Enzymatic preparation of manno-oligosaccharides from locust bean gum and palm kernel cake, and investigations into its prebiotic activity

BACKGROUND: Manno-oligosaccharides (MOS) is known as a kind of prebiotics. Mannanase plays a key role for the degradation of mannan to produce MOS. In this study, the mannanases of glycoside hydrolase (GH) families 5 Man5HJ14 and GH26 ManAJB13 were employed to prepare MOS from locust bean gum (LBG) and palm kernel cake (PKC). The prebiotic activity and utilization of MOS were assessed in vitro using the probiotic Lactobacillus plantarum strain. RESULTS: Galactomannan from LBG was converted to MOS ranging in size from mannose up to mannoheptose by Man5HJ14 and ManAJB13. Mannoheptose was got from the hydrolysates produced by Man5HJ14, which mannohexaose was obtained from LBG hydrolyzed by ManAJB13. However, the same components of MOS ranging in size from mannose up to mannotetrose were observed between PKC hydrolyzed by the mannanases mentioned above. MOS stability was not affected by high-temperature and high-pressure condition at their natural pH. Based on in vitro growth study, all MOS from LBG and PKC was effective in promoting the growth of L. plantarum CICC 24202, with the strain preferring to use mannose to mannotriose, rather than above mannotetrose. CONCLUSIONS: The effect of mannanases and mannan difference on MOS composition was studied. All of MOS hydrolysates showed the stability in adversity condition and prebiotic activity of L. plantarum, which would have potential application in the biotechnological applications.

Fermenation Products of β-Mannanase Producing Bacteria Inhibit Selected Poultry Borne Pathogens.

Aim: The study evaluated the inhibitory effect of fermentation products of β-mannanaseproducing bacteria on selected poultry borne pathogens. Study Design: The first experiment, bacterial isolates previously confirmed positive for mannanase by plate assay technique were further screened for mannanase production in submerged state fermentation. In the second experiment, inhibitory effect of fermentation products of mannanase-producing bacteria on selected poultry pathogens was evaluated. Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure Nigeria between September 2011 and March 2012. Methodology: Bacterial isolates from agricultural wastes previously confirmed positive for mannanase activity by plate assay were further screened for their potential performance under submerged state fermentation and enzyme activity determined by dinitrosalicylic acid method. The inhibitory action of β-mannanase-producing bacteria was determined by supplementation of supernatant and plating method. Results: Isolate 1A showed highest mannanase activity (13.430 U/ml), displayed broad inhibition to selected poultry borne pathogens; Klebsiella oxytoca, Shigella alkalescens, Escherichia coli, Salmonella typhii, Staphylococcus aureus and Streptococcus sp. Apart from isolate 1A, fermentation products of other isolates generated from the mannolytic action of β-mannanase on mannan containing substrate displayed different percentage inhibition on selected poultry borne pathogens. Conclusion: The results suggested that fermentation products from β-mannanaseproducing bacteria might possess antibacterial properties which could be applied in poultry farms.

Physiological, morphological, and mannanase production studies on Aspergillus niger uam-gs1 mutants

Mutant strains from Aspergillus niger UAM-GS1 were produced by UV radiation to increase their hemicellulolytic and cellulolytic activity production. The mutant strains showing more enzymatic activity were those labelled GS1-S059 and GS1-S067. These strains also showed the largest relationship between diameter of hydrolysis zone and colony diameter. The mutant GS1-S067 showed a colony radial extension rate and a biomass growth rate g biomass/(cm² h), 1.17 times higher than that achieved by strain UAM-GS1. The high invasive capacity makes this mutant strain a promising alternative for its use in solid substrate fermentation (SSF). The morphological properties of the two mutant strains were evaluated by using scanning electron microscopy. The diameter of the sporangium of the mutant strains GS1-S059 and GS1-S067 was significantly larger (P < 0.05) than that found for the parental strain. The hypha length and diameter of the mutant strains significantly changed (P < 0.05) compared to the parental strain. A Pearson correlation analysis on hypha length, sporangium diameter, and cellulase and xylanase activities indicated that there was a strong relationship among these variables in relation to mannanase activity. Mutant strains GS1-S059 and GS1-S067 significantly increased their level of mannanase, xylanase and cellulase production, compared to the parental strain, improving their potential industrial applications.