Studi Produksi L-asparaginase dari Actinomycetes Isolat Lokal Sumatera Utara: Seleksi dan Optimasi

Abstract

Actinomycetes are Gram-positive filamentous bacteria known for producing a wide range of bioactive compounds, including the enzyme L-asparaginase, which has potential applications in healthcare and industrial biotechnology. This study aims to identify potential actinomycetes from North Sumatra producing L-asparaginase and optimizing the fermentation conditions of actinomycetes that produce the enzyme. Actinomycetes were isolated from Olo Beach, and additional isolates were obtained from the collection of Microbiology Laboratory FMIPA USU originating from Cermin Beach and Lau Kawar Lake. L-asparaginase-producing actinomycetes were screened in M9 liquid medium supplemented with phenol red as a pH indicator, and the enzyme activity was quantitatively determined using the Nesslerization method. Actinomycetes with the highest enzyme activity were selected for the optimization of L-asparaginase production using the one-factor-at-a-time (OFAT) method, with variations in pH, carbon source, nitrogen source, and incubation time. A total of 12 actinomycete isolates were obtained from Olo Beach, all exhibiting characteristics typical of actinomycetes. Qualitative screening of 32 actinomycete isolates from North Sumatra revealed that 24 isolates were capable of producing L-asparaginase, as indicated by a color change in the medium from yellow to pink. Quantitative analysis of the 24 selected isolates showed L-asparaginase activity ranging from 22.913 to 40.688 U/mL, with the highest activity observed in isolate SPO 6. Molecular identification based on the 16S rRNA gene revealed that isolate SPO 6 shared 99.86% similarity with Streptomyces antibioticus. Optimization of fermentation conditions using the OFAT method demonstrated that maximum L-asparaginase production was achieved at pH 8 after 7 days of incubation. Media containing starch as a carbon source and yeast extract as a nitrogen source yielded the highest enzyme activity. These findings indicate that actinomycetes from Olo Beach, particularly S. antibioticus SPO 6, have the potential to serve as L-asparaginase producers for further applications.