| Summary: | One of the most recent studies on bioplastic focused on bacteria that break down PLA that were isolated from soils. Environmental problems develop when PLA waste fails to decompose completely in Malaysian landfills due to a lack of external heat. This research isolated and screened bacterium that can break down PLA at room temperature. Samples of soil were taken from a nearby landfill in Pekan, Pahang, Malaysia, and isolated in PLA-emulsified agar at 30°C. Two isolates, B8 and A10B, were chosen as possible mesophile PLA-degraders. They were identified as Brevibacillus parabrevis and Renibacterium salmoninarum using 16S rRNA identification analysis. The result of streaking on skim milk agar showed that both microorganisms were able to produce protease enzyme. The relative halo zones quantified on the skim milk agar by B8 and A10B were 1.33 and 3.86 mm, respectively. Additionally, amylase, lipase, and protease enzyme assays were carried out. The results showed that isolate B8 had 114.49 U/mL of protease, 15.36 U/mL of lipase, and 3.17 U/mL of amylase. Isolate A10B had 120.45 U/mL of protease, 9.23 U/mL of lipase, and 6.56 U/mL of amylase. In addition, B8 and A10B were tested for PLA biodegradation in soil at 30°C for eight weeks, resulting in a weight loss of 37.8% and 32.6% of PLA film, respectively. These results showed that Brevibacillus parabrevis and Renibacterium salmoninarum, which can degrade PLA at room temperature, can be isolated from Malaysian landfills. We suggest studying these stains to use them to combat bioplastic waste in municipal landfills.
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