TITLE:
Optimization of Growth Conditions to Identify the Superior Bacillus Strain Which Produce High Yield of Thermostable Alpha Amylase
AUTHORS:
Witharanage Wasana Prasadini Rodrigo, Lakmi Samodha Magamulla, Morawakage Sajith Thiwanka, Yapa Mudiyanselage Shashika Madhuwanthi Yapa
KEYWORDS:
Thermostable, α-Amylase, Bacillus Strain, Fermentation, Incubation Period
JOURNAL NAME:
Advances in Enzyme Research,
Vol.10 No.1,
March
10,
2022
ABSTRACT: Thermostable α-amylases
hold a very important place in commercial industrial applications in Sri Lanka.
Therefore, the main aim of this study was to identify superior Bacillus strain and optimize growth conditions that could yield
high α-amylase production. Three Bacillus strains, B. amyloliquefaciens ATCC 23350, B. licheniformis ATCC 14580 and B.
megaterium ATCC 14581 were used for the study. Shake flask culture experiments
were conducted to identify the effect of various fermentation conditions such
as growth temperature, incubation period, carbon source, nitrogen source,
initial pH and carbon concentration on extracellular α-amylase production. DNSA assay was carried out to determine the enzyme
activity. The highest temperature for enzyme activity was reported by B. licheniformis at 85°C, followed by B. amyloliquefaciens at 75°C and B. megaterium at 45°C. Both B. amyloliquefaciens and B. licheniformis were able to give their
optimum enzyme production at 37°C, while B.
megaterium at 30°C in 150 rpm with initial pH of 7. B. licheniformis and B. amyloliquefaciens gave their optimum yield of the enzyme after 48 h of incubation while B. megaterium gave after 24 h of
incubation. Among the carbon sources tested cassava starch was able to give the
highest enzyme production. For B.
amyloliquefaciens, the highest yield of the enzyme was obtained with 2% of
starch, tryptone as a nitrogen source and initial pH of 7. Maximum enzyme
production for B. licheniformis was
obtained with 1.5% of starch, KNO3 as a nitrogen source and initial
pH of 6. For B. megaterium 1% of starch,
tryptone and pH 7.5 induced the optimum α-amylase production. According to the results obtained, B. amyloliquefaciens is the highest
thermostable alpha amylase producer. However, according to the industrial
requirement, B. licheniformis can also be
used as an enzyme producer due to its stability in higher temperatures.