The presence of in situ sulphamethoxazole degraders and their interactions with other microbes in activated sludge as revealed by DNA stable isotope probing and molecular ecological network analysis

ABSTRACT The acetate-utilizing microbial consortium in a full-scale activated sludge process was investigated without prior enrichment using stable isotope probing (SIP). [13C]acetate was used in SIP to label the DNA of the denitrifiers. The [13C]DNA fraction that was extracted was subjected to a full-cycle rRNA analysis. The dominant 16S rRNA gene phylotypes in the 13C library were closely related to the bacterial families Comamonadaceae and Rhodocyclaceae in the class Betaproteobacteria. Seven oligonucleotide probes for use in fluorescent in situ hybridization (FISH) were designed to specifically target these clones. Application of these probes to the sludge of a continuously fed denitrifying sequencing batch reactor (CFDSBR) operated for 16 days revealed that there was a significant positive correlation between the CFDSBR denitrification rate and the relative abundance of all probe-targeted bacteria in the CFDSBR community. FISH-microautoradiography demonstrated that the DEN581 and DEN124 probe-targeted cells that dominated the CFDSBR were capable of taking up [14C]acetate under anoxic conditions. Initially, DEN444 and DEN1454 probe-targeted bacteria also dominated the CFDSBR biomass, but eventually DEN581 and DEN124 probe-targeted bacteria were the dominant bacterial groups. All probe-targeted bacteria assessed in this study were denitrifiers capable of utilizing acetate as a source of carbon. The rapid increase in the number of organisms positively correlated with the immediate increase in denitrification rates observed by plant operators when acetate is used as an external source of carbon to enhance denitrification. We suggest that the impact of bacteria on activated sludge subjected to intermittent acetate supplementation should be assessed prior to the widespread use of acetate in the wastewater industry to enhance denitrification.

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Combining stable isotope enrichment, compartmental modelling and ecological network analysis for quantitative measurement of food web dynamics

Methods in Ecology and Evolution ◽

10.1111/j.2041-210x.2010.00045.x ◽

2010 ◽

Vol 2 (1) ◽

pp. 56-65 ◽

Cited By ~ 12

Author(s):

Ka-Man Lee ◽

Shing Yip Lee ◽

Rod M. Connolly

Keyword(s):

Network Analysis ◽

Stable Isotope ◽

Food Web ◽

Quantitative Measurement ◽

Isotope Enrichment ◽

Ecological Network ◽

Compartmental Modelling ◽

Ecological Network Analysis ◽

Food Web Dynamics ◽

Stable Isotope Enrichment

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Comparison of soil microbial community between reseeding grassland and natural grassland in Songnen Meadow

Scientific Reports ◽

10.1038/s41598-020-74023-x ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Ruifen Zhu ◽

Jielin Liu ◽

Jianli Wang ◽

Weibo Han ◽

Zhongbao Shen ◽

...

Keyword(s):

Microbial Community ◽

Network Analysis ◽

Soil Microbial Community ◽

Vegetation Restoration ◽

Ecological Network ◽

Soil Microbial Community Structure ◽

Ecological Network Analysis ◽

Soil Microbial ◽

Natural Grassland ◽

Molecular Ecological Network

Abstract Microorganisms have important ecological functions in ecosystems. Reseeding is considered as one of the main strategies for preventing grassland degradation in China. However, the response of soil microbial community and diversity to reseeding grassland (RG) and natural grassland (NG) remains unclear, especially in the Songnen Meadow. In this study, the soil microbial community compositions of two vegetation restoration types (RG vs NG) were analyzed using a high-throughput sequencing technique. A total of 23,142 microbial OTUs were detected, phylogenetically derived from 11 known bacterial phyla. Soil advantage categories included Proteobacteria, Acidobacteria, Actinobacteria, and Bacteroidetes, which together accounted for > 78% of the all phyla in vegetation restoration. The soil microbial diversity was higher in RG than in NG. Two types of vegetation restoration had significantly different characteristics of soil microbial community (P < 0.001). Based on a molecular ecological network analysis, we found that the network in RG had a longer average path distance and modularity than in NG network, making it more resilient to environment changes. Meanwhile, the results of the canonical correspondence analysis and molecular ecological network analysis showed that soil pH (6.34 ± 0.35 in RG and 7.26 ± 0.28 in NG) was the main factor affecting soil microbial community structure, followed by soil moisture (SM) in the Songnen meadow, China. Besides, soil microbial community characteristics can vary significantly in different vegetation restoration. Thus, we suggested that it was necessary and reasonable for this area to popularize reseeding grassland in the future.

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