Influence of Gestational Hormones on the Bacteria-Induced Cytokine Response in Periodontitis

Periodontitis is an inflammatory disease that affects the supporting structures of teeth. The presence of a bacterial biofilm initiates a destructive inflammatory process orchestrated by various inflammatory mediators, most notably proinflammatory cytokines, which are upregulated in the gingival crevicular fluid, leading to the formation of periodontal pockets. This represents a well-characterized microbial change during the transition from periodontal health to periodontitis; interestingly, the gestational condition increases the risk and severity of periodontal disease. Although the influence of periodontitis on pregnancy has been extensively reviewed, the relationship between pregnancy and the development/evolution of periodontitis has been little studied compared to the effect of periodontitis on adverse pregnancy outcomes. This review is aimed at summarizing the findings on the pregnancy-proinflammatory cytokine relationship and discussing its possible involvement in the development of periodontitis. We address (1) an overview of periodontal disease, (2) the immune response and possible involvement of proinflammatory cytokines in the development of periodontitis, (3) how bone tissue remodelling takes place with an emphasis on the involvement of the inflammatory response and metalloproteinases during periodontitis, and (4) the influence of hormonal profile during pregnancy on the development of periodontitis. Finally, we believe this review may be helpful for designing immunotherapies based on the stage of pregnancy to control the severity and pathology of periodontal disease.

The Microbiome of the Reef Macroalga Sargassum ilicifolium in Singapore

The large canopy-forming macroalga, Sargassum ilicifolium, provides shelter and food for numerous coral reef species, but it can also be detrimental at high abundances where it outcompetes other benthic organisms for light and space. Here, we investigate the microbial communities associated with S. ilicifolium in Singapore, where it is an abundant and important member of coral reef communities. We collected eight complete S. ilicifolium thalli from eight island locations along an approximate 14 km east-to-west transect. Each thallus was dissected into three separate parts: holdfast, vesicles, and leaves. We then characterized the bacterial communities associated with each part via polymerase chain reaction (PCR) amplification of the 16S rRNA gene V4 region. We then inferred predicted metagenome functions using METAGENassist. Despite the comparatively short distances between sample sites, we show significant differences in microbial community composition, with communities further differentiated by part sampled. Holdfast, vesicles and leaves all harbor distinct microbial communities. Functional predictions reveal some separation between holdfast and leaf communities, with higher representation of sulphur cycling taxa in the holdfast and higher representation of nitrogen cycling taxa in the leaves. This study provides valuable baseline data that can be used to monitor microbial change, and helps lay the foundation upon which we can begin to understand the complexities of reef-associated microbial communities and the roles they play in the functioning and diversity of marine ecosystems.

Temperature and moisture content influences aggregate stability: linking climate induced microbial change to aggregate (de)stabilisation

<p>Soil is a critical resource that delivers numerous ecosystem services, yet this capacity is diminished by soil erosion and further threatened by the impacts of climate change. Soil erodibility is largely overlooked when considering soils’ response to climate change. Aggregate stability is widely recognised as a key indicator of soil erodibility and is influenced by multiple physical, chemical and biological mechanisms operating simultaneously. The microbial community has been reported to respond to changing climatic conditions, yet it remains unclear how microbial change influences microbially mediated aggregation and therefore aggregate stability. The microbial community in terms of composition, activity, and growth, can change over rapid timescales in response to climate conditions. The short timescale of such microbial shifts could rapidly impact microbially-mediated soil (de)stabilisation and aggregate stability.</p><p>The aim of this work is to experimentally test whether climatic conditions, in terms of temperature and moisture content, influence the microbial community and microbially-mediated soil (de)stabilisation, in turn influencing aggregate stability and soil erodibility. A series of laboratory-controlled experiments using environmental chambers and rainfall simulation examined the effects of temperature and moisture content in both static and fluctuating treatments on two surface soils (a sandy loam and a clay loam). Treatments were conducted with single layer aggregate microcosms and multi-layered soil trays to explore aggregate-scale mechanisms and the potential upscaling to run-off processes.        </p><p>Key findings from this research demonstrate that temperature and moisture content affect aggregate stability and the importance of climate induced microbial shifts influence on microbially mediated soil (de)stabilisation. Static temperature and moisture content conditions significantly affected aggregate stability, however the effects varied dependent on soil texture. Increasing temperature significantly increased aggregate stability in clay loam aggregates, while moisture content significantly decreased aggregate stability in sandy loam aggregates. Multiple regression analysis showed that aggregate stability was best predicted by soil moisture content, microbial biomass carbon, gram-negative bacterial abundance and fungal abundance in the sandy loam. Temperature was the sole significant predictor in the clay loam. Aggregate stability was significantly lower under fluctuating conditions and higher under static conditions. Aggregate stability was not significantly different between fluctuating climate treatments representing summer and winter cycles under future emission scenarios. Although, these treatments did significantly affect the microbial community. Our results have implications for our current understanding of microbial function in terms of soil stabilisation, and the relationship between climate, aggregate stability and soil erodibility.</p>

A 150-year record of phytoplankton community succession controlled by hydroclimatic variability in a tropical lake

Climate and human-induced environmental change promote biological regime shifts between alternate stable states, with implications for ecosystem resilience, function, and services. While these effects have been shown for present-day ecosystems, the long-term response of microbial communities has not been investigated in detail. This study assessed the decadal variations in phytoplankton communities in a ca. 150 year long sedimentary archive of Lake Nong Thale Prong (NTP), southern Thailand using a combination of bulk geochemical analysis, quantitative polymerase chain reaction (qPCR) and lipid biomarkers techniques including compound-specific hydrogen isotope analysis as a proxy for precipitation. Relatively drier and by inference warmer conditions from ca. 1857 to 1916 Common Era (CE) coincided with a dominance of the green algae Botryococcus braunii, indicating lower nutrient levels in the oxic lake surface waters, possibly related to lake water stratification. A change to higher silica (Si) input around 1916 CE was linked to increased rainfall and concurs with an abrupt takeover by diatom blooms lasting for 50 years. These were increasingly outcompeted by cyanobacteria from the 1970s onwards, most likely because of increased levels of anthropogenic phosphate and a reduction in rainfall. Our results showcase that the multi-proxy approach applied here provides an efficient way to track centennial-scale limnological, geochemical and microbial change, as influenced by hydroclimatic and anthropogenic forcing.

Study on Activated Sludge and Microbial Change in Membrane Bioreactor

With the characteristics of long SRT and high sludge concentration in MBR, the dynamic change of microbial community and the settleability of activated sludge have been the primary researches. According to observation of microbial from activated sludge consecutively, the change of the microbial population had a certain regularity: the free-swimming ciliates, the attached ciliates and the rotifera carried on the dominant populations in turn. With proliferation of the filamentous in activated sludge, the activated sludge floc became closely from loosely, resulted the microbial species and quantity in reduce. The total of activated sludge also rose along with the extent of SRT. The study found that there is a relationship of mutual influences and interactions between activated sludge and microorganism.