Effects of two diamine biocides on the microbial community from an oil field

Abstract

The effects of diamine (R 1 -NH-R 2 -NH 2 ) biocides A and B on the microbial population from an oil field were investigated with reverse sample genome probing (RSGP), a technique designed to track multiple oil field bacteria in a single assay. RSGP studies of sessile microbial populations scraped from corrosion coupons obtained from biocide-treated oil field installations indicated dominance of Desulfovibrio spp. Lac6 and Eth3, or of selected heterotrophs. RSGP of planktonic production water samples indicated a broad distribution of microorganisms that changed with the addition of medium for the growth of sulfate-reducing bacteria, containing different organic acids as electron donors for sulfate reduction. Use of lactate, propionate, or acetate enriched Desulfovibrio spp., Desulfobulbus sp. Pro4, or Desulfobacter spp., respectively. Treatment of lactate- or mixed organic acid-fed planktonic populations with biocides indicated resistance of Lac6 and Eth3 to 400 ppm of biocide B and 40 ppm of biocide A. The dominance of these two Desulfovibrio spp. in many sessile field samples is, therefore, likely caused by biocide selection.Key words: Desulfovibrio, sulfate reduction, microbial corrosion, souring, biocide.