Mannan polysaccharides occur in hemicellulose fraction of the plant cell walls. The hydrolysis
of these polymers involves the action of enzymes such as β-mannanase, β-mannosidase and α-
galactosidase which are produced by both fungi and bacteria. The current study reports on the
production of β-mannanase, β-mannosidase and α-galactosidase by newly isolated
Scopulariopsis candida strains LMK004 and LMK008. The effect of medium composition and
carbon source on growth and enzyme production was evaluated in a liquid culture. A
combination of Vogelâs medium and locust bean gum was found to stimulate growth and
increase β-mannanase production. Optimal β-mannanase production of 7800 nkat/g biomass for
LMK004 and 13300 nkat/g biomass for LMK008 was achieved in media containing 10% NaCl,
1X Vogelâs medium, 1% yeast extract and 1% locust bean gum. Both strains secreted trace
amounts (less than 1 nkat/ml) of β-mannosidase and α-galactosidase indicating that these
enzymes may be retained intracellularly. Native-PAGE and SDS-PAGE were used together with
the zymogram to assess purity and to estimate the molecular weight of the proteins. The
molecular weight of LMK004 β-mannanase was estimated to be â41 kDa whereas that of
LMK008 β-mannanase could not be determined due to excessive loss of protein material during
dialysis. The β-mannanase from LMK004 was most active at pH 5 and 50 °C, and retained â¥
80% of its activity at pH 5 â 6.5 after 24 hrs of incubation at 4 °C. In contrast, the LMK008 β-
mannanase retained ⥠60% activity between pH 6 â 7. Both enzymes remained stable for 3 hrs at
temperature between 30 °C and 40 °C, and showed loss of activity at higher temperatures. The
two enzymes displayed different degrees of halotolerance. The LMK008 β-mannanase tolerated
high NaCl concentrations with 60% activity remaining after incubation for 2 hrs at 20% NaCl,
whereas the LMK004 β-mannanase was only active between 0% - 10% NaCl. It is clear from
the current study that the two strains of S. candida produce distinct β-mannanases which may be
useful candidates in low water activity reactions.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-04162007-151130 |
| Date | 16 April 2007 |
| Creators | Mudau, Maria Mabyalwa |
| Contributors | Dr CH Pohl, Dr ME Setati |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-04162007-151130/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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