Inhibitory spectrum of diverse guaiacol-producing Alicyclobacillus acidoterrestris by poly dimethyl ammonium chloride disinfectant

Abstract

Alicyclobacillus acidoterrestris is a soil-borne, thermo-acidophilic, endospore-forming bacterium which causes the spoilage of pasteurized fruit juices with the production of guaiacol taints. In this study the antimicrobial activity of poly dimethyl ammonium chloride (PDAC), an emerging disinfectant, against A. acidoterrestris was investigated. Initially, four bacteria isolates obtained from orchard soils were identified as A. acidoterrestris by 16S ribosomal RNA (rRNA) gene sequencing followed by analysis of random amplified polymorphic DNA (RAPD) fragments, which grouped the isolates into two genotypes. High performance liquid chromatographic (HPLC) analysis revealed the activity of vanillic-acid decarboxylase (vdc) in the A. acidoterrestris strains, as measured by the production of guaiacol from vanillic acid (VA), indicating the isolates’ spoilage potential. Subsequently, representative strains from the two RAPD types of A. acidoterrestris were treated with PDAC. Disc diffusion assay on YSG agar revealed that A. acidoterrestris strains ULAG14, ULAG15 and the type strain DSM 3922T were sensitive to PDAC at concentrations ranging from 0.5% to 20% and inhibition of endospore germination was observed after 5 min exposure. PDAC has an inhibitory effect against the vegetative cells and endospores of A. acidoterrestris under laboratory conditions; it may be potentially useful for industrial application in cleaning of fruits and production surfaces for quality control during the processing of tropical fruit juices.