Polyphasic Characterization of Acetobacter indonesiensis UNPADCC 01-5 Isolated From a Traditional Fermented Food, Oncom Merah.

Abstract

Acetobacter indonesiensis UNPADCC 01-5 is a recently discovered acetic acid bacterium isolated from fermented food, oncom merah. With its current lack of polyphasic approach in classification, this study aims to provide the first morphological, physiological, biochemical and molecular analyses. These analyses are achieved by morphological and physiological characterization, Kirby-Bauer antibiotic susceptibility, biochemical profiling, gas chromatography-mass spectrometry and whole-genome sequencing (WGS). The results found that A. indonesiensis UNPADCC 01-5, a non-motile cell, is a gram-negative, short rod-shaped cell that formed cream-white colonies with 0.3-1.3 in diameter. It exhibited environmental resilience, including acid-tolerant, halotolerant and thermotolerant. Against antibiotics, it showed resistance towards chloramphenicol. Biochemical tests revealed its ability to ferment glucose, rhamnose, melibiose and arabinose, as well as to produce bioactive metabolites such as acetoin and acetic acid. WGS identified potential gene expressions associated with acetic acid production, stress tolerance, nitrogen fixation, hydrocarbon degradation and heavy-metal resistance. WGS analysis revealed no detectable genes associated with human virulence factors or pathogenic secretion systems. The results suggested that A. indonesiensis UNPADCC 01-5 from oncom merah possessed adaptive traits which, with future assessments and industrial-scale tests, hold potential as a functional/adjunct culture for acidic fermentations and a biofunctional agent.