Influence of surfaces on sulphidogenic bacteria

Abstract

Sulphidogenic bacteria in oil reservoirs are of great economic importance in terms of souring, fouling and corrosion. Mixed cultures containing these bacteria were isolated from chalk formations in North Sea oil reservoirs. These were thermophilic cultures, growing optimally at 60°C. Oil formations are porous matrices, providing a very large surface area and ideal conditions for bacterial attachment, survival and growth. This study included assessments of sulphide production rates of thermophilic (t-)sulphidogen consortia with and without additional surfaces. The availability of a surface contributed significantly to the rate and extent of sulphide generation. Surfaces were offered in varying amounts to growing planktonic cultures: significantly more sulphide was produced from cultures in contact with a surface than from identical cultures in the absence of a surface. In another series of experiments, t-sulphidogens were added to chalk rock chips in the presence of nutrients and incubated for several months. This resulted in rapid sulphide generation, the final concentration being related to the initial nutrient concentration. Subsequent nutrient addition resulted in renewed sulphide generation. It is suggested that bacteria in reservoirs can withstand long periods of nutrient deprivation while attached within the porous rock matrix and opportunistically utilise nutrients when they become available.

Biological removal of sulfurous compounds and metals from inorganic wastewaters

“…Another factor that has been observed to affect the growth and activity of SRB is the availability of suitable surfaces for bacterial attachment and colonization (e.g. Bass et al, 1996).…”

Long‐term starvation survival of a thermophilic sulfidogen consortium

“…We demonstrated the ability of a sessile community of consortium EX251 attached to reservoir rock (chalk chips) to survive and recommence sulfide generation after 7 months of carbon source deprivation (Bass et al 1996). Walsh (1996) demonstrated that tSRB species are recoverable from open seawater.…”

“…The consortium was enriched and maintained in EX2 medium (Bass et al 1996). Seawater medium (SWM) was prepared by dissolving sodium pyruvate and Oxoid yeast extract (6.0 and 1.0 g L" 1 , respectively) in deaerated artificial seawater (ASW, prepared by dissolving 33.0 g Lr 1 Tropic Marin Aquarientechnik, Wartenburg, Germany in distilled water); pH was adjusted to 6.5.…”

Enrichment and characterisation of sulfate-reducing bacteria from sandstone rock cores from the UK Continental shelf

“…The novel opportunity of examining fresh hydrocarbon formation rock core from the UKCS has allowed the first report of the enrichment and initial characterisation of a thermophilic community of SRB. These subsurface environments are prone to bacterial growth and H 2 S production but until this study it was only possible to enrich for the causative SRB from produced waters [3, 14, 17]. It is extremely difficult to take geological specimens and make definitive statements concerning the presence of microorganisms on their surfaces [20].…”

“…Crushed inner core was inoculated into vials containing a pyruvate‐based SRB growth medium denoted EX2 [17]and a modification of Postgate's medium C [18]by the replacement lactate with pyruvate, denoted PCP. The medium was prepared anaerobically as described previously [17].…”