Response of Sediment Microbial Communities to the Rural Wastewater in the Pond-Ditch Circulation System

Abstract

Microorganisms played important roles in nutrient removal in Pond-ditch circulation system (PDCS). However, dynamics of microbial community in the PDCS, and responses of rhizosphere and non-rhizosphere microbial community to rural wastewater remains unclear. In this paper, average operational taxonomic units numbers of sediment microbial varied from 10,254 to 17,112, and values in rhizosphere were higher than those of the non-rhizosphere (p < 0.05). Bacillus, Clostridium sensu stricto 1, and Geobacter were the predominant genera in PDCS sediment with relative abundances of 0.52–17.61%, 0.26–8.08%, and 0.20–4.58%, respectively. However, Bacillus, Clostridium sensu stricto 1, and Geobacter genera in rhizosphere were more abundant than those in non-rhizosphere at day 30. Chao 1 index ranged from 10,225 to 17,033 and showed significant positive correlations with all sediment properties (p < 0.05). Chao 1 and Shannon indices in rhizosphere were significant positively related to tartaric acid and total organic carbon, respectively; while significant correlation between Shannon and Simpson indices in non-rhizosphere and oxidation-reduction potential were detected (p < 0.05). Redundancy analysis suggested that lactic acids, proteins, and amino acids had strong positive effects on Geobacter and Clostridiu sensu stricto 12 in the rhizosphere; while Bacillus and Clostridium in non-rhizosphere were significantly affected by sediment ammonia nitrogen and nitrate nitrogen. Environmental variables accounted for 66.9 and 60.3% of the total variation for the microbial community of non-rhizosphere and rhizosphere sediments, respectively. Our results highlight that root exudates and sediment available N alter predominant genera in the rhizosphere and non-rhizosphere, respectively, which is benefit for optimizing removal efficiency of PDCSs in large-scale applications.

Microbial community diversity of an integrated constructed wetland used for treatment of sewage

“…As in phyla and classes, the diversity at the order level was also very high (188 orders) in the sediments which constituted 55.78% of the total orders recorded ( Table 3 ) suggesting that rhizospheric sediment microbiome is richer in diversity than non-rhizospheric sludge. Similar observations were made by Yu et al (2021) , who reported that complexity, composition, and structure of microbial community in rhizospheric sediment is higher than non rhizospheric sediments.…”

“…The top 5 most dominant phyla in the sludge were Proteobacteria (35.33%), Bacteroidetes (20.93%), Chloroflexi (8.51%), Planctomycetes (6.76%), and Acidobacteria (3.77%), but in the sediment the top 5 phyla include the first three phyla of sludge with different relative abundance values [ Proteobacteria (28.20%), Bacteroidetes (18.37%), Chloroflexi (11.17%)] and the 4th and 5th dominant phyla were Firmicutes (4.07%) in place of Planctomycetes and ODI (37.7%) instead of Acidobacteria , Verrucomicrobia (3.92%); and Planctomycetes (3.45%) occupy 6th and 7th positions, respectively in the sediment ( Supplementary Tables S1 , S2 ). Similar patterns of variation were reported by Yu et al (2021) , who reported that rhizospheric sediment had higher diversity than the non rhizospheric sediments. Rana et al (2023) also made similar observation relating to the diversity at phylum-level in microbial community of the Rhizospheric sediment of Typha latifolia .…”

“… Shanks et al (2013) also reported Chao I index values ranging from 2,332 to 3,196 for untreated waste waters collected from different locations in USA. Yu et al (2021) reported that rhizospheric sediments showed higher number of species 9,560–12,100 as compared to non-rhizospheric sediments; they also reported higher Chao I index (11,600–16,400), Shannon index (11.3–12.0) and Simpson index (0.9971–0.9979) for rhizospheric sediment in contrast to non rhizospheric sediment which showed ChaoI index ranging from 11,300 to 15,900, Shannon index ranging from 11.1 to 12.0 and Simpson index ranged from 0.9970 to 0.9977. Although Chao I index values reported by Yu et al (2021) are higher than the value obtained in the present study for rhizospheric sediment and sludge, but, the Shannon index value for the integrated CW is higher than the values reported by Yu et al (2021) .…”

“… Yu et al (2021) reported that rhizospheric sediments showed higher number of species 9,560–12,100 as compared to non-rhizospheric sediments; they also reported higher Chao I index (11,600–16,400), Shannon index (11.3–12.0) and Simpson index (0.9971–0.9979) for rhizospheric sediment in contrast to non rhizospheric sediment which showed ChaoI index ranging from 11,300 to 15,900, Shannon index ranging from 11.1 to 12.0 and Simpson index ranged from 0.9970 to 0.9977. Although Chao I index values reported by Yu et al (2021) are higher than the value obtained in the present study for rhizospheric sediment and sludge, but, the Shannon index value for the integrated CW is higher than the values reported by Yu et al (2021) . These differences and similarities in species indices of microbial communities of samples studied by different workers might be due to different plants used in CWs, quality of sewage, types of pollutants and other environmental conditions prevailing in CWs.…”

“… Weber (2016) reviewed the different methodologies used for assessment of microbial communities in CWs, particularly with respect to enumeration, structure, function and activity. Metagenomic studies of microbial communities of sludge from STPs, and rhizospheric sediment from stabilization ponds and CWs, using 16S rRNA gene sequencing have been carried out ( Gao et al, 2016 ; Yu et al, 2021 ). However, studies on microbial community diversity of the sludge from the stabilization pond and rhizospheric sediments of CW of the integrated CWS used for in situ bioremediation of sewage have not been done.…”