Occurrence and Succession of Bacterial Community in O3/BAC Process of Drinking Water Treatment

Temporal patterns of bacterial communities in the Billings Reservoir system

In this study, high-throughput sequencing of 16S rRNA amplicons and predictive PICRUSt functional profiles were used to perform a comprehensive analysis of the temporal bacterial distribution and metabolic functions of 19 bimonthly samples collected from July 2019 to January 2020 in the surface water of Billings Reservoir, São Paulo. The results revealed that most of the bacterial 16S rRNA gene sequences belonged to Cyanobacteria and Proteobacteria, which accounted for more than 58% of the total bacterial abundance. Species richness and evenness indices were highest in surface water from summer samples (January 2020), followed by winter (July 2019) and spring samples (September and November 2019). Results also showed that the highest concentrations of sulfate (SO4-2), phosphate (P), ammonia (NH3), and nitrate (NO3-) were detected in November 2019 and January 2020 compared with samples collected in July and September 2019 (P < 0.05). Principal component analysis suggests that physicochemical factors such as pH, DO, temperature, and NH3 are the most important environmental factors influencing spatial and temporal variations in the community structure of bacterioplankton. At the genus level, 18.3% and 9.9% of OTUs in the July and September 2019 samples, respectively, were assigned to Planktothrix, while 14.4% and 20% of OTUs in the November 2019 and January 2020 samples, respectively, were assigned to Microcystis. In addition, PICRUSt metabolic analysis revealed increasing enrichment of genes in surface water associated with multiple metabolic processes rather than a single regulatory mechanism. This is the first study to examine the temporal dynamics of bacterioplankton and its function in Billings Reservoir during the winter, spring, and summer seasons. The study provides comprehensive reference information on the effects of an artificial habitat on the bacterioplankton community that can be used to interpret the results of studies to evaluate and set appropriate treatment targets.

Proteogenomic analysis of Georgfuchsia toluolica revealed unexpected concurrent aerobic and anaerobic toluene degradation

Denitrifying Betaproteobacteria play a key role in the anaerobic degradation of monoaromatic hydrocarbons. We performed a multi-omics study to better understand the metabolism of the representative organism Georgfuchsia toluolica strain G5G6 known as a strict anaerobe coupling toluene oxidation with dissimilatory nitrate and Fe(III) reduction. Despite the genomic potential for degradation of different carbon sources, we did not find sugar or organic acid transporters, in line with the inability of strain G5G6 to use these substrates. Using a proteomics analysis, we detected proteins of fumarate-dependent toluene activation, membrane-bound nitrate reductase, and key components of the metal-reducing (Mtr) pathway under both nitrate- and Fe(III)-reducing conditions. High abundance of the multiheme cytochrome MtrC implied that a porin-cytochrome complex was used for respiratory Fe(III) reduction. Remarkably, strain G5G6 contains a full set of genes for aerobic toluene degradation, and we detected enzymes of aerobic toluene degradation under both nitrate- and Fe(III)-reducing conditions. We further detected an ATP-dependent benzoyl-CoA reductase, reactive oxygen species detoxification proteins, and cytochrome c oxidase indicating a facultative anaerobic lifestyle of strain G5G6. Correspondingly, we found diffusion through the septa a substantial source of oxygen in the cultures enabling concurrent aerobic and anaerobic toluene degradation by strain G5G6.

Spatial-Temporal Variation of Bacterial Communities in Sediments in Lake Chaohu, a Large, Shallow Eutrophic Lake in China

Sediment bacterial communities are critical for the circulation of nutrients in lake ecosystems. However, the bacterial community function and co-occurrence models of lakes have not been studied in depth. In this study, we observed significant seasonal changes and non-significant spatial changes in the beta diversity and community structure of sediment bacteria in Lake Chaohu. Through linear discriminant analysis effect size (LEfSe), we observed that certain taxa (from phylum to genus) have consistent enrichment between seasons. The sudden appearance of a Firmicutes population in spring samples from the Zhaohe River, an estuary of Lake Chaohu, and the dominance of Firmicutes populations in other regions suggested that exogenous pollution and environmental induction strongly impacted the assembly of bacterial communities in the sediments. Several taxa that serve as intermediate centers in Co-occurrence network analysis (i.e., Pedosphaeraceae, Phycisphaeraceae, Anaerolineaceae, and Geobacteraceae) may play an important role in sediments. Furthermore, compared with previous studies of plants and animals, the results of our study suggest that various organisms, including microorganisms, are resistant to environmental changes and/or exogenous invasions, allowing them to maintain their community structure.