Protease-Producing Bacteria from Soil in Nasinuan Community Forest, Mahasarakham Province, Thailand

Vijitra Luang-In^1*, Manatchanok Yotchaisarn¹, Worachot Saengha¹, Piyachat Udomwong², Sirirat Deeseenthum¹ and Kedsukon Maneewan¹

¹Natural Antioxidant Innovation Research Unit, Department of Biotechnology, Faculty of Technology, Mahasarakham University, Khamriang, Kantarawichai, Maha Sarakham, 44150, Thailand.

²International College of Digital Innovation, Chiang Mai University, Chiang Mai 50200, Thailand.

Corresponding Author E-mail: vijitra.l@msu.ac.th

Abstract: The current work aimed to screen for and identify protease-producing bacteria from the untapped resource Nasinuan forest, Kantarawichai District, Mahasarakham Province, Thailand. Nineteen bacterial isolates with protease-producing capacity on 1% skimmed milk agar were identified using 16S rRNA sequencing. Seventeen bacteria were gram-positive, rod shaped and identified as Bacillus spp. and only two bacteria were identified as Enterobacter sp. and Staphylococcus cohnii. Their closest relatives were found in India, Oman, Italy, Indonesia, Malaysia, China and USA. The top six highest halo : colony ratios from pure isolates were ranked in the following order: 1.2PT1 (2.43) > 1.2PT2 (2.23) > 2.2PT3 (2.21) > 2.1PT3 (2.17) > 2.3PT3 (2.16) > 2.4PT1 (2.16).  Bacillus thuringiensis 2.3PT3 was found to exhibit the highest protease enzyme activity of 3.72 ± 0.08 U/mg protein at the optimal conditions of 65°C and pH 8.0 after 30 min incubation with 1% casein in 0.05 M PBS buffer. This protease–producing bacterial strain can be of great potential for applications in food, agricultural and pharmaceutical industries in Thailand.

Keywords: Bacteria; Nasinuan Forest; Protease; Soil; Thailand

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