Singh et al.

Figure 4: Variation in alpha amylase production by Bacillus licheniformis due to

different pH of SSF medium

pH is one of the important factors that determine the growth and enzyme secretion

of microorganisms as they are sensitive to the concentration of hydrogen ions

present in the medium. As the metabolic activities of the microorganism are very

sensitive to changes in pH, alpha amylase production was found to be affected when

the pH level is above or below the optimum pH. Kalairasi and Parvatham (2013)

also reported high enzyme titre when the pH of the medium was maintained at 7.

Nagrajan et al. (2010) reported maximum amylase production by using Bacillus

subtilis when the initial medium was neutral (pH=7) for both wheat bran and rice

bran. Noreen et al. (2002) obtained maximum yield of alpha amylase enzyme

from banana peels under the SSF condition by using Bacillus subtilis at pH 7.

Ashraf et al. (2005) observed maximum production of alpha amylase by using

Bacillus licheniformis. The culture (GHB8) gave the maximum production of

alpha amylase at pH 7.5 when the wheat was replaced with cottonseed meal (3:1).

Varalakshmi et al. (2012) reported pH 7.5 for the optimal enzyme production by

using Pseudomonas sp. under solid state fermentation. Serin et al. (2012) also

found the maximum enzyme production from rice bran by using Bacillus circulans

ATCC 4516 when the initial pH was 7.5. Furthermore increase in the pH resulted

in decrease of enzyme production. Niaz et al. (2010) also produced α- amylase

from (10%) wheat bran by using Bacillus licheniformis RT7YC strain at pH 7.0.

Hassan and Karim (2012) produced alpha amylase enzyme from oil palm fruit

bunch under solid state fermentation at pH 7.0. Raj and Hemashenpagam (2012)

also found maximum enzyme production at pH 7.0 under SSF condition by using

Bacillus. The growth and production of alpha amylases requires nearly neutral pH

i.e. ranges from pH 6-8 (Sivaramakrishnan et al., 2006; Regulapati et al., 2007).

El-Shishtawy et al. (2014) observed amylase production from wheat bran at pH 5

by using Bacillus sp. Rai and Solanki (2014) found amylase production from the

mixture of wheat bran and barley bran by using B. amyloliquefaciens at pH 7.0.

Tabassum et al. (2014) reported maximum level of alpha amylase production from

wheat bran using Bacillus licheniformis RTPE-1 strain at pH 7.0.

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International Journal of Bioinformatics and Biological Sciences : v.2 n.3&4. Dec. 2014