Microbiologie appliquée: libre accès
Libre accès

ISSN: 2471-9315


Effect of Temperature, pH, Carbon and Nitrogen Sources on Extracellular Protease Production by Four Geobacillus Species Isolated from Maha Oya Geothermal Springs in Sri Lanka

DMSU Dissanayaka and IVN Rathnayake

Thermophilic bacteria are biotechnologically important group of microorganisms due to their capability to produce a variety of thermostable enzymes, such as proteases. The aim of the present study was the optimization of protease production by thermophilic bacteria isolated from hot springs (54°C-55.5°C) in Maha Oya, Sri Lanka. Four isolates of thermophilic bacteria that belong to the genera Geobacillus, which were previously been isolated and identified, were used in the present investigation to study their protease production. Among the four isolates, Geobacillus toebii (DMBUK 107191) reached a maximum protein concentration with a level of 858 μg/mL and Geobacillus kaustophilus (DMBUK 107161) showed maximum protease activity of 2.232 units/mL (55°C, pH 7). Studies on the result of temperature and pH on protease activity discovered that the extreme protease activity was detected at 60°C over a pH range of 6-8. The isolates utilized several carbon and nitrogen sources for the production of proteases. Among the various carbon sources used, bacteria showed maximum protease activity in the presence of sucrose and fructose. Furthermore, bacteria showed a maximum yield of protease activity when gelatin was used as the nitrogen source.