Utilization of Agricultural By-Products for Alpha-Amylase Production under Solid State Fermentation by Bacillus Subtilis

Abstract

The production of alpha-amylase by Bacillus subtilis was investigated under different cultivation conditions on two different solid substrates as the support, i.e. oil palm empty fruit bunch (OPEFB) fibers and rice straw using solid state fermentation (SSF) process. Both solid substrates were first pre-treated using NaOH to remove lignin and silica and to break down the hemicellulose structures. The influences of incubation time, incubation temperature and the additional carbon and nitrogen sources on the production of alpha-amylase by B. subtilis were investigated. After 48 h of incubation, the highest enzyme activities were obtained at 39.9 U/g and 23.5 U/g for rice straw and OPEFB fibers, respectively. The optimum temperature for alpha-amylase production was observed at 45°C for the OPEFB fibers and 55°C for the rice straw. Among the defined carbohydrates, the addition of glucose (0.02 g/g dry substrate) has significantly improved the production of alpha-amylase. Similar effect was observed when yeast extract (0.01 g/g dry substrate) was supplemented as the additional nitrogen source. Rice straw appeared to be the best solid substrate in producing alpha-amylase (276 U/g) in SSF under these optimum cultivation conditions.

Optimization of amylase production by Aspergillus niger cultivated on yam peels in solid state fermentation using response surface methodology

“…The model offered a relatively high determination coefficient with an R 2 value of 0.8776 (Table 4), indicating the model could explain 87.6% of the responses variability. Predicted R 2 (0.666) was in reasonable agreement with the adjusted R 2 (0.767) (Table 4) since the difference between both R 2 was < 0.200 (Hassan and Karim, 2015). The degree of accuracy with which the experiments were associated was indicated by the coefficient of variation (CV); a high value of CV usually indicated a lower reliability of the experiment (Prajapati et al, 2014).…”

“…This study showed a low CV of 21.08% (Table 4), signifying that the experiments performed were dependable. The signal to noise ratio is measured by the adequate precision (Hassan and Karim, 2015). The study showed a ratio of8.684 (Table 4) for adequate signal (a ratio greater than 4 is desirable), implying that the model was reliable in optimizing the chosen process variables for maximum amylase production.…”

“…Higher temperatures may cause inactivation or halting of cell viability and enzyme denaturation (Hassan and Karim, 2015;Roses and Guerra, 2009), this may be the reason for the low activities observed at high temperatures (60°C). Optimum temperature ranges between 50 to 55°C have been reported, especially, for the thermophilic fungal cultures of Thermomyces lanuginosus, Talaromyces emersonii and Thermomonospora fusca (Haasum et al, 1991).…”

“…Response surface methodology can be used to overcome these limitations since its application can identify and quantify the various interactions among several parameters with less experimental runs (Shankar et al, 2015;Francis et al, 2003). There has been an extensive use of RSM for optimizing amylase productions (Hassan and Karim, 2015;Kalaiarasi and Parvatham, 2013;Tamilarasan et al, 2012).…”

Potato peels: A potential food waste for amylase production

“…In this study 0.6% yeast extract yield maximum titer of amylase in submerged fermentation. Hassan and Karim () suggested that supplementation of 0.01 g/g yeast extract as nitrogen source favored amylase production in solid state fermentation of rice straw by Bacillus subtilis . Higher secretion of starch digesting enzyme has been reported for Bacillus sp.…”