Impact of different doses of deltamethrine on soil microbial density and crop growth

The effects of agrochemicals pollution on soil nutrients, soil microbes as well as plants cultivated on the soil were studied. Insecticide and herbicide were used to impact on the soil samples across concentration gradients. Bean and maize seeds were planted in separate experiments to monitor the effects of the agrochemicals on the plants. The microbial diversity and the physicochemical characteristics of the soil before and after pollution were determined using standard methods. Chlorophyll contents of the leaves were also determined after planting. Results indicated that bacterial isolates such as Enterococcus sp 54(40%), Staphylococcus sp 8(13%), Bacillus sp 46(34%) and Micrococcus sp 15(11%) and fungal isolates such as Penicillium sp 41(34%), Saccharomyces sp 67(56%), Yeast sp 4(3%), Geotrichum sp 6 (5%) and Aspergillus sp 1(1.8%) were recovered from treated and untreated soil with the percentages representing after planting. From the results, the herbicide treated soils indicated that the Total Heterotrophic Bacterial Count (THBC) increased after cultivation while the Total Heterotrophic Fungal Count (THFC) decreased after cultivation. On the other hand, the insecticides treated soils recorded a general decrease in THFC and THBC after cultivation. The total nitrogen (TN) and available phosphorus (AP) had no significant differences before and after planting while the exchangeable potassium (EP) had significant increase recorded after planting. Plants generally had poor growth characteristics recorded by stem girth and length, as well as chlorophyll content.

Gastroesophageal reflux disease is associated with differences in the allograft microbiome, microbial density and inflammation in lung transplantation

RationaleGastroesophageal reflux disease (GERD) may affect lung allograft inflammation and function through its effects on allograft microbial community composition in lung transplant recipients.ObjectivesOur objective was to compare the allograft microbiota in lung transplant recipients with or without clinically diagnosed GERD in the first post-transplant year, and assess associations between GERD, allograft microbiota, inflammation and acute and chronic lung allograft dysfunction (ALAD/CLAD).Methods268 bronchoalveolar lavage samples were collected from 75 lung transplant recipients at a single transplant centre every 3 months post-transplant for 1 year. Ten transplant recipients from a separate transplant centre provided samples pre/post-anti-reflux Nissen fundoplication surgery. Microbial community composition and density were measured using 16S rRNA gene sequencing and qPCR, respectively and inflammatory markers and bile acids were quantified.Measurements and Main ResultsWe observed three community composition profiles (labelled community state types, CSTs 1-3). Transplant recipients with GERD were more likely to have CST1, characterized by high bacterial density and relative abundance of the oropharyngeal colonizing genera Prevotella and Veillonella. GERD was associated with more frequent transition to CST1. CST1 was associated with lower per-bacteria inflammatory cytokine levels than the pathogen-dominated CST3. Time-dependant models revealed associations between CST3 and development of ALAD/CLAD. Nissen fundoplication decreased bacterial load and pro-inflammatory cytokines.ConclusionGERD was associated with a high bacterial density, Prevotella/Veillonella dominated CST1. CST3, but not CST1 or GERD, was associated with inflammation and early development of ALAD/CLAD. Nissen fundoplication was associated with decreases in microbial density in BALF samples, especially the CST1-specific genus, Prevotella.

Mechanisms and Evolution of Heritable Microbial Density in Insect Hosts

Within-host density is a critically important aspect of vertically transmitted symbioses that influences the fitness of both hosts and microbes. I review recent studies of symbiont density in insects, including my laboratory’s work on pea aphids and maternally transmitted bacteria.

Two-Target Quantitative PCR To Predict Library Composition for Shallow Shotgun Sequencing

When determining human microbiota composition, shotgun sequencing is a powerful tool that can generate large amounts of data. However, in sample compositions with low or variable microbial density, shallowing sequencing can negatively affect resulting data.

Larval breeding sites of the mosquito Aedes aegypti in forest and domestic habitats in Africa and the potential association with oviposition evolution

Adaptations to anthropogenic domestic habitats contribute to the success of mosquito Aedes aegypti as a major global vector of several arboviral diseases. The species inhabited African forests before expanding into domestic habitats and spreading to the rest of the world. Despite a well-studied evolutionary history, how this species initially moved into human settlements in Africa remains unclear. During this initial habitat transition, Ae. aegypti switched from using natural containers like tree holes as larval breeding sites to using artificial containers like clay pots. Little is known about how these natural versus artificial containers differ in their environments, or whether Ae. aegypti in forest versus domestic habitats evolved any corresponding incipient behavioral divergence, such as in oviposition. To address these gaps, we first characterized physical characteristics, larval density, microbial density, bacterial composition, and volatile profiles of natural versus artificial containers used as mosquito larval breeding sites. We focused on two localities in Africa, La Lopé, Gabon and Rabai, Kenya. In both localities, our data showed that the two habitat-specific container types had significantly different characteristics. We then examined whether such containers differed in their attractiveness for oviposition, a key behavior affecting larval distribution. Forest Ae. aegypti readily accepted artificial containers in our field experiments, and laboratory choice experiments did not find distinct oviposition preference between forest and village Ae. aegypti colonies. These results suggested that African Ae. aegypti were likely generalists in their oviposition site choice. This flexibility to accept different containers might play a vital role during the initial domestication of Ae. aegypti, allowing the mosquitoes to use human-stored water as fallback breeding sites during dry seasons. Although ovipositional changes were not present initially, after longer domestic habitat breeding, the mosquitoes did evolve divergence oviposition preference, as suggested by previous comparisons of African Ae. aegypti and human-specialized non-African Ae. aegypti.

A comparative study of soil-water characteristic curves for compacted lateritic soil – bacillus coagulans mixtures

A comparative study of soil-water characteristic curves (SWCCs) for compacted lateritic soil ̶ Bacillus coagulans (B. coagulans) mixtures for municipal solid waste (MSW) application was studied. Soil treatment was performed at approximately about one-third pore volume of the microbes (i.e., B. coagulans) for suspension densities of 0, 1.5×108, 6.0×108, 1.2×109, 1.8×109 and 2.4×109cells/ml, correspondingly. Soil specimens were prepared at optimum moisture content (OMC) of British Standard light (BSL) compaction energy. Cementation reagent was applied on the compacted soil and permitted to penetrate until partial saturation was achieved. A set-up of pressure plate extractor was employed to measure the volumetric water content, θ (VWC) in the laboratory for varying matric suctions with a minimum of 10 kPa up to a maximum of 1,500 kPa. The unsaturated hydraulic conductivity (UHC) and VWC were assessed using Brooks - Corey (BC) and Fredlund - Xing (FX) models. Largely, BC and FX models overrated the VWC. Also, the VWC decreased with higher matric suction for the two models considered and the laboratory measured values. The UHC predicted for matric suctions of 500 and 1,500 kPa initially decreased for B. coagulans suspension density up to 1.2×109 cells/ml for BC and FX models, with the exception of a few cases, but thereafter increased with increase in microbial density. For FX model at 1,500 kPa, UHC values of 2.42×10–9, 2.02×10–9, 9.31×10–10, 8.09×10–10 , 1.29×10–9 and 2.27×10–9m/s were recorded at 0, 1.5×108, 6.0×108, 1.2×109, 1.8×109 and 2.4×109cells/ml, respectively. In the case of BC model, values of 2.26×10–17, 1.41×10–14, 2.2×10–14, 4.6×10–19 , 3.25×10–17 and 2.45×10–14m/s were recorded at 0, 1.5×108, 6.0×108, 1.2×109, 1.8×109 and 2.4×109cells/ml, respectively. Thus, the FX model met the design maximum hydraulic conductivity value of 1 x 10–9 m/s requirement for MSW system when lateritic soil was treated with B. coagulans suspension density of 1.2×109 cells/ml, while the BC model satisfied the requirement for all the microbial densities considered and it is recommended for modelling of UHC of lateritic soil admixed with B. coagulans for MSW containment application.