Cath, T. Y. | Search bioRxiv

bioRxiv2023

Iodidimonas, a bacterium unable to degrade hydrocarbons, thrives in a bioreactor treating oil and gas produced water

Iodidimonas is a genus recently described in bioreactors treating oil and gas produced water and in iodide rich brines. Besides the ability to oxidize iodine, little is known about the metabolic capabilities that enable Iodidimonas sp. to occupy this unique ecological niche. We isolated, characterized, and sequenced three strains belonging to the Iodidimonas genus from the sludge of a membrane bioreactor treating produced water. We describe the genomic features of these isolates and compare them with the only other four isolate genomes reported from this genus, as well as a metagenome-assembled genome from the source bioreactor. To survive in the produced water, Iodidimonas isolates had several genes associated with mitigating salinity, heavy metal and organic compound stress. While the isolates could utilize a wide variety of carbon substrates, they failed to degrade aliphatic or aromatic hydrocarbons, consistent with the lack of genes associated with common hydrocarbon degradation pathways in their genomes. We hypothesize these microbes may lead a scavenging lifestyle in the bioreactor and similar iodide-rich brines. ImportanceOccupying a niche habitat and having few representative isolates, genus Iodidimonas is a relatively understudied Alphaproteobacterial group. This genus has garnered attention due to its ability to corrode pipes in iodine production facilities and generate iodinated organic compounds during treatment of oil and gas produced water. The iodinated organic compounds are likely to be carcinogenic and may pose issues with recycling the treated water. Hence, detailed characterization of the metabolic potential of these isolates is not only of economic importance, but also sheds light on adaptation of this microbe to its environmental niche.

ecology↗

bioRxiv2020

Microbially-mediated pretreatment of aerated oil and gas produced water by addition of phosphorous or activated sludge

Produced Water (PW) from oil and gas (O&G) producing wells is a unique source of water in water-stressed regions. Microbiota within O&G formations have been well-studied on site/in-situ, but few applied works have considered their role in the treatment of PW in engineered water treatment systems. Herein, we operated a simple aeration/mixing bench-scale bioreactor fed with produced water under three conditions: 1) PW alone (control; hereafter referred to as baseline), 2) phosphorous dosed daily as KH2PO4, and 3) activated sludge (AS) dosed daily from a sequence batch membrane bioreactor (SB-MBR). Aerated and mixed PW alone (baseline) was able to attenuate PW chemistry with removal of soluble chemical oxygen demand (sCOD) and ammonia by 27.6% and 17.8%, respectively. Further KH2PO4 and AS additions improved water treatment efficiency markedly; in the KH2PO4 addition reactor, sCOD and ammonia were reduced by 50.0% and 61.5%, respectively, and in the AS addition reactor by 52.5% and 59.2%, respectively. Microbial consortia determined via 16S rRNA gene amplicons differ in composition between raw PW and all reactors; order Kiloniellales was most common in raw PW while orders Rhodobacterales, Pseudomonadales, and Caulobacterales were most abundant amongst AS, KH2PO4, and baseline conditions, respectively. Several different microbial consortia are capable of treating raw PW which suggests that functional redundancy amongst microbiota in engineered treatment systems may be underappreciated. With simple addition of phosphorous and/or activated sludge to PW as part of a treatment strategy, a higher quality water can then be subjected to conventional treatment and/or local reuse. ImportanceMultiple microbiological communities are capable of treating O&G PW in a simple, applied, engineered setting. The broad possibility of PW treatment by multiple different microbial consortia elucidates the potential for easy, effective, water reuse processes in the hydraulically-stressed arid west as well as any region generating PW from O&G operations.

microbiology↗