Highly Efficient Biodegradation of Postconsumer Polylactic Acid Waste: The First Report on <i>Priestia aryabhattai</i> SNRUSAC3 and a Newly Isolated <i>Bacillus</i> sp. SNRUSAC1

The increasing use of polylactic acid (PLA) for single-use packaging has led to a growing accumulation of bioplastic waste. This study presents a comprehensive approach for enhancing the degradation of postconsumer PLA packaging waste, beginning with the isolation, screening, and identification of highly effective bacteria and culminating in the statistical optimization of their specific nutritional requirements. From compost samples, two highly effective strains were identified as <i>Bacillus</i> sp. SNRUSAC1 and <i>Priestia aryabhattai</i> SNRUSAC3 based on morphological, biochemical, and 16S rDNA sequence analyses. Notably, this is the first report of PLA degradation by the species <i>P</i>. <i>aryabhattai</i>. Initially, these strains achieved approximately 13% PLA dry weight loss after 56 days. To enhance their efficiency, a statistical optimization of nutritional components was performed. Under the optimized conditions, the degradation efficiency was dramatically enhanced, with SNRUSAC1 and SNRUSAC3 achieving 62.06% and 57.61% dry weight loss, respectively, in only 30 days. This represents over a fourfold increase in degradation in approximately half the time. This optimization also revealed novel, strain-specific requirements, with ferrous sulfate identified as a critical factor that had not been previously reported to influence the growth and degradative activity of <i>P</i>. <i>aryabhattai</i>. These findings establish <i>Bacillus</i> sp. SNRUSAC1 and <i>P</i>. <i>aryabhattai</i> SNRUSAC3 as novel, highly efficient candidates for the biodegradation of PLA plastic waste.