Panwajee Payongsri, Nattapat Charoenrat, Thunyarat Pongtharangkul, and Jirarut Wongkongkatep

DOI: 10.14456/sjst-psu.2020.152

pp. 1164 - 1170

Abstract

The bioconversion of water-immiscible chemicals by microbes may occur through viable but nonculturable cells
(VBNC) and the evaluation of such cellular activity is important for a deeper understanding of the metabolic process. In this
study, the metabolic CO₂ production in a bacteria interface emulsion, consisting of bacteria, chitosan and solvent, has been
monitored using headspace gas chromatography (GC) and indirect conductivity (IC). The results from GC in comparison to the
standard culture technique revealed the presence of VBNC state when _{E. coli} DH5α and P. putida F1 were in contact with n-hexane. L. lactis IO-1 was the most sensitive strain, but the VBNC cells were obvious in the case of soybean and n-decane.
Although GC showed better detection sensitivity, the IC technique was more practical and cost-effective. Therefore, GC and IC
could be extremely simple and useful methods for monitoring the VBNC state of bacteria, which generally stems from
environmental stresses.