Streptomyces lunalinharesii strain 235 produces an antimicrobial substance that is active against sulfate reducing bacteria, the major bacterial group responsible for biofilm formation and biocorrosion in petroleum reservoirs. The use of this antimicrobial substance for sulfate reducing bacteria control is therefore a promising alternative to chemical biocides. In this study the antimicrobial substance did not interfere with the biofilm stability, but the sulfate reducing bacteria biofilm formation was six-fold smaller in carbon steel coupons treated with the antimicrobial substance when compared to the untreated control. A reduction in the most probable number counts of planktonic cells of sulfate reducing bacteria was observed after treatments with the sub-minimal inhibitory concentration, minimal inhibitory concentration, and supra-minimal inhibitory concentration of the antimicrobial substance. Additionally, when the treated coupons were analyzed by scanning electron microscopy, the biofilm formation was found to be substantially reduced when the supra-minimal inhibitory concentration of the antimicrobial substance was used. The coupons used for the biofilm formation had a small weight loss after antimicrobial substance treatment, but corrosion damage was not observed by scanning electron microscopy. The absence of the dsrA gene fragment in the scraped cell suspension after treatment with the supra-minimal inhibitory concentration of the antimicrobial substance suggests that Desulfovibrio alaskensis was not able to adhere to the coupons. This is the first report on an antimicrobial substance produced by Streptomyces active against sulfate reducing bacteria biofilm formation. The application of antimicrobial substance as a potential biocide for sulfate reducing bacteria growth control could be of great interest to the petroleum industry.

Sulphate-reducing bacteria (SRB) cause fouling, souring, corrosion and produce H2S during oil and gas production. Produced water obtained from Periquito (PQO) and Galo de Campina (GC) onshore oilfields in Brazil was investigated for SRB. Produced water with Postgate B, Postgate C and Baars media was incubated anaerobically for 20 days. DNA was extracted, 16S rDNA PCR amplified and fragments were sequenced using Illumina TruSeq. 4.2 million sequence reads were analysed and deposited at NCBI SAR accession number SRP149784. No significant differences in microbial community composition could be attributed to the different media but significant differences in the SRB were observed between the two oil fields. The dominant bacterial orders detected from both oilfields were Desulfovibrionales, Pseudomonadales and Enterobacteriales. The genus Pseudomonas was found predominantly in the GC oilfield and Pleomorphominas and Shewanella were features of the PQO oilfield. 11% and 7.6% of the sequences at GC and PQO were not classified at the genus level but could be partially identified at the order level. Relative abundances changed for Desulfovibrio from 29.8% at PQO to 16.1% at GC. Clostridium varied from 2.8% at PQO and 2.4% at GC. These data provide the first description of SRB from onshore produced water in Brazil and reinforce the importance of Desulfovibrionales, Pseudomonadales, and Enterobacteriales in produced water globally. Identifying potentially harmful microbes is an important first step in developing microbial solutions that prevent their proliferation.

Enrichment based isolation methods and molecular identification were used to investigate the microbial communities in produced water obtained from Periquito (PQO) and Galo de Campinas (GC) onshore oilfields in Brazil. Produced water was enriched with Postgate B, Postgate C and Baars media and incubated. DNA was extracted, PCR amplified and16S rDNA fragments were sequenced using Illumina TruSEq. 4.2 million reads were analysed and deposited at the Sequence Read Archive at NCBI. No significative differences in microbial community composition could be attributed to the enrichment but significant differences were observed from two oil fields. The dominant Bacterial Orders detected from both oilfields were Desulfovibrionales, Pseudomonadales and Enterobacteriales. Pseudomonas were found predominantly in Periquito oilfield (19.8%) with only 2,4% at Galo de Campinas. Pleomorphominas (3.76%) and Shewanella (4,69%) were exclusive to and possible biomarkers for the Periquito Oilfield. 11.05% and 7.62% of the sequences were not classified at genus level and detected at GC and P. Abundances changed for Desulfovibrio from P, 29.8% at PQO and 16.08% at GC. The Clostridium_sensu_stricto varied from 2.8% at PQO and 2.4% at GC). Pseudomonas were found predominantly in Periquito oilfield (19.8%) with only 2,4% at Galo de Campinas. Pleomorphominas (3.76%) and Shewanella (4,69%) were almost exclusive to and possible biomarkers for the Periquito Oilfield. These data provide a bacterial biodiversity benchmark for future produced water treatment and microbially enhanced oil recovery (MEOR).