http://hdl.handle.net/10204/1774 Sun, 19 May 2013 20:06:27 GMT 2013-05-19T20:06:27Z http://hdl.handle.net/10204/6589 Title: Antioxidant, acetylcholinesterase inhibitory activity and cytotoxicity assessment of the crude extracts of Boophane disticha Authors: Adewusi, EA; Fouche, G; Steenkamp, V Abstract: Traditional healers use Boophane disticha to treat several neurodegenerative diseases. Further studies need to be carried out to justify its use in traditional medicine. Description: Copyright: 2012 African Journal of Pharmacology and Therapeutics, vol. 1(3), pp 78-83 Mon, 01 Oct 2012 00:00:00 GMT http://hdl.handle.net/10204/6589 2012-10-01T00:00:00Z http://hdl.handle.net/10204/6586 Title: Characterisation of two bifunctional cellulase-xylanase enzymes isolated from a bovine rumen metagenome library Authors: Rashamuse, KJ; Visser, DF; Hennessy, F; Kemp, J; Van der Merwe, MP; Badenhorst, J; Ronneburg, T; Francis-Pope, R; Brady, D Abstract: Ruminant digestive tract microbes hydrolyse plant biomass, and the application of metagenomic techniques can provide good coverage of their glycosyl hydrolase enzymes. A metagenomic library of circa 70,000 fosmids was constructed from bacterial DNA isolated from bovine rumen and subsequently screened for cellulose hydrolysing activities on a CMC agar medium. Two clones were selected based on large clearance zones on the CMC agar plates. Following nucleotide sequencing, translational analysis and homology searches, two cellulase encoding genes (cel5A and cel5B) belonging to the glycosyl hydrolyse family 5 were identified. Both genes encoded pre-proteins of about 62 kDa, containing signal leader peptides which could be cleaved to form mature proteins of about 60 kDa. Biochemical characterisation revealed that both enzymes showed alkaline pH optima of 9.0 and the temperature optima of 65 °C. Substrate specificity profiling of the two enzymes using 1,4-ß-D-cello- and xylo-oligosaccharides revealed preference for longer oligosaccharides (n = 3) for both enzymes, suggesting that they are endo-cellulases/xylanases. The bifunctional properties of the two identified enzymes render them potentially useful in degrading the ß-1,4 bonds of both the cellulose and hemicellulose polymers. Description: Copyright: 2013 Springer Verlag. This is the pre/post print version of the work. The definitive version is published in Current Microbiology, vol. 66(2), pp 145-151 Fri, 01 Feb 2013 00:00:00 GMT http://hdl.handle.net/10204/6586 2013-02-01T00:00:00Z http://hdl.handle.net/10204/825 Title: Isolation and selection of Bacillus spp as potential biological agents for enhancement of water quality in culture of ornamental fish Authors: Lalloo, R; Ramchuran, SO; Ramduth, DM; Gorgens, J Abstract: Natural isolates obtained from mud sediment and Cyprinus carpio were purified and assessed in vitro for efficacy based on the inhibi-tion of growth of pathogenic Aeromonas hydrophila and the decrease in concentrations of ammonium, nitrite, nitrate and phosphate ions. Based on suitability to predefined characteristics, the isolates B001, B002 and B003 were selected and evaluated in vitro in the presence of Aer. hydrophila and in a pre-liminary in vivo trial with C. carpio. The inhibitory effect on pathogen growth and the decrease in concentrations of waste ions was demonstrated. Based on 16S RNA sequence homology, the isolates were identified as Bacillus subtilis, Bacillus cereus and Bacillus licheniformis, respectively. Isolate B002 did not contain the anthrax virulence plasmids pOX1, pOX2 or the B. cereus enterotoxin. Conclusions: Selected isolates effected synergistic reduction in pathogen load and the concentrations of waste ions in vitro and in vivo and are safe for use in ornamental aquaculture. Significance and Impact of the Study: A new approach for assessment of biological agents was demonstrated and has yielded putative isolates for development into aquaculture products. Description: Copyright: 2007 Blackwell Publishing Thu, 01 Feb 2007 00:00:00 GMT http://hdl.handle.net/10204/825 2007-02-01T00:00:00Z http://hdl.handle.net/10204/731 Title: Production of a lipolytic enzyme originating from Bacillus halodurans LBB2 in the methylogrophic yeast Pichia pastoria Authors: Ramchuran, SO Abstract: A gene encoding a lipolytic enzyme amplified from the alkaliphilic bacterium Bacillus halodurans LBB2 was cloned into the pPICZaB vector and integrated into the genome of the protease deficient yeast strain Pichia pastoris SMD1168H. This previously undescribed enzyme was produced in active form, and cloning in frame with the Saccharomyces cerevisiae secretion signal (a-factor) enabled extracellular accumulation of correctly processed enzyme, with an apparent molecular mass of 30 kDa. In shake-flask cultivations, very low production levels were obtained, but these were significantly improved by use of a “batch-induced” cultivation technique which allowed a maximum enzyme activity of 14,000 U/l using p-nitrophenyl butyrate (C-4) as a substrate and a final extracellular lipolytic enzyme concentration of approximately 0.2 g/l. Partial characterization of the produced enzyme (at pH 9) revealed a preference for the short-chain ester (C-4) and significant but lower activity towards medium (C5-C6) and long (C16 and C18) fatty acid chain-length esters. In addition, the enzyme exhibited true lipase activity (7,300 U/l) using olive oil as substrate and significant levels of phospholipase activity (6,400 U/l) by use of a phosphatidylcholine substrate, but no lysophospholipase activity was detected using a lysophosphatidylcholine substrate. Description: http://www.springerlink.com/content/?k=Production+of+a+lipolytic+enzyme+originating+from+Bacillus+halodurans+LBB2+in+the+methylogrophic+yeast+Pichia+pastoria Sat, 01 Jul 2006 00:00:00 GMT http://hdl.handle.net/10204/731 2006-07-01T00:00:00Z