Simultaneous biodegradation of dimethyl sulfide and 1-propanethiol by Pseudomonas putida S-1 and Alcaligenes sp. SY1: “Lag” cause, reduction, and kinetics exploration

Abstract

Simultaneous biodegradation of malodorous 1-propanethiol (PT) and dimethyl sul de (DMS) inoculated with Pseudomonas putida S-1 and Alcaligenes sp. SY1 were investigated and interactions implicated were explored. Results showed that PT was completely degraded in 33 h, while a lag of 10 h was observed for DMS degradation alone, and the lag even extended to 81 h in the binary mixture. Mechanism analysis found that the lag was mainly attributed to the exposure of DMS degrader (Alcaligenes sp. SY1), rather than PT metabolites and PT degrader. The exposure time and PT concentration in uenced the lag duration much. Citric acid could effectively reduce the lag. Pseudo rst-order model was proved suitable for the description of PT degradation, revealing that PT degradation could be enhanced in presence of DMS regardless of its concentration. A modi ed Gompertz model, incorporated the lag phase, was developed for the description of DMS degradation in the mixture, revealing that DMS degradation depended on the initial PT concentration. When the lag was not considered, PT with low-concentration could promote DMS biodegradation, while a higher concentration ( 20 mg•L −1 ) cast negative effect. IntroductionVolatile organic compounds (VOCs) are widely considered as major precursors for the photochemical smog and haze, imposing great threats on environment quality and human health. As a typical kind of VOCs, volatile organic sulfur compounds (VOSCs) are highly toxic and malodorous with extremely low smell threshold, (Padhi and Gokhale 2017). They are not only the main composition of traditional malodor sources, i.e. waste water treatment plants, waste land lls, livestock and poultry farm etc., but also closely related with pharmaceutical chemicals, petroleum re neries, papermaking and other industries (Giri and Pandey 2013;Giri et al. 2014). So far, many treatment technologies, like condensation, UV oxidation, regenerative thermal oxidization, catalytically incineration, adsorption etc., have been employed for the disposal of odorous and hazardous organic compounds (Durme et al. 2008;Zhang et al. 2017). Thereinto, biotechnology is one of the most applicable ways for the puri cation of VOSCs, due to its various advantages of ecological, low cost and no secondary pollution etc., especially for the waste gas with high-volume and low-concentration (Jo and Shin 2010; Qiu and Deshusses 2017; Kennes and Veiga 2013).To date, numerous microorganisms have been acclimated and isolated for the degradation of VOSCs.These microorganisms are usually highly speci c, only one or one kind of VOSC compounds can be e ciently degraded. However, multiple waste gases usually coexist in practical situations. Unknown interactions are likely to occur during their degradation processes, which may largely in uence their original degradation behaviors. It was reported that the removal of dimethyl sul de (DMS) and dimethyl disul de were affected by the presence of methyl mercaptan and H 2