Screening, Production and Optimization of L-Asparaginase From Soil Bacteria Isolated in Ibadan, South-western Nigeria
Pages 39-51
Sherifah M. Wakil and Adesewa A. Adelegan

DOI: http://dx.doi.org/10.6000/1927-5129.2015.11.06

Published: 21 January 2015

Abstract: L-Asparaginase producing bacteria were isolated from soil samples under optimum conditions using submerged fermentation. Their abilities to produce asparaginase at different pH, temperature, incubation temperature, utilization of different carbon and nitrogen sources as well as their specific conditions for optimal activity were also investigated. Streptococcus spp. D1, Bacillus polymyxa and Streptococcus spp. D2 showed optimum asparaginase production at pH 8 with activities of 11.6 U/ml, 8.8 U/ml and 7.9 U/ml respectively. The pH 7 was observed as optimum pH for Bacillus firmus (8.8 U/ml) while optimum pH 6 was observed for Bacillus circulans and Paenibacillus validus. Maximum L-asparaginase productivity was attained at a temperature of 45°Cby Bacillus firmus, Streptococcus sp. D1 and Bacillus circulans with activity of 4.6 U/ml, 5.6 U/ml and 3.8 U/ml respectively while 35°C incubation temperature was optimum for Paenibacillus validus and Bacillus polymyxa with enzyme activity of 6.2 U/ml and 6.1 U/ml respectively. Mannitol supported the maximum asparaginase production of Bacillus circulans, Streptococcus sp. D2 and Bacillus polymyxa while maltose was observed as the best carbon source for Streptococcus sp. D1 and Bacillus firmus; and sucrose for Paenibacillus validus. The optimum nitrogen source was casein for Bacillus circulans (7.57 U/ml) and Streptococcus spp. D1 (6.19 U/ml), Yeast extract for Bacillus polymyxa (7.037 U/ml)and Bacillus firmus (5.368 U/ml) while NaNO₃ supported optimum L-asparaginase production for Streptococcus sp. D2 (6.006 U/ml) and Paenibacillus validus (4.754 U/ml). At optimum conditions, Bacillus polymyxa had the highest (4.835 U/ml) while Bacillus circulans had the least (2.981 U/ml) asparaginase activity. In all, the bacterial isolates prefers slightly alkaline to alkaline medium (pH 6-8) for optimum asparaginase production.