The Effect of Grown Cell and Cell Free Extract of Rhodococcus sp. and Paenibacillus sp. on Dimethyl Disulfide (DMDS) and Diethyl Disulfide (DEDS) Removal

For first time, biodegradation of Dimethyl Disulfide (DMDS) and Diethyl Disulfide (DEDS) were studied by several bacterial strains, isolated from experimental biofilter filled with these compounds. Among the isolates, two strains identified as Paenibacillus and Rhodococcus could utilize DEDS up to 80.4% when they were grown on glycerol during 10 days while induced cell free extract of Rhodococcus could remove this compound by 58% in 30'. Using of DEDS (2 ml l −1 ) as the sole sulfur source delayed lag phase of Paenibacillus growth for 3 days, when this strain was cultivated on screw capped Castaneda bottles, but growth rate was the same as control. Addition of DMDS (2 ml l −1 ) reduced the growth rate of both strains; however, Paenibacillus and Rhodococcus could utilize this substrate up to 28.8%. None of these isolates could use DMDS or DEDS as the sole carbon sources. Microplate titer assay showed that using high concentration of DMDS (5 ml l −1 ) and DEDS (5 ml l −1 ) did not have positive effect on growth in aerobic condition. However, low concentration of DEDS (5mM) in the same condition increased the growth rate of both strains.