Stratification of microbial communities throughout a biological sulphate reducing up-flow anaerobic packed bed reactor, revealed through 16S metagenomics

Syntrophic H2 production enhances the performance of primarily acetate-supplemented reactors treating sulphate contaminated solutions

“…Stratification of the microbial communities between the successive zones of the lactate-supplemented UAPBR occurred due to the plug-flow fluid dynamics that govern this reactor configuration (Figure S3). The performance of this system is summarised in Figure 5B and has been previously reported by Hessler et al (2018). Briefly, the sulfate consumed within this reactor decreased between each subsequent reactor zone, from approximately 6.0 mM in the inlet zone to 0.6 mM in the effluent zone.…”

“…The observed sulfate reduction was putatively linked to the oxidation of various quantified VFAs. Some of these reactor performance data have been previously reported (Hessler et al, 2018(Hessler et al, , 2020 and can be found in the supplementary data (Table S1). Duplicate samples were taken from the acetate-and the lactate-supplemented CSTRs for metagenomic analysis.…”

“…The high sulphate conversions achieved by the lactate amended UAPBR was previously attributed to the out-competition of fermentative microorganisms for lactate by SRB in the inlet zone, and secondly the zoning of the reactor allowing different SRB suited to the oxidation of different electron donors to effectively compete in niche environments along the length of the reactor (Hessler et al, 2018). What was not considered in previous analyses was the effect of hydrogen produced during fermentation of lactate, yeast extract and citrate in the inlet zone, on the growth of SRB present in the middle and effluent zones.…”

“…The six reactor systems were inoculated with a mixed sulfidogenic microbial culture described by Hessler et al (2018). This microbial culture was maintained, prior to inoculation, on neutral modified Postgate B medium (0.42 g/L KH2PO4, 1.0 g/L NH4Cl, 1.0 g/L MgSO4.7H2O, 0.9 g/L Na2SO4, 0.4 g/L yeast extract, 0.3 g/L sodium citrate) supplemented with various electron donors including acetate, lactate, ethanol and algal anaerobic digestate.…”

“…Each of these reactor systems was operated in duplicate and continuously fed the modified postgate B medium supplemented with either sodium acetate (0.92 g/L) or sodium lactate (1.2 g/L) as the electron donor. The CSTR and UAPBR configurations are described by Hessler et al (2018) and the LFCR is described by Hessler et al (2020a).…”