Abstract:Studies were conducted on the effects of some physico-chemical factors such as pH, temperature and various mineral elements on the vegetative growth of an Ochratoxin A-degrading Rhizopus sp. The pH studies revealed an increase in mycelial weight as the pH of the medium increase, with a mycelial weight of 18.0+2.0333 mg/50cm3 at pH 3.0, 73.0+1.0837 mg/50cm3 at pH 4.0 before reaching the peak (106.0+1.4204 mg/50 cm3) at pH 5.0. Thereafter, an increase in pH resulted in a reduction in mycelia weight with no growth detected at pH 9.0. Temperature studied showed that a temperature of 30 ºC produced the highest mycelial weight of 145.5 mg/50 cm3 closely followed by 120.6 mg/50 cm3 at 35 ºC while the lowest mycelial weight (15.5 mg/50 cm3) was recorded at 20 ºC and no growth detected at 15 ºC. Among the various microelements investigated, Zinc appears to be the most important with a Zinc-free medium producing the poorest mycelia weight of 37.01+0.6666 mg / 50 cm3 while Cobalt appears not to play any significant role in the growth of this Rhizopus sp. as the Cobalt-free medium produced identical mycelial weight (57.3 mg/50 cm3) with the medium containing all the nutrients. Investigation of the macroelement requirement of the organism showed that Calcium is the most important with a Calcium-free medium producing the poorest growth of 15.0+0.7676 mg/50 cm3 while the best growth was (50.7+0.4096 mg/50 cm3) was observed in a complete medium without Magnesium. [Ilesanmi Fadahunsi, Emmanuel Garuba and Olayinka Elutade. Physico-chemical studies on the growth of an Ochratoxin A-degrading Rhizopus sp. Nature and Science 2011;9(7):240-244].(ISSN: 1545-1003)
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