Microbial Diversity and Functional Role of Yeasts, Lactic Acid Bacteria, and Acetic Acid Bacteria in Fermented Noni Fruits

Abstract

Noni fruit (Morinda citrifolia L.) is widely cultivated in Indonesia and known for its bioactive compounds with antioxidant, antimicrobial, and immunomodulatory properties. Traditionally, noni juice is produced through spontaneous fermentation that may take several months to years, resulting in inconsistent quality. This study aimed to accelerate the fermentation process by isolating, characterizing, and identifying key microorganisms involved, specifically yeasts, lactic acid bacteria (LAB), and acetic acid bacteria (AAB). Fermentation was carried out under controlled aerobic and anaerobic conditions at 30-32 deg C for 5 days. Samples were taken every 24 hours to monitor pH, total acidity, and reducing sugar content, and microbial isolates were obtained using selective culture media. Pure isolates were further characterized through morphological, biochemical (IMViC and sugar fermentation), and molecular analyses. To provide a comprehensive overview of microbial diversity, amplicon-based metagenomic sequencing (16S rRNA and ITS) was performed to identify bacterial and yeast communities at the species level. Preliminary results revealed distinct shifts in microbial populations during fermentation, with functional contributions of LAB and AAB to acidification and flavor development, while yeasts contributed to sugar metabolism and bioactive compound production. This study highlights the potential of microbial characterization and metagenomic profiling to shorten fermentation time and support the development of standardized functional noni-based products.

Keywords: noni fruit- fermentation- yeast- lactic acid bacteria- acetic acid bacteria- metagenomics

Topic: Food science and biotechnology