Inhibitory potentials of acid-producing bacteria isolated from oncom merah against <i>Aspergillus flavus</i> and <i>Klebsiella pneumoniae</i>

Oncom merah, a traditional fermented food from West Java, Indonesia, is prone to contamination by pathogenic microorganisms, raising food safety concerns. This study assessed microbial contamination in commercially produced oncom merah and explored indigenous microorganisms as biocontrol agents. Samples from five home-scale producers in Bandung City revealed Aspergillus flavus contamination in one sample, with four isolates confirmed as atoxigenic by the absence of aflR, aflD, and aflP genes using polymerase chain reaction. Notably, the dominant fermentative fungus was identified as Neurospora terricola, rather than the commonly reported N. sitophila or N. intermedia, representing the first report of its association with oncom merah. In addition, two indigenous bacteria isolates, Acetobacter indonesiensis UNPADCC 01–5 and Acetobacter senegalensis UNPADCC 02–8, exhibited strong inhibitory activity against A. flavus and Klebsiella pneumoniae. These findings highlight the potential of indigenous microbial consortia as natural biocontrol agents to improve the safety and standardization of traditional fermented foods.