PJB-2021-1510
Dynamics of amylases production potential by Aspergillus niger isolates from soil
Saba Sana, Aftab Ahmad Anjum, Mansur-Ud-Din Ahmad, Muhammad Nawaz, Ali Ahmad and Hafiza Rahat Farooq
Abstract
Amylases production potential of non-toxigenic starch hydrolyzing indigenous Aspergillus niger was determined. A. niger soil isolates (06) identified based on macroscopic and microscopic characters were screened for amylases production on starch agar. Three isolates (ANS03, ANS06 and ANS10) with higher starch hydrolyzing index (0.24, 0.25 and 0.20 respectively) were selected for optimization of physical and chemical conditions for higher enzyme production. Physicochemical factors including pH (4.5, 6, and 7.5), temperature (22, 28, and 37°C), substrates (maize, rice husk and wheat bran) and substrate concentration (1, 3, and 5%) were evaluated for dynamics in amylases production potential by one time one factor method. Post incubation of seven days with standardized inoculums (106 spores / mL) of selected isolates, filtrates were obtained. Qualitatively, extracellular enzymes in filtrate were detected by iodine test and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). All isolates showed starch hydrolysis to some extent by iodine test. Electrophoresis analysis revealed three proteins with 50.12, 48.98 and 37.15kDa molecular weights. Amylases were quantified from filtrates by dinitrosalicylic acid (DNS) method. Among three isolates, ANS06 is the best producer with 150.61±3.26 IU amylase activity at 37°C, pH 6 and wheat bran (5%) and lowest amylase activity was found (.039±.03) at same temperature and pH but with maize (1%). ANS03 showed highest amylase activity (40.04IU±.37) at 37°C, pH 6 using 5 percent maize as substrate and lowest activity was (0.56±.08). The maximum enzyme production of ANS10 was 86.23±1.31IU at 37°C, pH 6 and 5 percent wheat bran and lowest 0.04±0.01 IU. Statistically, all isolates showed significant difference in amylase activity at all selected physical and chemical conditions. It was concluded that starch hydrolyzing potential of indigenous A. niger isolate can be used for mass production.
To Cite this article:
Sana, S., A.A. Anjum, M.U. Ahmad, M. Nawaz, A. Ahmad and H.R. Farooq. 2021. Dynamics of amylases production potential by Aspergillus niger isolates from soil. Pak. J. Bot., 53(2): DOI: http://dx.doi.org/10.30848/PJB2021-2(17)
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