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Abstract:
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Bacillus subtilis CBTK 106, isolated from
banana wastes, produced high titres of a-amylase when
banana fruit stalk was used as substrate in a solid-state
fermentation system. The e¤ects of initial moisture content,
particle size, cooking time and temperature, pH,
incubation temperature, additional nutrients, inoculum
size and incubation period on the production of a-
amylase were characterised. A maximum yield of
5 345 000 U mg~1 min~1 was recorded when pretreated
banana fruit stalk (autoclaved at 121 ¡C for
60 min) was used as substrate with 70% initial moisture
content, 400 lm particle size, an initial pH of 7.0, a temperature
of 35 ¡C, and additional nutrients (ammonium
sulphate/sodium nitrate at 1.0%, beef extract/peptone
at 0.5%, glucose/sucrose/starch/maltose at 0.1% and
potassium chloride/sodium chloride at 1.0%) in the
medium, with an inoculum-to-substrate ratio of 10%
(v/w) for 24 h. The enzyme yield was 2.65-fold higher
with banana fruit stalk medium compared to wheat bran |