COST-EFFECTIVE ENDO-MANNANASE FROMBacillussp. CFR1601 AND ITS APPLICATION IN GENERATION OF OLIGOSACCHARIDES FROM GUAR GUM AND AS DETERGENT ADDITIVE

Unravelling biochemical and structural features of Bacillus licheniformis GH5 mannanase using site-directed mutagenesis and high-resolution protein crystallography studies

Glycoside hydrolase family 5 (GH5) encompasses enzymes with several different activities, including endo-1,4-β-mannosidases. These enzymes are involved in mannan degradation, and have a number of biotechnological applications, such as mannooligosaccharide prebiotics production, stain removal and dyes decolorization, to name a few. Despite the importance of GH5 enzymes, only a few members of subfamily 7 were structurally characterized. In the present work, biochemical and structural characterization of Bacillus licheniformis GH5 mannanase, BlMan5_7 were performed and the enzyme cleavage pattern was analyzed, showing that BlMan5_7 requires at least 5 occupied subsites to perform efficient hydrolysis. Additionally, crystallographic structure at 1.3 Å resolution was determined and mannoheptaose (M7) was docked into the active site to investigate the interactions between substrate and enzyme through molecular dynamic (MD) simulations, revealing the existence of a - 4 subsite, which might explain the generation of mannotetraose (M4) as an enzyme product. Biotechnological application of the enzyme in stain removal was investigated, demonstrating that BlMan5_7 addition to washing solution greatly improves mannan-based stain elimination.

Functional β-mannooligosaccharides: Sources, enzymatic production and application as prebiotics

One of the emerging non-digestible oligosaccharide prebiotics is β-mannooligosaccharides (β-MOS). β-MOS are β-mannan derived oligosaccharides, they are selectively fermented by gut microbiota, promoting the growth of beneficial microorganisms (probiotics), whereas the growth of enteric pathogens remains unaffected or gets inhibited in their presence, along with production of metabolites such as short-chain fatty acids. β-MOS also exhibit several other bioactive properties and health-promoting effects. Production of β-MOS using the enzymes such as β-mannanases is the most effective and eco-friendly approach. For the application of β-MOS on a large scale, their production needs to be standardized using low-cost substrates, efficient enzymes and optimization of the production conditions. Moreover, for their application, detailed in-vivo and clinical studies are required. For this, a thorough information of various studies in this regard is needed. The current review provides a comprehensive account of the enzymatic production of β-MOS along with an evaluation of their prebiotic and other bioactive properties. Their characterization, structural-functional relationship and in-vivo studies have also been summarized. Research gaps and future prospects have also been discussed, which will help in conducting further research for the commercialization of β-MOS as prebiotics, functional food ingredients and therapeutic agents.

The structures of two glucomannans from Bletilla formosana and their protective effect on inflammation via inhibiting NF-κB pathway

Bletilla formosana is a traditional Chinese herbal medicine and is widely consumed as foods and medicines in China. However, the chemical structure and bioactivity of its polysaccharides remain unknown. Herein, two new polysaccharides, BFP60 and BFP80, with molecular weights of 3.99 kDa and 10.07 kDa, respectively, were isolated and purified from dried tuber of B. formosana. Structural analysis suggested that BFP60 and BFP80 may have backbone consisted of →4)-β-d-Man-(1→,→4)-β-d-Glc-(1→,→4)-2-O-acetyl-β-d-Man-(1→, and →4)-3-O-acetyl-β-d-Man-(1→. Inflammation assay in LPS-induced RAW264.7 cells showed that the productions of NO and pro-inflammatory cytokines including IL-6, IL-1β, TNF-α, and IFN-γ were significantly reduced, and the expression of iNOS, COX-2, and target proteins in the NF-κB pathway were suppressed after BFP60 and BFP80 pretreatment. These findings indicated that this novel polysaccharide had significant inflammatory protective effects in vitro.

Reshaping the binding channel of a novel GH113 family β-mannanase from Paenibacillus cineris (PcMan113) for enhanced activity

Endo-β-mannanases are important enzymes for degrading lignocellulosic biomass to generate mannan, which has significant health effects as a prebiotic that promotes the development of gut microbiota. Here, a novel endo-β-mannanase belonging to glycoside hydrolase (GH) family 113 from Paenibacillus cineris (PcMan113) was cloned, expressed and characterized, as one of only a few reported GH113 family β-mannanases. Compared to other functionally and structurally characterized GH113 mannanases, recombinant PcMan113 showed a broader substrate spectrum and a better performance. Based on a structural homology model, the highly active mutant PcMT3 (F110E/N246Y) was obtained, with 4.60- and 5.53-fold increases of enzyme activity (towards KG) and catalytic efficiency (kcat/Km, against M5) compared with the WT enzyme, respectively. Furthermore, molecular dynamics (MD) simulations were conducted to precisely explore the differences of catalytic activity between WT and PcMT3, which revealed that PcMT3 has a less flexible conformation, as well as an enlarged substrate-binding channel with decreased steric hindrance and increased binding energy in substrate recognition. In conclusion, we obtained a highly active variant of PcMan113 with potential for commercial application in the manufacture of manno-oligosaccharides.

High surfactant-tolerant β-mannanase isolated from Dynastes hercules larvae excrement, and identification of its hotspot using site-directed mutagenesis and molecular dynamics simulations

The β-mannanase from Bacillus subtilis HM7 (Man26HM7) isolated from Dynastes hercules larvae excrement was cloned and expressed in Escherichia coli. Biochemical characterization shows that optimal pH and temperature for catalysis are 6.0 and 50 °C, respectively. Man26HM7 displayed excellent surfactant stability by retaining 70% of initial activity in 1%(w/v) SDS, and more than 90% of initial activity in 1%(w/v) Triton X-100 and Tween 80. Results from amino acid sequence alignment and molecular modeling suggest residue 238 of β-mannanase as a hotspot of SDS-tolerance. Mutagenesis at the equivalent residue of another homolog, β-mannanase from Bacillus subtilis CAe24 (Man26CAe24), significantly enhanced the SDS stability of this enzyme. Comparative computational analysis, including molecular docking and molecular dynamics simulation, were then performed to compute the binding free energy of SDS to Man26HM7, Man26CAe24, and variant enzymes. The results suggest that residue 238 of Man26HM7 is involved in SDS binding to the hydrophobic surface of β-mannanase. This study provides not only the promising application of Man26HM7 in detergent and cleaning products but also valuable information for enhancing the surfactant stability of β-mannanase by enzyme engineering.

Purification of a Thermostable β-mannanase from Paenibacillus Thiaminolyticus - characterization and its Potential Use as a Detergent Additive

Endo-1, 4- β- D-mannanase (EC 3.2.1.78) is a glycoside hydrolase involved in random cleavage of β-1, 4- D-manno-pyranosyl linkages within mannans and heteromannans and generates branched and linear oligosaccharides. A β-mannanase was purified from a thermotolerant bacterium Paenibacillus thiaminolyticus isolated from a soil sample. Enzyme was purified to homogeneity with specific activity of 8812 U/mg protein. Sodium dodecyl sulfate (SDS) and native poly-acryl amide gel electrophoresis indicated that the purified mannanase is a monomeric protein with a molecular mass of 38 kDa. The purified enzyme was found to be maximally active at temperature and pH of 60°C and 7.0, respectively. It was stable at 55°C for 24 h and maintained more than 50 % activity up to 3 h at 60°C. The enzyme was very stable in the pH range of 5.0-9.0. Purified β-mannanase demonstrated high stability after 1 h of pre-incubation with most of the tested organic solvents. Enzyme retained significant stability in the presence of various detergent additives, commercially available detergents and dish washing liquids. The high compatibility and substantial stability in the presence of nonionic detergents and dishwashing liquids confirmed its utility as an additive to dish washing liquids and laundry detergents. Enzyme exhibited efficacious de-staining of heteromannan based stains of chocolate ice cream and salad dressing in the wash performance test for detergent application. It also exhibited anti-soil redeposition effect on cotton swatches treated with tennis court clay and heteromannans.

Production of manno-oligosaccharide from Gleditsia microphylla galactomannan using acetic acid and ferrous chloride

A novel and efficient method for manno-oligosaccharides (MOS) production has been proposed by utilizing Gleditsia microphylla galactomannan as the starting material. This co-operative hydrolysis using ferrous chloride (Fe²⁺) and acetic acid (HAc) effectively improved the MOS yield and meanwhile decreased the amount of monosaccharide and the 5-hydroxymethyl-furfural (HMF). The highest yields under the optimum conditions were 46.7% by HAc hydrolysis (5 M HAc at 130 °C for 120 min); 37.3% by Fe²⁺ hydrolysis (0.1 M Fe²⁺ at 150 °C for 120 min); and 51.4% by co-operative hydrolysis (2 M HAc, 0.05 M Fe²⁺ at 160 °C for 10 min). From the changes in the value of M/G (mannose/galactose) ratios, it was deduced that Fe²⁺ predominantly cleaves the main chain, and HAc assists in the breakage of the side chain, thus resulting in the high-efficient co-operative hydrolysis for the production of MOS.

Applications of Microbial β-Mannanases

Mannans are main components of hemicellulosic fraction of softwoods and they are present widely in plant tissues. β-mannanases are the major mannan-degrading enzymes and are produced by different plants, animals, actinomycetes, fungi, and bacteria. These enzymes can function under conditions of wide range of pH and temperature. Applications of β-mannanases have therefore, been found in different industries such as animal feed, food, biorefinery, textile, detergent, and paper and pulp. This review summarizes the most recent studies reported on potential applications of β-mannanases and bioengineering of β-mannanases to modify and optimize their key catalytic properties to cater to growing demands of commercial sectors.

Enhancement of β-Mannanase Production by Bacillus subtilis ATCC11774 through Optimization of Medium Composition

Palm kernel cake (PKC) has been largely produced in Malaysia as one of the cheap and abundant agro-waste by-products from the palm oil industry and it contains high fiber (mannan) content. The present study aimed to produce β-mannanase by Bacillus subtilis ATCC11774 via optimization of the medium composition using palm kernel cake as substrate in semi-solid fermentation. The fermentation nutrients such as PKC, peptone, yeast extract, sodium chloride, magnesium sulphate (MgSO₂), initial culture pH and temperature were screened using a Plackett-Burman design. The three most significant factors identified, PKC, peptone and NaCl, were further optimized using central composite design (CCD), a response surface methodology (RSM) approach, where yeast extract and MgSO₂ were fixed as a constant factor. The maximum β-mannanase activity predicted by CCD under the optimum medium composition of 16.50 g/L PKC, 19.59 g/L peptone, 3.00 g/L yeast extract, 2.72 g/L NaCl and 0.2 g/L MgSO₂ was 799 U/mL. The validated β-mannanase activity was 805.12 U/mL, which was close to the predicted β-mannanas activity. As a comparison, commercial media such as nutrient broth, M9 and Luria bertani were used for the production of β-mannanase with activities achieved at 204.16 ± 9.21 U/mL, 50.32 U/mL and 88.90 U/mL, respectively. The optimized PKC fermentation medium was four times higher than nutrient broth. Hence, it could be a potential fermentation substrate for the production of β-mannanase activity by Bacillus subtilis ATCC11774.

Optimization of β-mannanase production by Bacillus subtilis US191 using economical agricultural substrates

The Bacillus subtilis US191 strain producing highly thermostable β-mannanase was previously selected as potential probiotic candidate for application as feed supplement in poultry industry. Initially, the level of extracellular β-mannanase production by this strain was 1.48 U ml^-1 . To improve this enzyme titer, the present study was undertaken to optimize the fermentation conditions through experimental designs and valorization of agro-industrial byproducts. Using the Plackett-Burman design, in submerged fermentation, a set of 14 culture variables was evaluated in terms of their effects on β-mannanase production. Locust bean gum (LBG), soymeal, temperature, and inoculum size were subsequently optimized by response surface methodology using Box-Behnken design. Under optimized conditions (1 g L^-1 LBG, 8 g L^-1 soymeal, temperature of 30°C and inoculum size of 10¹⁰  CFU ml^-1 ), a 2.59-fold enhancement in β-mannanase titer was achieved. Next, to decrease the enzyme production cost, the effect of partial substitution of LBG (1 g L^-1 ) by agro-industrial byproducts was investigated, and a Taguchi design was applied. This allowed the attaining of a β-mannanase production level of 8.75 U ml^-1 in presence of 0.25 g L^-1 LBG, 5 g L^-1 of coffee residue powder, 5 g L^-1 of date seeds powder, and 5 g L^-1 of prickly pear seeds powder as mannans sources. Overall, a 5.91-fold improvement in β-mannanase production by B. subtilis US191 was achieved.

High-level expression of a thermophilic and acidophilic β-mannanase from Aspergillus kawachii IFO 4308 with significant potential in mannooligosaccharide preparation

An engineered thermophilic and acidophilic β-mannanase (ManAK) from Aspergillus kawachii IFO 4308 was highly expressed in Pichia pastoris. Through high cell density fermentation, the maximum yield reached 11,600 U/mL and 15.5 g/L, which is higher than most extreme β-mannanases. The recombinant ManAK was thermostable with a temperature optimum of 80 °C, and acid tolerant with a pH optimum of 2.0. ManAK could efficiently degrade locust bean gum, konjac gum, and guar gum into small molecular mannooligosaccharide (<2000 Da), even at high initial substrate concentration (10%), and displayed different Mw distributions in their end products. Docking analysis demonstrated that the catalytic pocket of ManAK could only accommodate a galactopyranosyl residue in subsite -1, which might be responsible for the distinct hydrolysis product compositions from locust bean gum and guar gum. These superior properties of ManAK strongly facilitate mannooligosaccharide preparation and application in food and feed area.

Small-angle X-ray scattering based structure, modeling and molecular dynamics analyses of a family 5 glycoside hydrolase first endo-mannanase named as RfGH5_7 from Ruminococcus flavefaciens

Endo-β-1,4-mannanase named as RfGH5_7 from Ruminococcus flavefaciens cloned, expressed and purified earlier was structurally characterized in present study. The RaptorX modeled structure of RfGH5_7 showed a (β/α)₈ Triose-phosphate Isomerase (TIM) barrel fold. The Ramachandran plot assessment of RfGH5_7 showed that all amino acids fall in allowed region except one, Asn22 in the disallowed region. The superposition of RfGH5_7 modeled structure with its nearest homologues revealed that Glu154 acts as proton donor while Glu249 acts as nucleophile. Secondary structure of RfGH5_7 through Circular Dichroism (CD) analysis revealed 33.5% α-helices, 17% β-strands and 49.5% random coils. Molecular Dynamic (MD) simulation showed Root Mean Square Deviation (RMSD), 0.67 nm and radius of gyration (Rg) between 1.9 nm and 1.85 nm. The binding interaction of mannotetraose on the surface of RfGH5_7 structure displayed polar interactions with His219, Tyr221, Trp278, Ser279 and Gly282 residues. Small-angle X-ray scattering (SAXS) analysis displayed the intact and monodispersed nature of the enzyme RfGH5_7. The radius of gyration (Rg) by Guinier analysis for globular shape was found to be 2.29 ± 0.09 nm and for rod-shape it was 0.95 ± 0.02 nm. Kratky plot confirmed that RfGH5_7 structure is compact and folded in solution. The ab initio derived dummy model of RfGH5_7 displayed single domain structure of yellow humped fish like shape. The RfGH5_7 modeled structure was well fitted with ab initio derived model from SAXS data. Communicated by Ramaswamy H. Sarma.

Validation of leaf enzymes in the detergent and textile industries: launching of a new platform technology

Chemical catalysts are being replaced by biocatalysts in almost all industrial applications due to environmental concerns, thereby increasing their demand. Enzymes used in current industries are produced in microbial systems or plant seeds. We report here five newly launched leaf-enzyme products and their validation with 15 commercial microbial-enzyme products, for detergent or textile industries. Enzymes expressed in chloroplasts are functional at broad pH/temperature ranges as crude-leaf extracts, while most purified commercial enzymes showed significant loss at alkaline pH or higher temperature, required for broad range commercial applications. In contrast to commercial liquid enzymes requiring cold storage/transportation, chloroplast enzymes as a leaf powder can be stored up to 16 months at ambient temperature without loss of enzyme activity. Chloroplast-derived enzymes are stable in crude-leaf extracts without addition of protease inhibitors. Leaf lipase/mannanase crude extracts removed chocolate or mustard oil stains effectively at both low and high temperatures. Moreover, leaf lipase or mannanase crude-extracts removed stain more efficiently at 70 °C than commercial microbial enzymes (<10% activity). Endoglucanase and exoglucanase in crude leaf extracts removed dye efficiently from denim surface and depilled knitted fabric by removal of horizontal fibre strands. Due to an increased demand for enzymes in the food industry, marker-free lettuce plants expressing lipase or cellobiohydrolase were created for the first time and site-specific transgene integration/homoplasmy was confirmed by Southern blots. Thus, leaf-production platform offers a novel low-cost approach by the elimination of fermentation, purification, concentration, formulation and cold-chain storage/transportation. This is the first report of commercially launched protein products made in leaves and validated with current commercial products.

Study on the ability of partially hydrolyzed guar gum to modulate the gut microbiota and relieve constipation

The aim of this study was to evaluate the effects of high- (HHGG, Mw 10,000-30,000 Da) and medium-molecular-weight (MHGG, Mw 2,000-10,000 Da) partially hydrolyzed guar gum (PHGG) on modulation of gut microbiota and relief of constipation in mice. Mice were treated with galacto-oligosaccharide (GOS) and xylo-oligosaccharide (XOS) at a dose of 1 g/kg bw as positive controls. Low- and high-dose HHGG and MHGG groups received 250 mg or 1 g/kg bw, respectively. Treatment was administered intragastrically for 15 days, and constipation model was induced by loperamide lavage at d 16. PHGG could increase fecal moisture and small intestinal transit and shortened the time to first black stool defecation after constipation. The highest short-chain fatty acid production was observed in the high-dose MHGG group. Additionally, PHGG, GOS, and XOS predominantly promoted the accumulation of Bacteroidetes and inhibited the growth of Desulfovibrio. This study suggested that MHGG treatment could elicit constipation relief in mice. PRACTICAL APPLICATIONS: In this study, partially hydrolyzed guar gum (PHGG) produced by mannanase hydrolysis was applied for the relieving constipation in mice. The medium-molecular-weight product (Mw 2,000-10,000 Da) could elicit constipation relief and modulate the gut microbiota in mice, which shows the potential to act as dietary fiber for constipation treatment.

Production optimization and characterization of mannooligosaccharide generating β-mannanase from Aspergillus oryzae

A multi-tolerant β-mannanase (ManAo) was produced by Aspergillus oryzae on copra meal, a low-cost agro waste. Under statistically optimized conditions, 4.3-fold increase in β-mannanase production (434 U/gds) was obtained. Purified ManAo had MW ∼34 kDa and specific activity of 335.85 U/mg with optimum activity at 60 °C and at pH 5.0. Activity of ManAo was enhanced by most metal ions and modulators while maximum enhancement was noticed with Ag⁺ and Triton X-100. K_m and V_max were 2.7 mg/mL and 1388.8 µmol/min/mg for locust bean gum while the enzyme showed lower affinity towards konjac gum (8.8 mg/mL, 555.5 µmol/min/mg). Evaluation of various thermodynamic parameters indicated high-efficiency of the ManAo with activation energy 12.42 KJ/mol and 23.31 KJ/mol towards LBG and konjac gum, respectively. End product analysis of β-mannanase action by fluorescence assisted carbohydrate electrophoresis (FACE) revealed the generation of sugars from DP 1-4 with some higher DP MOS from different mannans.

Structural basis of exo-β-mannanase activity in the GH2 family

The classical microbial strategy for depolymerization of β-mannan polysaccharides involves the synergistic action of at least two enzymes, endo-1,4-β-mannanases and β-mannosidases. In this work, we describe the first exo-β-mannanase from the GH2 family, isolated from Xanthomonas axonopodis pv. citri (XacMan2A), which can efficiently hydrolyze both manno-oligosaccharides and β-mannan into mannose. It represents a valuable process simplification in the microbial carbon uptake that could be of potential industrial interest. Biochemical assays revealed a progressive increase in the hydrolysis rates from mannobiose to mannohexaose, which distinguishes XacMan2A from the known GH2 β-mannosidases. Crystallographic analysis indicates that the active-site topology of XacMan2A underwent profound structural changes at the positive-subsite region, by the removal of the physical barrier canonically observed in GH2 β-mannosidases, generating a more open and accessible active site with additional productive positive subsites. Besides that, XacMan2A contains two residue substitutions in relation to typical GH2 β-mannosidases, Gly439 and Gly556, which alter the active site volume and are essential to its mode of action. Interestingly, the only other mechanistically characterized mannose-releasing exo-β-mannanase so far is from the GH5 family, and its mode of action was attributed to the emergence of a blocking loop at the negative-subsite region of a cleft-like active site, whereas in XacMan2A, the same activity can be explained by the removal of steric barriers at the positive-subsite region in an originally pocket-like active site. Therefore, the GH2 exo-β-mannanase represents a distinct molecular route to this rare activity, expanding our knowledge about functional convergence mechanisms in carbohydrate-active enzymes.

Phytase from Citrobacter koseri PM-7: Enhanced production using statistical method and application in ameliorating mineral bioaccessibility and protein digestibility of high-phytate food

The present study was aimed at enhancing phytase (Phy-Ck) production from Citrobacter koseri PM-7 using response surface methodology (RSM) and improving the bioaccessibility of minerals (Fe and Zn) and protein digestibility in high-phytate food using Phy-Ck. A five-variable and three-level central composite design of RSM using wheat bran (6.681%, w/v), inoculum level (2.5%, v/v), and triton X-100 (0.2%, v/v) resulted in up to 5.57-fold (1.047 U/ml) improvement in Phy-Ck yield from C. koseri PM-7 when compared with fermentation media I and II. The model was successfully validated in the design space by taking a random set of variable combinations. Treatment of high-phytate food with partially purified Phy-Ck showed improvement in mineral bioaccessibility maximally for defatted sesame flour (DSF) (Fe 45.5%; Zn 50.7%) followed by wheat flour (WF) (Fe 13.5%; Zn 14.4%), green gram flour (GGF) (Fe 0.7%; Zn 3.8%) and defatted groundnut flour (DGF) (Zn 5.6%). The in vitro protein digestibility (IVPD) of WF increased from 48.83 to 65.04%, GGF from 45.04 to 57.12%, and DSF from 47.34 to 55.7% after Phy-Ck treatment.

Coproduction of protease and mannanase from Bacillus nealsonii PN-11 in solid state fermentation and their combined application as detergent additives

Bacillus nealsonii PN-11 produces thermo-alkalistable mannanase and protease active in wide temperature and pH range. Optimization of coproduction of protease and mannanase from this strain and application of cocktail of these enzymes as detergent additives were studied. On optimization mannanase yield of 834Ug^-1 (11.12 fold increase) and protease yield of 70Ug^-1 (4.7 fold increase) could be obtained in a single fermentation. Purification and characterization of mannanase have been done earlier and protease was done during this study and has a molecular mass of 48kDa. pH and temperature optima for protease were 10.0 and 65°C respectively. It was completely stable at 60°C for 3h and retained >80% of activity at pH 11.0 for 1h. Both the enzymes were compatible with detergents individually and in a combination. The wash performance of the detergent on different type of stains improved when protease or mannanase were used individually. However destaining was more efficient when a combination of mannanase and protease was used.

Cross-linked enzyme aggregates (CLEAs) and magnetic nanocomposite grafted CLEAs of GH26 endo-β-1,4-mannanase: Improved activity, stability and reusability

A comparative study on immobilization of recombinant endo-β-1,4-mannanase (ManB-1601), using cross-linked aggregated form (MB-C) and novel chitosan magnetic nanocomposites of MB-C (MB-Mag-C) was carried out. FT-IR and Raman spectroscopy were used to confirm the surface modifications while, scanning electron and atomic force microscopy were performed to demonstrate the surface topology and magnetic nature of MB-C and MB-Mag-C. Among MB-C and MB-Mag-C, the former showed better activity and stability in broad range of pH, thermo-stability and kinetic parameters while, the latter showed higher temperature optima and solvent stability. MB-C and MB-Mag-C when compared with free enzyme showed up to 73.2% higher activity (pH 4-9), up to 95.6% higher stability (pH 3-10, 9h incubation at room temperature), up to 15°C higher optimal temperature, higher stability (up to 83%) in the presence of solvents and up to 1.62-fold higher deactivation energy (E_d). Immobilized enzymes were able to repeatedly hydrolyze locust bean gum till 12 cycles and generated predominantly di-, tri- and tetra- species of β-manno-oligosaccharides.

Structural Characterization and in Vitro Fermentation of β-Mannooligosaccharides Produced from Locust Bean Gum by GH-26 endo-β-1,4-Mannanase (ManB-1601)

Size exclusion chromatography of β-mannooligosaccharides (β-MOS) mixtures, obtained from ManB-1601 hydrolysis of locust bean gum, resulted in separation of oligosaccharides with various degrees of polymerization (DP 2, 3, and 5). The oligosaccharides were structurally [ESI-MS, FTIR, XRD, TGA, and NMR (¹H and ¹³C)] and functionally (in vitro fermentation) characterized. DP2 oligosaccharide was composed of two species, (A) mannopyranose β-1,4 mannopyranose and (B) α-1,6-galactosyl-mannopyranose, while DP3 oligosaccharide showed the presence of only one species, i.e. α-d-galactosyl-β-d-mannobiose. ManB-1601 was capable of cleaving near the branch points in the substrate, resulting in oligosaccharides with galactose at the terminal position apart from attacking unsubstituted β-1,4-glycosidic linkages. DP2 and DP3 improved the growth of three out of seven species of Lactobacillus while DP5 resulted in poor growth of all Lactobacillus spp. under in vitro conditions. DP2, DP3, and DP5 were found to inhibit the growth of Escherichia coli, Listeria monocytogenes and Salmonella typhi.

Recombinant endo-mannanase (ManB-1601) production using agro-industrial residues: Development of economical medium and application in oil extraction from copra

Expression of pRSETA manb-1601 construct in Hi-Control Escherichia coli BL21 (DE3) cells improved recombinant endo-mannanase (ManB-1601) production by 2.73-fold (1821±100U/ml). A low-cost, agro-industrial residue supplemented industrial medium for enhanced and economical production of ManB-1601 was developed in two mutual phases. Phase-I revealed the potential of various pre- (induction time: 5h, induction mode: lactose 0.5mM) and post-induction [peptone supplementation: 0.94%(w/v), glycerol 0.123%(v/v)] parameters for enhanced production of ManB-1601 and resulted in 4.61-fold (8406±400U/ml) and 2.53-fold (3.30g/l) higher ManB-1601 and biomass production, respectively. Under phase-II, economization of phase-I medium was carried out by reducing/replacing costly ingredients with solubilized-defatted flax seed meal (S-DFSM), which resulted in 3.25-fold (5926U/ml) higher ManB-1601 production. Industrial potential of ManB-1601 was shown in oil extraction from copra as enzyme treatment led to cracks, peeling, fracturing and smoothening of copra, which facilitated higher (18.75%) oil yield.