Screening and identification of endomannanase-producing microfungi from hypersaline environments.
A culture-dependent enrichment technique was used to isolate endo-1,4-beta-mannanase-producing fungi from a hypersaline environment. Galactomannan was used as carbon source and resulted in isolation of strains of Scopulariopsis brevicaulis, S. candida, and Verticillium dahliae. The Scopulariopsis isolates were found to be more dominant and could be isolated from consecutive evaporation ponds, whereas Verticillium was only isolated from one pond. The Scopulariopsis strains exhibited only endomannanase activity, whereas Verticillium displayed broad-activity spectrum by secreting endoxylanases and cellulases in addition to endomannanases. S. candida LMK004 and LMK008 produced 7,420 and 14,750 nkat g(-1) biomass, respectively. Endomannanase production in these strains increased with an increase in NaCl concentration up to 10% (w/v), after which both growth and enzyme production was decreased. V. dahliae LMK006 grew and produced up to 5,000 nkat g(-1) biomass endomannanase in the absence of NaCl. Increased NaCl concentration had a negative effect on this strain. S. brevicaulis LMK002 showed poor endomannanase production but a similar growth trend as the other Scopulariopsis strains. In general, the Scopulariopsis strains exhibited better halotolerance than V. dahliae and could grow in the presence of 20% NaCl on solid medium.
Mudau
Mabyalwa Maria
MM
Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, P. O. Box 339, Bloemfontein 9300, South Africa.
Setati
Mathabatha Evodia
ME
D001203:Ascomycota / Q000302:isolation & purification* / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D005690:Galactose / Q000031:analogs & derivatives; D008351:Mannans / Q000378:metabolism*; D008361:Mannosidases / Q000096:biosynthesis*; D012462:Saline Solution, Hypertonic / Q000378:metabolism; D012492:Salts / Q000032:analysis; D013379:Substrate Specificity; D014871:Water Microbiology
D003470:Culture Media; D008351:Mannans; D012462:Saline Solution, Hypertonic; D012492:Salts; C017082:brine; C012990:galactomannan; D008361:Mannosidases; C041867:endo-1,4-beta-D-mannanase; D005690:Galactose