Microtitre Plate Assay for Biofilm Formation, Production and Utilization of Hydroxybiphenyl by Rhodococcus sp. Isolated from Gasoline-Contaminated Soil

Abstract

Gasoline-contaminated soil from Isfahan, Iran was selected to isolate a bacterium capable of desulfurizing dibenzothiophene (DBT). The isolated strain was named R1 and identified as Rhodococcus erythropolis through biochemical tests as well as sequencing of 16S rRNA gene. This strain could efficiently produce 2-hydroxybiphenyl (HBP) from DBT via the 4S metabolic pathway. The highest HBP amount was produced at 2 mm DBT with addition of glucose (10 g l Ð1 ), ethanol (3 g l Ð1 ), glycerol (2 g l Ð1 ) or succinate (10 g l Ð1 ) as carbon sources at pH 7. Highest respiration and growth rates were observed by microplate titration on 0.1 mm HBP, and addition of 0.2 mm HBP to glucose (1 g l Ð1 ) and DBT (0.3 mm) could inhibite the respiration of the isolate. The isolated strain could grow up to 0.4 mm of HBP when it is used with mineral sulfur as sole sulfur source. To the best of our knowledge this is the first report on a microtiter assay for the production and utilization of HBP by Rhodococcus.

Isolation and classification of a soil actinomycete capable of sulphur-specific biotransformation of dibenzothiophene, benzothiophene and thianthrene

“…However, another study reported the growth of Rhodococcus sp. in the presence of up to 0·4 mmol l −1 HBP with mineral sulphur as the sulphur source (Etemadifar and Emtiazi ).…”

Proteus mirabilis biofilm - Qualitative and quantitative colorimetric methods-based evaluation

“…Korenová et al (2008) results highlighted also CV-based method tendency to overrate biofilm formation level by bacterial strains producing extracellular polysaccharides as a disadvantage but on the other hand advantages of its high reproducibility due to application in many laboratories worldwide, low cost of the dye and rather common instruments for the results read-out. This technique belongs to one of the most popular ( Ali, 2012 ; Balasubramanian et al , 2012 ; Esteban et al , 2010 ; Etemadifar and Emtiazi, 2008 ; Hassan et al , 2011 ; Khan et al , 2011 ; Wasfi et al , 2012 ) and is considered highly optimized. The quantitative method described by Christensen et al (1985) is believed as gold standard amongst other biofilm detection methods.…”

“…On the contrary, quantitative method applying TTC is not so common. Except Mahdavi et al (2007) it was used by Etemadifar and Emtiazi (2008) work for dehydrogenase activity evaluation for Rhodococcus spp . R1 derived from petrol-polluted soil.…”