Isolasi dan Seleksi Mikroorganisme Penghasil Enzim L-Asparaginase dari Tempe

Abstract

Tempeh is a soybean-based fermented product rich in amino acids and beneficial microorganisms, including L-asparaginase–producing species. The aim of this study was to obtain L-asparaginase-producing bacteria and fungi from tempeh. Tempeh in two different types of packaging was obtained from tempeh industry in Medan Tuntungan. Bacteria and fungi were isolated from the tempeh and subsequently characterized macroscopically and microscopically. The ability of the isolates to produce L-asparaginase was assessed qualitatively on M9 medium by observing the color change to pink, and quantitatively by determining enzyme activity and specific activity values. The most promising bacterial isolate with the highest L-asparaginase activity was identified molecularly using 16S rRNA primers, while fungal isolates were identified morphologically using standard identification book. A total of 24 microbial isolates were obtained from the tempeh samples, consisting of 7 bacterial isolates, 10 lactic acid bacterial (LAB), and 7 fungal. The bacterial and fungal isolates displayed variation in both colony morphology and microscopic characteristics. Qualitative screening yielded 6 bacterial isolates and 4 fungal isolates with potential L-asparaginase activity, whereas none of the LAB isolates showed enzyme production. The highest Lasparaginase activity among bacterial isolates was recorded for isolate TDN 04, with a specific activity of 338,448U/mg in value, and the highest fungal activity was recorded for isolate JTP3, with a specific activity of 445,75 U/mg in value . Molecular identification showed that isolate TDN 04 shared 99.53% similarity with Klebsiella aerogenes, while fungal isolate JTP3 exhibited morphological characteristics consistent with the genus Aspergillus. Klebsiella aerogenes isolate TDN 04 and Aspergillus sp. isolate JTP3 are therefore the bacterial and fungal isolates from tempeh with the highest L-asparaginase activity, demonstrating potential in converting asparagine into aspartic acid and ammonia.