches were applied to determine the optimum parameters and enhance the enzyme production. The CCD model choices of pH 4.73, 1.25% mannose, 0.959% meat extract, and 6-day incubation period have succeeded in obtaining 25.22 U/mL of enzyme compared to the 6.4 U/mL produced using OFT studies. Treatment of soymilk by α-galactosidase caused an increase in total phenols and flavonoids by 27.3% and 19.9%, respectively. Antioxidant measurements revealed a significant increase in the enzyme-treated soymilk. Through HPLC analysis, the appearance of sucrose, fructose, and glucose in the enzyme-treated soymilk was detected due to the degradation of stachyose and raffinose. The main volatile compounds in raw soymilk were acids (45.04%) and aldehydes (34.25%), which showed a remarkable decrease of 7.82% and 20.03% after treatment by α-galactosidase.

Conclusions

To increase α-galactosidase production, the OFT and CCD approaches were used, and CCD was found to be four times more effective than OFT. The produced enzyme proved potent enough to improve the properties of soymilk, avoiding flatulence and undesirable tastes and odors.

Graphical Abstract

Microbial α-galactosidases: Efficient biocatalysts for bioprocess technology

Galactomannans, abundantly present in plant biomass, can be used as renewable fermentation feedstock for biorefineries working for the production of bioethanol and other value-added products. The complete and efficient bioconversion of biomass to fermentable sugars for the generation of biofuels and other value-added products require the concerted action of accessory enzymes like α-galactosidases, which can work in cohesion with other carbohydrases in an enzyme cocktail. In the paper industry, α-galactosidases enhance the bleaching effect of endo-β-1,4-mannanases on softwood kraft pulp. Microbial α-galactosidases also find applications in the treatment of legume foods, recovery of sucrose from sugar beet syrup, improving the rheological properties of galactomannans, and synthesis of α-galactooligosaccharides to be used as functional food ingredients. Owing to their industrial applications, there is a surge in the research focused on α-galactosidases. The current review illustrates the diverse industrial applications of microbial α-galactosidases and their challenges and prospects.

Insights on sustainable approaches for production and applications of value added products

The increasing demand for the development of sustainable strategies to utilize and process agro-industrial residues paves new paths for exploring innovative approaches in this area. Biotechnology based microbial transformations provide efficient, low cost and sustainable approaches for the production of value added products. The use of organic rich residues opens new avenues for the production of enzymes, pigments, biofuels, bioactive compounds, biopolymers etc. with vast industrial and therapeutic applications. Innovative technologies like strain improvement, enzyme immobilization, genome editing, morphological engineering, ultrasound/supercritical fluid/pulse electric field extraction, etc. can be employed. These will be helpful in achieving significant improvement in qualitative and quantitative parameters of the finished products. The global trend for the valorisation of biowaste has boosted the commercialization of these products which has transformed the markets by providing new investment opportunities. The upstream processing of raw materials using microbes poses a limitation in terms of product development and recovery which can be overcome by modifying the bioreactor design, physiological parameters or employing alternate technologies which will be discussed in this review. The other problems related to the processes include product stability, industrial applicability and cost competitiveness which needs to be addressed. This review comprehensively discusses the recent progress, avenues and challenges in the approaches aimed at valorisation of agro-industrial wastes along with possible opportunities in the bioeconomy.

One-pot production of lactic acid from rice straw pretreated with ionic liquid

Production of platform chemicals has been advocated as a sustainable option to tackle the problems associated with agro-waste management. In this report, for the first time, efforts were made to effectively produce second-generation lactic acid from rice straw pretreated with imidazolium ionic liquid [EMIM][OAc] and subsequently fermented with a promising Lactobacillus plantarum SKL-22 strain saccharified with a commercial cellulase enzyme. Medium optimization was carried out to enhance the lactic acid (LA) yield by response surface methodology. In a 5 L bioreactor, the process was further upscale, and a yield increment of 1.11% was observed. The process using rice straw as substrate led to a LA yield of 36.75 g/L from L. plantarum SKL-22 in a single pot bioprocess. Overall, the above finding has shown the ability of L. plantarum SKL-22 to produce LA from the hydrolysate of rice straw. This study presented a novel environmental-friendly method for LA production.

Production, purification and application of Cutinase in enzymatic scouring of cotton fabric isolated from Acinetobacter baumannii AU10

Conventional cotton scouring in the textile industry using alkali results in huge environmental impact which can be overcome by using enzymes. Pectinase along with cutinase gives enhanced bioscouring results. Cutin was extracted from tomato peels and was used as substrate in the microbial media. The strain isolated from tomato peel was identified as Acinetobacter baumannii AU10 by 16S rDNA sequencing. The cutinase production was optimized by Placket-Burman and Response Surface Methodology (RSM) and the maximum production of 82.75 U/mL obtained at sucrose 6.68% (w/v), gelatin 2.74 g/L at a temperature of 35.93 °C. Cutinase was purified by ammonium sulfate precipitation, hydrophobic interaction chromatography and ion exchange chromatography with a recovery of 25.6% and specific activity of 38030 U/mg. The confirmation test for the purity of cutinase was analyzed by RP-HPLC. The molecular mass of cutinase was determined as 28.9 kDa by SDS-PAGE technique. Scanning electron microscopic analysis showed a rough and open primary wall surface on the cutinase bioscoured fabric which confirmed its activity on cutin present in the cotton fabric. Additionally, the cutinase-bioscoured samples showed better absorbency than the untreated samples. Therefore, enzymatic scouring increases wetting capacity of scoured cotton and also helps to reduce environmental pollution.

Optimization of Saccharomyces cerevisiae α-galactosidase production and application in the degradation of raffinose family oligosaccharides

BACKGROUND

α-Galactosidases are enzymes that act on galactosides present in many vegetables, mainly legumes and cereals, have growing importance with respect to our diet. For this reason, the use of their catalytic activity is of great interest in numerous biotechnological applications, especially those in the food industry directed to the degradation of oligosaccharides derived from raffinose. The aim of this work has been to optimize the recombinant production and further characterization of α-galactosidase of Saccharomyces cerevisiae.

RESULTS

The MEL1 gene coding for the α-galactosidase of S. cerevisiae (ScAGal) was cloned and expressed in the S. cerevisiae strain BJ3505. Different constructions were designed to obtain the degree of purification necessary for enzymatic characterization and to improve the productive process of the enzyme. ScAGal has greater specificity for the synthetic substrate p-nitrophenyl-α-D-galactopyranoside than for natural substrates, followed by the natural glycosides, melibiose, raffinose and stachyose; it only acts on locust bean gum after prior treatment with β-mannosidase. Furthermore, this enzyme strongly resists proteases, and shows remarkable activation in their presence. Hydrolysis of galactose bonds linked to terminal non-reducing mannose residues of synthetic galactomannan-oligosaccharides confirms that ScAGal belongs to the first group of α-galactosidases, according to substrate specificity. Optimization of culture conditions by the statistical model of Response Surface helped to improve the productivity by up to tenfold when the concentration of the carbon source and the aeration of the culture medium was increased, and up to 20 times to extend the cultivation time to 216 h.

CONCLUSIONS

ScAGal characteristics and improvement in productivity that have been achieved contribute in making ScAGal a good candidate for application in the elimination of raffinose family oligosaccharides found in many products of the food industry.

Optimization of deacidification for concentrated grape juice

Excessive organic acids in grape juice will not only result in poor taste but will also cause turbidity and sedimentation. Tartaric acid exerts the most significant acidity among all organic acids in grape juice. In this study, we used tartaric acid as the main target and anion-exchange resin to remove tartaric acid from concentrated grape juice. Factors influencing the removal process were optimized by liquid chromatography with ultraviolet detection and statistical analysis for optimal deacidification of concentrated grape juice. Use of the anion-exchange resin 335 treat the concentrated grape juice at a ratio of 1:6 (2:11.98) at 15.57°C for 4.35 hr. The tartaric acid removal rate reached 69.01%; the anion-exchange resin 335 demonstrated the best removal effect.

Statistical media optimization for the production of clinical uricase from Bacillus subtilis strain SP6

In this study, a potent uricase producing organism was isolated by a thorough screening and identified as Bacillus subtilis strain SP6 by using 16s rDNA sequencing. Response surface methodological optimization was employed for the enhanced production of uricase from newly isolated Bacillus subtilis strain SP6. In media optimization studies, Plackett Burman (PB) design was used for the selection of the critical media components; which were further optimized using central composite design (CCD). Lactose, soya peptone, uric acid and FeSO₄.7H₂O were found to be the critical factors influencing the enzyme production. Optimum uricase production with these factors was deduced using central composite design. Significant level of the factors were 12.2 g/L of lactose, 12.79 g/L of soya peptone, 2.55 g/L of uric acid and 0.00325 g/L FeSO₄.7H₂O. Use of statistical optimization upsurges uricase yield from 1.2 U/ml to 15.87 U/ml enhancing the overall production by 13.23 fold; which confirms that the model is effective for process optimization.

Optimization of nutritional components of medium by response surface methodology for enhanced production of lactase

Lactase has excellent applications in dairy industry and commercially this enzyme is produced from bacterial sources but not in high yields. In this work, the production of lactase was improved by designing of nutrient components in fermentation medium by one factor at a time. Lactose and yeast extract were selected as preferable carbon and nitrogen sources for lactase production with tryptophan and MgSO4 showing enhanced production. Statistical analysis proved to be a useful and powerful tool in developing optimum fermentation conditions. The individual and interactive role of lactose, yeast extract, magnesium sulfate, and tryptophan concentration on lactase production was examined by central composite design. Submerged fermentation with Bacillus subtilis strain VUVD001 produced lactase activity of 63.54 U/ml in optimized medium. The activity was threefold higher in comparison to an unoptimized medium. This result confirmed that the designed medium was useful for producing higher yields of lactase.