One-factor-at-a-time (OFAT) optimization of xylanase production from Trichoderma viride-IR05 in solid-state fermentation

Statistical Optimization and Partial Characterization of Xylanases Produced by Streptomyces sp. S1M3I Using Olive Pomace as a Fermentation Substrate

Xylanase production by Streptomyces sp. S1M3I was optimized by response surface methodology (RSM), followed by a partial characterization of these enzymes. Olive pomace was used as a substrate for growing Streptomyces sp. S1M3I in submerged fermentation. Effects of incubation time, pH, temperature, carbon source, nitrogen source, and inoculum size on xylanase production were studied, through the one-factor-at-a-time method. Then, a 33-factorial experimental design with RSM and the Box-Behnken design was investigated for the major influence factors. Maximum xylanase production (11.28 U/mL) was obtained when the strain was grown in mineral medium supplemented with 3% (w/v) of olive pomace powder and 0.3% (w/v) of ammonium sulfate, at a pH 7.4 and an incubation temperature of 40 °C. The xylanases in the supernatant degraded all tested substrates, with higher activity for the low-viscosity wheat arabinoxylan substrate. Two xylanases with close molecular masses were detected by zymogram analysis: Xyl-1 and Xyl-2 with molecular masses of 24.14 kDa and 27 kDa, respectively. The optimization of enzyme production parameters of Streptomyces sp. S1M3I and the characterization of these enzymes are prerequisites to enhancing xylanase production yield, which is crucial for further biotechnological processes.

The Existing Recovery Approaches of the Huangjiu Lees and the Future Prospects: A Mini Review

Huangjiu lees (HL) is a byproduct in Chinese Huangjiu production with various nutrient and biological functional components. Without efficient treatment, it could cause environmental issues and bioresource wasting. Existing dominant recovery approaches focus on large-scale disposal, but they ignore the application of high-value components. This study discusses the advantages and limitations of existing resourcing approaches, such as feed, food and biogas biological production, considering the efficiency and value of HL resourcing. The extraction of functional components as a suggestion for HL cascade utilization is pointed out. This study is expected to promote the application of HL resourcing.

Harnessing Mucor spp. for Xylanase Production: Statistical Optimization in Submerged Fermentation Using Agro-Industrial Wastes

Xylan is the primary hemicellulosic polymer found in lignocellulosic agricultural wastes and can be degraded by xylanase. In the current research, Mucor circinelloides and M. hiemalis were tested for their ability to produce xylanase from tangerine peel by submerged fermentation. Experiments on five variables were designed with Box–Behnken design and response surface methodology. Analysis of variance was exercised, the xylanase output was demonstrated with a mathematical equation as a function of the five factors, and the quixotic states for xylanase biosynthesis was secured. In addition, xylanase was partially purified, characterized, and immobilized on calcium alginate beads. The optimum parameters for xylanase production by M. circinelloides and M. hiemalis were consisted of incubation temperature (30 and 20°C), pH value (9 and 7) incubation period (9 and 9 days), inoculum size (3 and 3 mL), and substrate concentration (3 and 3 g/100 mL), respectively. M. circinelloides and M. hiemalis demonstrated the highest xylanase activities after RSM optimization, with 42.23 and 35.88 U/mL, respectively. The influence of single, interchange, and quadratic factors on xylanase output was investigated using nonlinear regression equations with significant R² and p values. The partial purification of M. circinelloides and M. hiemalis xylanase yielded 1.69- and 1.97-fold purification, and 30.74 and 31.34% recovery with 292.08 and 240.15 U/mg specific activity, respectively. Partially purified xylanase from M. circinelloides and M. hiemalis demonstrated the highest activity at neutral pH and 60 and 50°C, respectively. The immobilized M. circinelloides and M. hiemalis xylanase retained 84.02 and 79.43% activity, respectively. The production of xylanase from M. circinelloides and M. hiemalis utilizing RSM is deemed profitable for the decomposition of the agro-industrial wastes.

Comparison of Liquid and Solid-State Fermentation Processes for the Production of Enzymes and Beta-Glucan from Hulled Barley

Solid-state fermentation using hulled barley was carried out to produce enzymes and β-glucan. The one-factor-at-a-time experiments were carried out to determine the optimal composition of the basal medium. The modified synthetic medium composition in liquid-state fermentation was determined to be 70 g/l hulled barley, 0 g/l rice bran, 5 g/l soytone, and 6 g/l ascorbic acid. Optimal pretreatment conditions of hulled barley by solid-state fermentation were evaluated in terms of maximum production of fungal biomass, amylase, protease, and β-glucan, which were 1.26 mg/g, 31310.34 U/g, 2614.95 U/g, and 14.6% (w/w), respectively, at 60 min of pretreatment condition. Thus, the solid-state fermentation process was found to enhance the overall fermentation yields of hulled barley to produce high amounts of enzymes and β-glucan.

Enhanced production of alkane hydroxylase from Penicillium chrysogenum SNP5 (MTCC13144) through feed-forward neural network and genetic algorithm

Alkane hydroxylase (AlkB), a membrane-bound enzyme has high industrial demand; however, its economical production remains challenging due to its intrinsic nature and co-factor dependency. In the current study, various critical process parameters for optimum production of AlkB have been optimized through feed forward neural network (FFNN) and genetic algorithm (GA) models using Penicillium chrysogenum SNP5 (MTCC13144). AlkB specific activity under preliminary un-optimized conditions i.e., 1% hexadecane, 7.4 pH, 11 days incubation time, 28 °C incubation temperature and 1 ml of inoculum size was 100 U/mg. ‘One variable at a time’ (OVAT) strategy was used to identify optimum physicochemical parameters and then its output data was fed to develop a model of FFNN with ‘6-12-1’ topology. Outputs of FFNN were further optimized through GA to minimize errors and intensify search level. This has provided superior predictive performances with 0.053 U/mg overall mean absolute percentage error (MAPE), 6.801 U/mg root mean square errors (RMSE), and 0.987 overall correlation coefficient (R). The AlkB specific activity improved by 3.5-fold, i.e., from 100 U/mg under preliminary un-optimized conditions to 351.32 U/mg under optimum physicochemical conditions obtained through FFNN-GA hybrid method, i.e., hexadecane (carbon source): 1.56% v/v, FeSO₄: 0.63 mM, incubation temperature: 27.40 °C, pH: 7.38, incubation time: 12.35 days and inoculums size: 1.33 ml. The developed process would be a stepping stone to fulfill the high industrial demands of  Alkane hydroxylase.

Advances in research on solid-state fermented feed and its utilization: The pioneer of private customization for intestinal microorganisms

With sustainable development of biotechnology, increasing attention has been placed on utilization of solid-state fermented feed (SFF). Solid-state fermented feed has been a candidate strategy to alleviate the contradiction between supply and demand of feed resources, ensure food hygiene safety, promoting energy conservation, and emission reduction. In production of SFF, a variety of organic acids, enzymes, vitamins, peptides, and other unknown growth factors are produced, which could affect performance of animals. Solid-state fermented feed produced by different fermentation techniques has great instability on different physiological stages of different animals, which hinders the application and standardized production of SFF. Herein, we summarize the current advances in the role of the characteristics of SFF prepared by different manufacturing technique and its research progress in animal experiments on growth performance, gastrointestinal ecology, and immune system, so as to provide references for further acquiring a relatively perfect set of SFF production and evaluation systems.

Thermostable trypsin-like protease by Penicillium roqueforti secreted in cocoa shell fermentation: Production optimization, characterization, and application in milk clotting

The increased demand for cheese and the limited availability of calf rennet justifies the search for milk-clotting enzymes from alternative sources. Trypsin-like protease by Penicillium roqueforti was produced by solid-state fermentation using cocoa shell waste as substrate. The production of a crude enzyme extract that is rich in this enzyme was optimized using a Doehlert-type multivariate experimental design. The biochemical characterization showed that the enzyme has excellent activity and stability at alkaline pH (10-12) and an optimum temperature of 80°C, being stable at temperatures above 60°C. Enzymatic activity was maximized in the presence of Na⁺ (192%), Co²⁺ (187%), methanol (153%), ethanol (141%), and hexane (128%). Considering the biochemical characteristics obtained and the milk coagulation activity, trypsin-like protease can be applied in the food industry, such as in milk clotting and in the fabrication of cheeses.

Coproduction of Enzymes and Beta-Glucan by Aspergillus oryzae Using Solid-State Fermentation of Brown Rice

The effect of medium composition on enzyme and β-glucan production by Aspergillus oryzae KCCM 12698 was investigated. Brown rice, rice bran, nitrogen, and ascorbic acid are key components of the synthetic medium used in liquid-state fermentation. To determine the optimal concentrations of these components for enzyme and β-glucan production, we conducted one factor at a time experiments, which showed that the optimal concentrations were 30 g/l brown rice, 30 g/l rice bran, 10 g/l soytone, and 3 g/l ascorbic acid. Pretreatment of brown rice for 60 min prior to inoculation enhanced fungal biomass, while increasing the production of enzymes and β-glucan using solidstate fermentation. Maximum fungal biomass of 0.76 mg/g, amylase (26,551.03 U/g), protease (1,340.50 U/g), and β-glucan at 9.34% (w/w) were obtained during fermentation. Therefore, solidstate fermentation of brown rice is a process that could enhance yield and overall production of enzymes and β-glucan for use in various applications.

Cellulosic and hemicellulosic fractions of sugarcane bagasse: Potential, challenges and future perspective

Sugarcane bagasse is a rich source of cellulose (32-45%), hemicellulose (20-32%) and lignin (17-32%), 1.0-9.0% ash and some extractives. Huge amount of the generation of sugarcane bagasse has been a great challenge to industries and environment at global level for many years. Though cellulosic and hemicellulosic fractions in bagasse makes it a potential raw substrate for the production of value-added products at large scale, the presence of lignin hampers its saccharification which further leads to low yields of the value-added products. Therefore, an appropriate pretreatment strategy is of utmost importance that effectively solubilizes the lignin that exposes cellulose and hemicellulose for enzymatic action. Pretreatment also reduces the biomass recalcitrance i.e., cellulose crystallinity, structural complexity of cell wall and lignification for its effective utilization in biorefinery. Sugarcane bagasse served as nutrient medium for the cultivation of diverse microorganisms for the production of industrially important metabolites including enzymes, reducing sugars, prebiotic, organic acids and biofuels. Sugarcane bagasse has been utilized in the generation of electricity, syngas and as biosorbant in the bioremediation of heavy metals. Furthermore, the ash generated from bagasse is an excellent source for the synthesis of high strength and light weight bricks and tiles. Present review describes the utility of sugarcane bagasse as sustainable and renewable lignocellulosic substrate for the production of industrially important multifarious value-added products.

Evaluation of 2,3-Butanediol Production from Red Seaweed Gelidium amansii Hydrolysates Using Engineered Saccharomyces cerevisiae

Hyper-thermal (HT) acid hydrolysis of red seaweed Gelidium amansii was performed using 12% (w/v) slurry and an acid mix concentration of 180 mM at 150°C for 10 min. Enzymatic saccharification when using a combination of Celluclast 1.5 L and CTec2 at a dose of 16 U/ml led to the production of 12.0 g/l of reducing sugar with an efficiency of enzymatic saccharification of 13.2%. After the enzymatic saccharification, 2,3-butanediol (2,3-BD) fermentation was carried out using an engineered S. cerevisiae strain. The use of HT acid-hydrolyzed medium with 1.9 g/l of 5-hydroxymethylfurfural showed a reduction in the lag time from 48 to 24 h. The 2,3-BD concentration and yield coefficient at 72 h were 14.8 g/l and 0.30, respectively. Therefore, HT acid hydrolysis and the use of the engineered S. cerevisiae strain can enhance the overall 2,3-BD yields from G. amansii seaweed.

Aspergillus nidulans: A Potential Resource of the Production of the Native and Heterologous Enzymes for Industrial Applications

Aspergillus nidulans is a filamentous fungus that is a potential resource for industrial enzymes. It is a versatile fungal cell factory that can synthesize various industrial enzymes such as cellulases, β-glucosidases, hemicellulases, laccases, lipases, proteases, β-galactosidases, tannases, keratinase, cutinases, and aryl alcohol oxidase. A. nidulans has shown the potential to utilize low-cost substrates such as wheat bran, rice straw, sugarcane bagasse, rice bran, coir pith, black gram residue, and chicken feathers to produce enzymes cost-effectively. A. nidulans has also been known as a model organism for the production of heterologous enzymes. Several studies reported genetically engineered strains of A. nidulans for the production of different enzymes. Native as well as heterologous enzymes of A. nidulans have been employed for various industrial processes.

Enhanced production of bacterial xylanase and its utility in saccharification of sugarcane bagasse

An investigation was carried out using sugarcane bagasse as the agricultural residue to study the optimization of xylanase production by solid-state fermentation. Maximum xylanase production (20.35 U/g substrate) was achieved by Bacillus substilis subsp. subtilis JJBS250 using 'one variable at a time approach' at pH 7.0, 40 °C after 48 h. After statistical optimization by response surface methodology (RSM) there was 4.82-fold improvement in xylanase production (98.16 U/g substrate). Further optimization of untreated and sodium carbonate pretreated sugarcane bagasse enzymatic hydrolysis was carried out using both bacterial (Bacillus substilis subsp. subtilis JJBS250) and fungal (Myceliophthora thermophila BJTLRMDU3) xylanases that showed high amount of reducing sugar liberation from untreated sugarcane bagasse (124.24 mg/g substrate) as compared to pretreated (76.23 mg/g substrate) biomass. Furthermore, biophysical characterization of untreated and sodium carbonate pretreated sugarcane bagasse using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), revealed the structural changes in the pretreated biomass.

Spent Coffee Waste as a Potential Media Component for Xylanase Production and Potential Application in Juice Enrichment

In this study, spent coffee waste (SCW) was used as the sole carbon source for xylanase production in solid state fermentation mode using Aspergillus niger. A Box-Behnken design was constructed using three parameters viz. temperature, initial moisture content, and log number of spores to determine the optimal fermentation condition. The best fermentation conditions for xylanase production were found to be incubation at 30 °C with an initial moisture content of 70% and using an inoculum of 6.5 × 10⁶ spores/g of dry SCW. Furthermore, the design of experiments revealed that maintaining a medium composition of 0.2 g of yeast extract, 0.04 g of K₂HPO₄, and 0.03 g of MgSO₄ increased xylanase production. Under optimised solid-state fermentation conditions an enzyme activity of 6495.6 IU/g of dry SCW was recorded, which was approximately 1.39-fold higher than that of control (4649 IU/g of dry SCW). The efficacy of the purified xylanase as a juice enrichment agent for strawberry, blueberry, and raspberry pulp was tested.

Production, characteristics, and biotechnological applications of microbial xylanases

Microbial xylanases have gathered great attention due to their biotechnological potential at industrial scale for many processes. A variety of lignocellulosic materials, such as sugarcane bagasse, rice straw, rice bran, wheat straw, wheat bran, corn cob, and ragi bran, are used for xylanase production which also solved the great issue of solid waste management. Both solid-state and submerged fermentation have been used for xylanase production controlled by various physical and nutritional parameters. Majority of xylanases have optimum pH in the range of 4.0-9.0 with optimum temperature at 30-60 °C. For biochemical, molecular studies and also for successful application in industries, purification and characterization of xylanase have been carried out using various appropriate techniques. Cloning and genetic engineering are used for commercial-level production of xylanase, to meet specific economic viability and industrial needs. Microbial xylanases are used in various biotechnological applications like biofuel production, pulp and paper industry, baking and brewing industry, food and feed industry, and deinking of waste paper. This review describes production, characteristics, and biotechnological applications of microbial xylanases.

A detailed overview of xylanases: an emerging biomolecule for current and future prospective

Xylan is the second most abundant naturally occurring renewable polysaccharide available on earth. It is a complex heteropolysaccharide consisting of different monosaccharides such as l-arabinose, d-galactose, d-mannoses and organic acids such as acetic acid, ferulic acid, glucuronic acid interwoven together with help of glycosidic and ester bonds. The breakdown of xylan is restricted due to its heterogeneous nature and it can be overcome by xylanases which are capable of cleaving the heterogeneous β-1,4-glycoside linkage. Xylanases are abundantly present in nature (e.g., molluscs, insects and microorganisms) and several microorganisms such as bacteria, fungi, yeast, and algae are used extensively for its production. Microbial xylanases show varying substrate specificities and biochemical properties which makes it suitable for various applications in industrial and biotechnological sectors. The suitability of xylanases for its application in food and feed, paper and pulp, textile, pharmaceuticals, and lignocellulosic biorefinery has led to an increase in demand of xylanases globally. The present review gives an insight of using microbial xylanases as an “Emerging Green Tool” along with its current status and future prospective.

Production of xylanases by Bacillus sp. TC-DT13 in solid state fermentation using bran wheat

Xylanases have gained increasing importance due to their diverse applications in the food, paper, and pharmaceutical industries, however, the production of these enzymes currently uses expensive substrates. It has already been estimated that more than 30% of the enzyme production cost originates from the substrate. The present study aimed to optimize the production of extracellular xylanases by the Bacillus sp. TC-DT 13 using solid-state fermentation with agro-industrial residues, with a view at reducing the production cost of these enzymes. All the agro-industrial residues were tested in submerged fermentation to select the best inductor to produce xylanase. Among these residues, wheat bran was selected as the best inducer of xylanase production with 1500 U/mL. Regarding solid-state fermentation, the use of wheat bran as the only fermentation substrate was used and a ratio of 1:4 moisture over a time of 144 hours induced higher amount of xylanase reaching 2943 U/g. The use of carbon and nitrogen sources did not result in the increase in production of xylanolitic enzymes. The use of agro-industrial residues in the solid-state fermentation, besides increasing the production of xylanase, reduces the cost of production and is an environmentally friendly alternative.

Characterization of Dark Septate Endophytic Fungi and Improve the Performance of Liquorice Under Organic Residue Treatment

Dark septate endophytic (DSE) fungi is a diverse group of Ascomycetes fungi that colonize the plants roots, and may facilitate plant growth and fitness, however, their ecological roles need further clarification. This study aimed to evaluate the growth promoting effects of DSE fungi in a medicinal plant, liquorice (Glycyrrhiza uralensis), under additional organic residues. First, we isolated, identified and characterized, two DSE fungal species (Acrocalymma vagum and Paraboeremia putaminum) harboring inside the roots of liquorice growing in arid areas of China. Second, we examined the performance and rhizosphere soil parameters of liquorice plants inoculated with these fungi under additional sterilized organic residues and unsterilized organic residue (containing Trichoderma viride population) in a growth chamber. The results showed that two DSE strains could effectively colonize plant roots and formed a strain-dependent symbiosis with liquorice. DSE inoculation alone increased the plant biomass, and glycyrrhizic acid and glycyrrhizin content. It also improved the root system and N and P absorption by plants, consequently depleting these macronutrients in the soil. Residues alone increased soil organic matter, available phosphorus (P), and available nitrogen (N) content, and plant biomass, N, P, glycyrrhizic acid, and glycyrrhizin content. Mantel test and structural equation model (SEM) analysis demonstrated that DSE associated with residues significantly positively influenced soil organic matter, available P and available N, and plant biomass, glycyrrhizin, N, P, and root surface area. Variation in plant growth and glycyrrhizic acid and glycyrrhizin accumulation can be attributed to the effects of DSE inoculation. DSE associated with residues exhibited a general synergistic effect on the growth and accumulation of glycyrrhizic acid and glycyrrhizin of liquorice. We demonstrate for the first time, two DSE fungi in the liquorice roots that have potential use as promoter for the cultivation of medicinal plant.

Enhanced endoxylanase production by Myceliophthora thermophila with applicability in saccharification of agricultural substrates

The production of enzymes by solid-state fermentation is an interesting process and currently used worldwide as it can be carried out in solid matrix in absence of free water. In present study, Myceliophthora thermophila BJTLRMDU3 produced high titres of endoxylanase (890.55 U/g DR, dry residue) using 5 g rice straw at pH 7.0 and at 45 °C with 1:7 (w/v) solid-to-moisture ratio with inoculum rate of 12 × 10⁶ spores/ml after 4 days in solid-state fermentation. High enzyme titre was produced after moistening the rice straw with solution containing ammonium sulphate (0.4%), K₂HPO₄ (1.0%), MgSO₄·7H₂O (0.3%), FeSO₄·7H₂O (0.03%) and CaCl₂ (0.03%). Addition of sucrose (2% w/v) and ammonium nitrate (2% w/v) further enhanced the endoxylanase production. A high endoxylanase production was achieved at water activity (a _W) of 0.95 (1639.80 U/g DR) that declined drastically below this value. Among different surfactants, Tween 20 (3% v/v) enhanced the secretion of endoxylanase (2047.91 U/g DR). Furthermore, on optimization of K₂HPO₄ concentration, it was found that 0.5% K₂HPO₄ improved (2191.28 U/g DR) endoxylanase production and overall 4.35-folds increase in production of endoxylanase was achieved after optimization of culture conditions. The enzyme has potential to liberate monomeric (xylose) as well as oligomeric (xylotiose, xylotetrose, and xylopantose) sugars from xylan. On saccharification of rice straw and corncob with endoxylanase, maximum yield of reducing sugars was 135.61 and 132.61 mg/g of substrate recorded after 48, and 36 h, respectively.

Butanol and butyric acid production from Saccharina japonica by Clostridium acetobutylicum and Clostridium tyrobutyricum with adaptive evolution

Optimal conditions of hyper thermal (HT) acid hydrolysis of the Saccharina japonica was determined to a seaweed slurry content of 12% (w/v) and 144 mM H2SO4 at 160 °C for 10 min. Enzymatic saccharification was carried out at 50 °C and 150 rpm for 48 h using the three enzymes at concentrations of 16 U/mL. Celluclast 1.5 L showed the lowest half-velocity constant (Km) of 0.168 g/L, indicating a higher affinity for S. japonica hydrolysate. Pretreatment yielded a maximum monosaccharide concentration of 36.2 g/L and 45.7% conversion from total fermentable monosaccharides of 79.2 g/L with 120 g dry weight/L S. japonica slurry. High cell densities of Clostridium acetobutylicum and Clostridium tyrobutyricum were obtained using the retarding agents KH2PO4 (50 mM) and NaHCO3 (200 mM). Adaptive evolution facilitated the efficient use of mixed monosaccharides. Therefore, adaptive evolution and retarding agents can enhance the overall butanol and butyric acid yields from S. japonica.

Fermentation: A Boon for Production of Bioactive Compounds by Processing of Food Industries Wastes (By-Products)

A large number of by-products or wastes are produced worldwide through various food industries. These wastes cause a serious disposable problem with the environment. So, now a day's different approaches are used for alternative use of these wastes because these by-products are an excellent source of various bioactive components such as polyphenols, flavonoids, caffeine, carotenoids, creatine, and polysaccharides etc. which are beneficial for human health. Furthermore, the composition of these wastes depends on the source or type of waste. Approximately half of the waste is lignocellulosic in nature produced from food processing industries. The dissimilar types of waste produced by food industries can be fortified by various processes. Fermentation is one of the oldest approaches and there are three types of fermentation processes that are carried out such as solid state, submerged and liquid fermentation used for product transformation into value added products through microorganisms. Selections of the fermentation process are product specific. Moreover, various studies were performed to obtain or fortified different bioactive compounds that are present in food industries by-products or wastes. Therefore, the current review article discussed various sources, composition and nutritive value (especially bioactive compounds) of these wastes and their management or augmentation of value-added products through fermentation.

One-step process for producing prebiotic arabino-xylooligosaccharides from brewer's spent grain employing Trichoderma species

Xylooligosaccharides (XOS) are prebiotic nutraceuticals that can be sourced from lignocellulosic biomass, such as agro-residues. This study reports for the first time an optimization study of XOS production from agro-residues by direct fermentation using two Trichoderma species. A total of 13 residues were evaluated as potential substrates for single-step production. The best results were found for Trichoderma reesei using brewers' spent grain (BSG) as substrate. Under optimal conditions (3 days, pH 7.0, 30 °C and 20 g/L of BSG), a production yield of 38.3 ± 1.8 mg/g (xylose equivalents/g of BSG) was achieved. The obtained oligosaccharides were identified as arabino-xylooligosacharides (AXOS) with degree of polymerization from 2 to 5. One-step fermentation proved to be a promising strategy for AXOS production from BSG, presenting a performance comparable with the use of commercial enzymes. This study provides new insights towards the bioprocess integration, enabling further developments of low-cost bioprocesses for the production of these valuable compounds.

Production of α-1,4-glucosidase from Bacillus licheniformis KIBGE-IB4 by utilizing sweet potato peel

In the current study, sweet potato peel (Ipomoea batatas) was observed as the most favorable substrate for the maximum synthesis of α-1,4-glucosidase among various agro-industrial residues. Bacillus licheniformis KIBGE-IB4 produced 6533.0 U ml^-1 of α-1,4-glucosidase when growth medium was supplemented with 1% dried and crushed sweet potato peel. It was evident from the results that bacterial isolate secreted 6539.0 U ml^-1 of α-1,4-glucosidase in the presence of 0.4% peptone and meat extract with 0.1% yeast extract. B. licheniformis KIBGE-IB4 released 6739.0 and 7190.0 U ml^-1 of enzyme at 40 °C and pH 7.0, respectively. An improved and cost-effective growth medium design resulted 8590.0 U ml^-1 of α-1,4-glucosidase with 1.3-fold increase as compared to initial amount from B. licheniformis KIBGE-IB4. This enzyme can be used to fulfill the accelerating demand of food and pharmaceutical industries. Further purification and immobilization of this enzyme can also enhance its utility for various commercial applications. Graphical abstract Pictorial representation of maltase production from sweet potato peel.

Potential application of waste from castor bean (Ricinus communis L.) for production for xylanase of interest in the industry

Xylanases activity (XY) from Aspergillus japonicus URM5620 produced by Solid-State Fermentation (SSF) of castor press cake (Ricinus communis) on different conditions of production and extraction by PEG/citrate aqueous two-phase system (ATPS) were investigated. XY production was influenced by substrate amount (5–10 g), initial moisture (15–35 %), pH (4.0–6.0) and temperature (25–35 °C), obtaining the maximum activity of 29,085 ± 1808 U g ds⁻¹ using 5.0 g of substrate with initial moisture of 15 % at 25 °C and pH 6.0, after 120 h of fermentation. The influence of PEG molar mass (1000–8000 g mol⁻¹), phase concentrations (PEG 20.0–24.0 % w/w and sodium citrate 15–20 % w/w) and pH (6.0–8.0) on partition coefficient, purification factor, yield and selectivity of XY were determinate. Enzyme partitioning into the PEG rich phase was favored by M_PEG 8000 (g mol⁻¹), C_PEG 24 % (w/w), C_C 20 % (w/w) and pH 8.0, resulting in partition coefficient of 50.78, activity yield of 268 %, 7.20-fold purification factor and selectivity of 293. A. japonicus URM5620 has a potential role in the development of a bioprocess for the XY production using low-cost media. In addition, the present study proved it is feasible to extract xylanase from SSF by adopting the one step ATPS consisting of PEG/citrate.

Evaluation of hyper thermal acid hydrolysis of Kappaphycus alvarezii for enhanced bioethanol production

Hyper thermal (HT) acid hydrolysis of Kappaphycus alvarezii, a red seaweed, was optimized to 12% (w/v) seaweed slurry content, 180mM H2SO4 at 140°C for 5min. The maximum monosaccharide concentration of 38.3g/L and 66.7% conversion from total fermentable monosaccharides of 57.6g/L with 120gdw/L K. alvarezii slurry were obtained from HT acid hydrolysis and enzymatic saccharification. HT acid hydrolysis at a severity factor of 0.78 efficiently converted the carbohydrates of seaweed to monosaccharides and produced a low concentration of inhibitory compounds. The levels of ethanol production by separate hydrolysis and fermentation with non-adapted and adapted Kluyveromyces marxianus to high concentration of galactose were 6.1g/L with ethanol yield (YEtOH) of 0.19 at 84h and 16.0g/L with YEtOH of 0.42 at 72h, respectively. Development of the HT acid hydrolysis process and adapted yeast could enhance the overall ethanol fermentation yields of K. alvarezii seaweed.