scholarly journals Comparative Analysis of Bacterial and Archaeal Community Structure in Microwave Pretreated Thermophilic and Mesophilic Anaerobic Digesters Utilizing Mixed Sludge under Organic Overloading

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 887 ◽  
Author(s):  
Gokce Kor-Bicakci ◽  
Emine Ubay-Cokgor ◽  
Cigdem Eskicioglu

The effects of microwave (MW) pretreatment were investigated by six anaerobic digesters operated under thermophilic and mesophilic conditions at high organic loading rates (4.9–5.7 g volatile solids/L/d). The experiments and analyses were mainly designed to reveal the impact of MW pretreatment and digester temperatures on the process stability and microbial community structure by correlating the composition of microbial populations with volatile fatty acid (VFA) concentrations. A slight shift from biogas production (with a reasonable methane content) to VFA accumulation was observed in the thermophilic digesters, especially in the MW-irradiated reactors. Microbial population structure was assessed using a high-throughput sequencing of 16S rRNA gene on the MiSeq platform. Microbial community structure was slightly affected by different MW pretreatment conditions, while substantially affected by the digester temperature. The phylum Bacteroidetes proliferated in the MW-irradiated mesophilic digesters by resisting high-temperature MW (at 160 °C). Hydrogenotrophic methanogenesis (mostly the genus of Methanothermobacter) was found to be a key route of methane production in the thermophilic digesters, whereas aceticlastic methanogenesis (mostly the genus of Methanosaeta) was the main pathway in the mesophilic digesters.

Author(s):  
Yong Li ◽  
Jiejie Zhang ◽  
Jianqiang Zhang ◽  
Wenlai Xu ◽  
Zishen Mou

To study the microbial community structure in sediments and its relation to eutrophication environment factors, the sediments and the overlying water of Sancha Lake were collected in the four seasons. MiSeq high-throughput sequencing was conducted for the V3–V4 hypervariable regions of the 16S rRNA gene and was used to analyze the microbial community structure in sediments. Pearson correlation and redundancy analysis (RDA) were conducted to determine the relation between microbial populations and eutrophic factors. The results demonstrated four main patterns: (1) in the 36 samples that were collected, the classification annotation suggested 64 phyla, 259 classes, 476 orders, 759 families, and 9325 OTUs; (2) The diversity indices were ordered according to their values as with summer > winter > autumn > spring; (3) The microbial populations in the four seasons belonged to two distinct characteristic groups; (4) pH, dissolved oxygen (DO), total phosphorus (TP), and total nitrogen (TN) had significant effects on the community composition and structure, which further affected the dissolved total phosphorus (DTP) significantly. The present study demonstrates that the microbial communities in Sancha Lake sediments are highly diverse, their compositions and distributions are significantly different between spring and non-spring, and Actinobacteria and Cyanobacteria may be the key populations or indicator organisms for eutrophication.


Elem Sci Anth ◽  
2019 ◽  
Vol 7 ◽  
Author(s):  
Sahra J. Webb ◽  
Tia Rabsatt ◽  
Natalia Erazo ◽  
Jeff S. Bowman

Marine eelgrasses are influential to their surrounding environments through their many ecosystem services, ranging from the provisioning of food and shelter for marine life to serving as a natural defense against pollution and pathogenic bacteria. In the marine waters of San Diego, CA, USA, eelgrass beds comprised of Zostera spp. are an integral part of the coastal ecosystem. To evaluate the impact of eelgrass on bacterial and archaeal community structure we collected water samples in San Diego Bay and sequenced the 16S rRNA gene from paired eelgrass-present and eelgrass-absent sites. To test the hypothesis that microbial community structure is influenced by the presence of eelgrass we applied mixed effects models to these data and to bacterial abundance data derived by flow cytometry. This approach allowed us to identify specific microbial taxa that were differentially present at eelgrass-present and eelgrass-absent sites. Principal coordinate analysis organized the samples by location (inner vs. outer bay) along the first axis, where the first two axes accounted for a 90.8% of the variance in microbial community structure among the samples. Differentially present bacterial taxa included members of the order Rickettsiales, family Flavobacteriaceae, genus Tenacibaculum and members of the order Pseudomonadales. These findings constitute a unique look into the microbial composition of San Diego Bay and examine how eelgrasses contribute to marine ecosystem health, e.g., by supporting specific microbial communities and by filtering and trapping potentially harmful bacteria to the benefit of marine organisms.


2017 ◽  
Vol 83 (12) ◽  
Author(s):  
Anna Neubeck ◽  
Li Sun ◽  
Bettina Müller ◽  
Magnus Ivarsson ◽  
Hakan Hosgörmez ◽  
...  

ABSTRACT The surface waters at the ultramafic ophiolitic outcrop in Chimaera, Turkey, are characterized by high pH values and high metal levels due to the percolation of fluids through areas of active serpentinization. We describe the influence of the liquid chemistry, mineralogy, and H2 and CH4 levels on the bacterial community structure in a semidry, exposed, ultramafic environment. The bacterial and archaeal community structures were monitored using Illumina sequencing targeting the 16S rRNA gene. At all sampling points, four phyla, Proteobacteria, Actinobacteria, Chloroflexi, and Acidobacteria, accounted for the majority of taxa. Members of the Chloroflexi phylum dominated low-diversity sites, whereas Proteobacteria dominated high-diversity sites. Methane, nitrogen, iron, and hydrogen oxidizers were detected as well as archaea and metal-resistant bacteria. IMPORTANCE Our study is a comprehensive microbial investigation of the Chimaera ophiolite. DNA has been extracted from 16 sites in the area and has been studied from microbial and geochemical points of view. We describe a microbial community structure that is dependent on terrestrial, serpentinization-driven abiotic H2, which is poorly studied due to the rarity of these environments on Earth.


2021 ◽  
Author(s):  
Mohsin Gulzar Barq ◽  
Muhammad Mabashar Hassan ◽  
Nicola Lorenz ◽  
Noshaba Hassan Malik ◽  
Richard Dick ◽  
...  

Abstract The impact of environmental perturbations (e.g., nitrogen (N), phosphorus (P), potassium (K) and rice straw (Rs)) on the dynamics of soil bacterial and archaeal community are multifactor dependent and seeks more investigation concerning underlying mechanisms. Current study was designed to establish the effect of pure and mixed fertilizers on microbial community profiles in paddy soil. A short-term microcosm based experiment was established in which each microcosm is amended with N as C(H2N)2O, P and K as KH2PO4, K as KCl and Rs with concentrations equivalent to 160 kg N ha−1, 60 kg P ha−1, 130 kg K ha−1 and 1% respectively. Soil pH, electrical conductivity (EC), total C (TC), total nitrogen (TN), organic matter (OM), available K (AK) and extractable P (EP) were evaluated. To understand the microbial community variation in soil and to predict their metabolic functions, a high throughput sequencing (HTS) approach of 16S rRNA gene along with phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) was employed and analyzed. The results showed that microbial richness and diversity were increased under all amendments compared to control. Proteobacteria, Actinobacteria and Firmicutes were dominant bacterial phyla. In all amendments, regarding relative abundance, Chloroflexi, Bacteroidetes and Verrucomicrobia showed positive while Actinobacteria, Acidobacteria and Gemmatimonadetes showed negative trends when compared with controlled observations. Thaumarchaeota and Euryarchaeota were dominant archaeal phyla and exhibited increasing and decreasing trends, respectively. The PICRUSt indicated microbial community shift significantly towards amino acid, carbohydrate, energy, and lipid metabolism while less towards glycan biosynthesis, synthesis of secondary metabolites, terpenoids and biodegradation. Regarding metabolism (methane metabolism), most and least responsive treatments were predicted to be KP and controls, respectively. These findings enhanced our understanding regarding soil quality, fertilizer composition and their impact on microbial diversity.


2021 ◽  
Author(s):  
Yanbo Liu ◽  
Mengxiao Sun ◽  
Pei Hou ◽  
Wenya Wang ◽  
Xiangkun Shen ◽  
...  

Abstract In this study, the pit mud used in manufacturing Taorong-type Baijiu was collected from the upper, middle, lower and bottom layers of pits in Henan Yangshao Liquor Co., LTD. Besides, high-throughput sequencing (HTS) technology was adopted to analyze the microbial community structure of the pit mud. In addition, the volatile compounds in the pit mud were subjected to preliminarily qualitative analysis through headspace-solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The results of HTS demonstrated that there were 5, 3, 5 and 5 dominant bacterial phyla (including 11, 11, 9 and 8 dominant bacterial genera) and 3, 3, 3 and 3 dominant fungal phyla (including 4, 7, 7 and 5 dominant fungal genera) in the pit mud from F-S (upper), G-Z (middle), H-X (lower) and I-D (bottom), respectively. The qualitative analysis results of volatile compounds demonstrated that a total of 78 kinds of volatile compounds were detected in the pit mud, including 46, 45, 39 and 49 kinds in the pit mud from F-S, G-Z, H-X and I-D, respectively. Ester and acid were the two main components in the pit mud. Meanwhile, the correlation between microorganisms and main volatile compounds in the pit mud was analyzed. Moreover, Lentimicrobium, Syner-01 and Blvii28_wastewater-sludge group were found for the first time in the pit mud used for manufacturing Taorong-type Baijiu. The findings of this study could provide a theoretical foundation for improving the quality of pit mud and the flavor of Taorong-type Baijiu.


2020 ◽  
Vol 96 (2) ◽  
Author(s):  
Kärt Kanger ◽  
Nigel G H Guilford ◽  
HyunWoo Lee ◽  
Camilla L Nesbø ◽  
Jaak Truu ◽  
...  

ABSTRACT Solid organic waste is a significant source of antibiotic resistance genes (ARGs) and effective treatment strategies are urgently required to limit the spread of antimicrobial resistance. Here, we studied ARG diversity and abundance as well as the relationship between antibiotic resistome and microbial community structure within a lab-scale solid-state anaerobic digester treating a mixture of food waste, paper and cardboard. A total of 10 samples from digester feed and digestion products were collected for microbial community analysis including small subunit rRNA gene sequencing, total community metagenome sequencing and high-throughput quantitative PCR. We observed a significant shift in microbial community composition and a reduction in ARG diversity and abundance after 6 weeks of digestion. ARGs were identified in all samples with multidrug resistance being the most abundant ARG type. Thirty-two per cent of ARGs detected in digester feed were located on plasmids indicating potential for horizontal gene transfer. Using metagenomic assembly and binning, we detected potential bacterial hosts of ARGs in digester feed, which included Erwinia, Bifidobacteriaceae, Lactococcus lactis and Lactobacillus. Our results indicate that the process of sequential solid-state anaerobic digestion of food waste, paper and cardboard tested herein provides a significant reduction in the relative abundance of ARGs per 16S rRNA gene.


2014 ◽  
Vol 955-959 ◽  
pp. 3635-3639 ◽  
Author(s):  
Ji Hua Wang ◽  
Xue Gong ◽  
Jian Fei Guan ◽  
Hui Yan Xing

The reclaimed water treated in a Harbin recycled water plant has been taken as a target of research, by using microbial traditional culture method and tablet coated counting method, discussing the influence of the reclaimed water irrigation on soil microbial community structure through the method of short-term indoor simulated soil column irrigation. The results shows that the reclaimed water irrigation can significantly increase the quantity of bacteria and actinomycetes in the surface 0-20 cm layer soil, but it has little affect on 20-40 cm and 40-60 cm layer soil. Microbial community structure and diversity were changed relatively with the irrigation of reclaimed water, which embodied the increase or decrease of dominant and subdominant groups, the disappearance of non-dominant groups sensitive to reclaimed water, the appear or disappear of the other part of the occasional groups.


2020 ◽  
Author(s):  
Bernard N. Kanoi ◽  
Maribet Gamboa ◽  
Doris Ngonzi ◽  
Thomas G. Egwang

AbstractMicrobial community structure changes are key in detecting and characterizing the impacts of anthropogenic activities on aquatic ecosystems. Here, we evaluated the effect of river pollution of industrial and urban sites on the microbial community composition and distribution in the Nakivubo wetland and its catchment areas in Lake Victoria basin, Uganda. Samples were collected from two industrial and one urban polluted sites and the microbial diversity was analyzed based on a 16S rRNA gene clone library. Differences in microbial diversity and community structure were observed at different sampling points. Bacteria associated with bioremediation were found in sites receiving industrial waste, while a low proportion of important human-pathogenic bacteria were seen in urban polluted sites. While Escherichia spp. was the most dominant genus of bacteria for all sites, three unique bacteria, Bacillus sp., Pseudomonas sp., Thermomonas sp., which have been reported to transform contaminants such as heavy metals and hydrocarbons (such as oils) by their metabolic pathways were also identified. Our results may serve as a basis for further studies assessing microbial community structure changes among polluted sites at Nakivubo Water Channel for management and monitoring. The diversity of natural microbial consortia could also be a rich bioprospecting resource for novel industrial enzymes, medicinal and bioactive compounds.


Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 507 ◽  
Author(s):  
Santisak Kitjanukit ◽  
Kyohei Takamatsu ◽  
Naoko Okibe

Natural attenuation of Mn(II) was observed inside the metal refinery wastewater pipeline, accompanying dark brown-colored mineralization (mostly MnIVO2 with some MnIII2O3 and Fe2O3) on the inner pipe surface. The Mn-deposit hosted the bacterial community comprised of Hyphomicrobium sp. (22.1%), Magnetospirillum sp. (3.2%), Geobacter sp. (0.3%), Bacillus sp. (0.18%), Pseudomonas sp. (0.03%), and non-metal-metabolizing bacteria (74.2%). Culture enrichment of the Mn-deposit led to the isolation of a new heterotrophic Mn(II)-oxidizer Pseudomonas sp. SK3, with its closest relative Ps. resinovorans (with 98.4% 16S rRNA gene sequence identity), which was previously unknown as an Mn(II)-oxidizer. Oxidation of up to 100 mg/L Mn(II) was readily initiated and completed by isolate SK3, even in the presence of high contents of MgSO4 (a typical solute in metal refinery wastewaters). Additional Cu(II) facilitated Mn(II) oxidation by isolate SK3 (implying the involvement of multicopper oxidase enzyme), allowing a 2-fold greater Mn removal rate, compared to the well-studied Mn(II)-oxidizer Ps. putida MnB1. Poorly crystalline biogenic birnessite was formed by isolate SK3 via one-electron transfer oxidation, gradually raising the Mn AOS (average oxidation state) to 3.80 in 72 h. Together with its efficient in vitro Mn(II) oxidation behavior, a high Mn AOS level of 3.75 was observed with the pipeline Mn-deposit sample collected in situ. The overall results, including the microbial community structure analysis of the pipeline sample, suggest that the natural Mn(II) attenuation phenomenon was characterized by robust in situ activity of Mn(II) oxidizers (including strain SK3) for continuous generation of Mn(IV). This likely synergistically facilitated chemical Mn(II)/Mn(IV) synproportionation for effective Mn removal in the complex ecosystem established in this artificial pipeline structure. The potential utility of isolate SK3 is illustrated for further industrial application in metal refinery wastewater treatment processes.


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