Isolation and Identification of Protease Producing Halophilic Fungi Isolated from NTB, Indonesia Salt-Pond Soil

Abstract

The search for new proteases with unique characteristics has gained significant attention in line with growing industries. Extremophiles, microorganisms that thrive in extreme environments, such as salt-pond soil, produce enzymes with unique characteristics. This research aimed to obtain the best proteases-producing isolates under high salinity (>3 %) conditions. The protease-producing microorganisms were isolated from salt pond soil samples in three locations within the West and East Lombok districts. Fungal isolates were isolated and characterised using morphological and molecular methods. Screening for protease production was conducted using skim-milk agar medium with 3 % and 10 % NaCl, and the formation of a clear zones around the fungal colonies was used to measure proteolytic activity. The results showed that 17 fungal isolates were obtained, of which 9 exhibited halophilic behaviour. The protease-positive isolates were identified as LT0102 Stachylidium bicolor, LT0214 Beauveria sp., LT0216 Torula lancangjiangensis, and LT0317 Aspergillus versicolor by molecular analysis using the ITS rDNA primer. Among these isolates, LT0214 Beauveria sp. produced the highest protease activity, indicated by the clear zone around the colony grown at room temperature in 3 % and 10 % NaCl, with an enzymatic index (EI) of 1.82 and 1.48 maintained for 216 hours. The research showed that Beauveria sp. was highly promising for industrial-scale production of protease enzymes that can withstand high salinity.