Random changes in the heifer rumen in bacterial community structure, physico-chemical and fermentation parameters, and in vitro fiber degradation

The study characterized the changes in physico-chemical properties and bacterial community structure during mesophilic anaerobic digestion (AD) of pit latrine sludge. The sludge was sampled from six different pits six times at an interval of 40 days. Standard techniques were used to assess the changes in pollution indicators including COD and faecal coliforms. Metagenomic DNA from a composite sample from the six pits’ sludge was then extracted at Days 0, 14 and 35 and directly sequenced followed by analysis of the microbial structure using the Ribosomal Database Project tools. Multivariate analyses were used to identify the main determinants of microbial community structure during the digestion process. AD significantly reduced the levels of pollution indicators (p < 0.05). Total solids, volatile solids and COD were reduced by 17–27%, 52–79%, and 42– 63%, respectively. The indicator pathogenic microorganisms FC and E. coli were reduced by 34–54% and 35–60%, respectively. The reduction in terms of COD and BOD were, however, not sufficient to satisfy the standards for safe disposal into the environment. Proteobacteria were the most dominant bacterial phylum in the undigested sludge (24.1%) and were significantly reduced to 2.5% at the peak of the AD (Day 14) up until Day 35. Firmicutes significantly increased (p < 0.05) from 22.4% to 28.8% at Day 14 before being reduced to 11.6% at Day 35. This study contributes to our understanding of AD of pit latrine faecal sludge through mesophilic AD as a baseline study, and helps to inform future research on mesophilic AD.

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Steam Explosion Pretreatment Changes Ruminal Fermentation in vitro of Corn Stover by Shifting Archaeal and Bacterial Community Structure

Frontiers in Microbiology ◽

10.3389/fmicb.2020.02027 ◽

2020 ◽

Vol 11 ◽

Author(s):

Kun Wang ◽

Xuemei Nan ◽

Jinjin Tong ◽

Guangyong Zhao ◽

Linshu Jiang ◽

...

Keyword(s):

Community Structure ◽

Bacterial Community ◽

Corn Stover ◽

Bacterial Community Structure ◽

Steam Explosion ◽

Ruminal Fermentation ◽

Steam Explosion Pretreatment

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Influence of hydrological factors on bacterial community structure in a tropical monsoonal estuary in India

10.21203/rs.3.rs-281357/v1 ◽

2021 ◽

Author(s):

Parvathi Ammini ◽

Michela R Catena ◽

Jasna Vijayan ◽

Nikhil Phadke ◽

Nikhita Gogate

Keyword(s):

Community Structure ◽

Bacterial Community ◽

Bacterial Communities ◽

Bacterial Community Structure ◽

Salinity Gradient ◽

Pearson Correlation ◽

Temporal Variations ◽

Spatial And Temporal Variation ◽

Physico Chemical ◽

The Impact

Abstract In the present study, we analysed variations in bacterial community structure along a salinity gradient in a tropical monsoonal estuary (Cochin estuary, CE), on the southwest coast of India, using Illumina next-generation sequencing (NGS). Water samples were collected from eight different locations thrice a year, to assess the variability in the bacterial community structure and to determine the physico-chemical factors influencing the bacterial diversity. Proteobacteria was the most dominant phyla in the estuary followed by Bacteroidetes, Cyanobacteria, Actinobacteria, and Firmicutes. Statistical analysis indicated significant variations in bacterial communities between freshwater, mesohaline and euryhaline regions, as well as between the monsoon (wet) and non-monsoon (dry) periods. Non-metric multidimensional scaling (NMDS) analysis demonstrated that the bacterial communities cluster according to different salinity regimes of the estuary. Canonical Correspondence analysis (CCA) showed a clear spatial and temporal variation in the distribution of bacterial communities in the CE. Abundance of Betaproteobacteria was high in the freshwater regions, while Gammaproteobacteria, Alphaproteobacteria and Epsilonproteobactera were more abundant in mesohaline and euryhaline regions of the estuary. Correlagram based on Pearson correlation analysis demonstrated the impact of different physico-chemical variables on the distribution of dominant phyla, class and genera. Spatial and temporal variations in bacterial community structure could be due to regional variations in environmental conditions imparted by allochthonous inputs, monsoonal rainfall, and tidal influence.

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Unraveling the Molecular Mechanisms Underlying the Nasopharyngeal Bacterial Community Structure

mBio ◽

10.1128/mbio.00009-16 ◽

2016 ◽

Vol 7 (1) ◽

Cited By ~ 6

Author(s):

Wouter A. A. de Steenhuijsen Piters ◽

Debby Bogaert

Keyword(s):

Community Structure ◽

Bacterial Community ◽

Bacterial Community Structure ◽

Molecular Mechanisms ◽

Commensal Bacteria ◽

Upper Respiratory Tract ◽

Interspecies Interactions ◽

Severe Infections

ABSTRACT The upper respiratory tract is colonized by a diverse array of commensal bacteria that harbor potential pathogens, such as Streptococcus pneumoniae . As long as the local microbial ecosystem—also called “microbiome”—is in balance, these potentially pathogenic bacterial residents cause no harm to the host. However, similar to macrobiological ecosystems, when the bacterial community structure gets perturbed, potential pathogens can overtake the niche and cause mild to severe infections. Recent studies using next-generation sequencing show that S. pneumoniae , as well as other potential pathogens, might be kept at bay by certain commensal bacteria, including Corynebacterium and Dolosigranulum spp. Bomar and colleagues are the first to explore a specific biological mechanism contributing to the antagonistic interaction between Corynebacterium accolens and S. pneumoniae in vitro [L. Bomar, S. D. Brugger, B. H. Yost, S. S. Davies, K. P. Lemon, mBio 7(1):e01725-15, 2016, doi:10.1128/mBio.01725-15]. The authors comprehensively show that C. accolens is capable of hydrolyzing host triacylglycerols into free fatty acids, which display antipneumococcal properties, suggesting that these bacteria might contribute to the containment of pneumococcus. This work exemplifies how molecular epidemiological findings can lay the foundation for mechanistic studies to elucidate the host-microbe and microbial interspecies interactions underlying the bacterial community structure. Next, translation of these results to an in vivo setting seems necessary to unveil the magnitude and importance of the observed effect in its natural, polymicrobial setting.

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