Herbicides applied to combat weeds and increase crop yields may also have undesired effects on beneficial soil microorganisms. Field studies were conducted in 2005 and 2006 in Zaria, Nigeria, to evaluate the response of weeds and soil microorganisms to imazaquin applied at 0.05, 0.10, 0.20 and 0.40 kg a.i./ha and pendimethalin applied at 1.0, 2.0, 4.0, and 8.0 kg a.i./ha in cowpea and soybean. Hoeweeded and unweeded (no herbicide) plots were controls. Both herbicides significantly reduced weed biomass in both crops, when compared to the unweeded control, which had the highest weed biomass at all sampling dates. Treatments with 0.40 kg a.i./ha of imazaquin, 2.0 and 4.0 kg a.i./ha of pendimethalin, and the hoe-weeded control, had the highest cowpea grain yield. The unweeded control had the lowest grain yield which was comparable to that in all other herbicide treatments. All treatments except 4.0 and 8.0 kg a.i./ha of pendimethalin had higher soybean grain yield than the unweeded control. Soybean yield was lowest in the unweeded control, and treatments that received 4.0 and 8.0 kg a.i./ha of pendimethalin. All rates of imazaquin gave similar soybean grain yields that were 29e41% higher than that from pendimethalin. The hoe-weeded control had the highest yield, which was 79% more than that in the unweeded control. Higher rates of imazaquin and pendimethalin reduced nodulation, nitrogen fixation, and vesicular arbuscular mycorrhizal (VAM) fungi colonisation in both crops. VAM fungi species diversity and species richness in cowpea rhizosphere soil and species diversity in soybean rhizosphere soil were reduced relative to the controls due to application of both herbicides with the rates of 0.10, 0.20, and 0.40 kg a.i./ha of imazaquin and 8.0 kg a.i./ha of pendimethalin being significantly effective.

Agro-food, petroleum, textile, and leather industries generate saline wastewater with a high content of organic pollutants such as aromatic hydrocarbons, phenols, nitroaromatics, and azo dyes. Halophilic microorganisms are of increasing interest in industrial waste treatment, due to their ability to degrade hazardous substances efficiently under high salt conditions. However, their full potential remains unexplored. The isolation and identification of halophilic and halotolerant microorganisms from geographically unrelated and geologically diverse hypersaline sites supports their application in bioremediation processes. Past investigations in this field have mainly focused on the elimination of polycyclic aromatic hydrocarbons and phenols, whereas few studies have investigated N-aromatic compounds, such as nitro-substituted compounds, amines, and azo dyes, in saline wastewater. Information regarding the growth conditions and degradation mechanisms of halophilic microorganisms is also limited. In this review, we discuss recent research on the removal of organic pollutants such as organic matter, in terms of chemical oxygen demand (COD), dyes, hydrocarbons, N-aliphatic and N-aromatic compounds, and phenols, in conditions of high salinity. In addition, some proposal pathways for the degradation of aromatic compounds are presented.

Organic potatoes are in demand, although their cultivation is difficult due to lower yields and disease problems. A field study carried out in Sri Lanka illustrated that using good quality organic manures combined with the technology of Effective Microorganisms (EM) in a system of Nature Farming could enhance yields of organic potatoes and also reduce disease incidence significantly. The prospects of producing organic potatoes are presented on the basis of this study.

Based on 454 pyrosequencing of 16S rRNA gene amplicons, microbial communities in samples collected from seven wells, six of which had positive paraffin deposition reduction and one with negative paraffin deposition reduction upon a microbial treatment designed for the prevention of paraffin precipitation, were analyzed. Microbial communities’ structures were significantly different for the samples from the negative well and the positive wells. Microbes affiliated with Diaphorobacter belonging to β-Proteobacteria were predominant in the negative well, While γ-Proteobacteria-affiliated microbes of Pseudomonas and Enterobacter and Firmicute-affiliated Bacillus were shared and dominant in the positive wells. Microbes shared in the positive wells could be considered as potential candidates for investigations into microbial paraffin control. In addition, microbial activity of hydrocarbon-degradation and microbial products such as biosurfactants were proposed to be the main potential mechanisms for the microbial treatment for the prevention of paraffin precipitation.

Milk is naturally a good provider of a whole range of nutrients, however an inadequate milking may significantly interfere on its nutritional and microbiological quality. The main purpose of this study was to isolate and identify microorganisms from bulk tanks of southern Rio Grande do Sul state, Brazil and establish a correlation between animal management and presence of pathogens in the milk. To this end, raw milk samples were collected from different dairy herds and submitted to microbiological analyses. Mean bacterial counts were Staphylococcus sp. (5,32x106 CFU/mL), S. aureus (1,33x105 CFU/mL) and enterobacteria (1,82x107 CFU/mL). The major pathogens isolated and their respective frequency were Escherichia coli (27.8%), Streptococcus agalactiae (6.2%), S. dysgalactiae (37.2%), S. uberis (16.8%), Candida sp. (15.7%), Aspergillus sp. (5.8%), Trichosporum sp. (3.6%) and Cryptococcus sp. (1.5%). In addition, it was identified an Odds Ratio of 3.2 for S. agalactiae regarding manual milking and 3.1 when a single cloth towel was used for drying the udder. For S. bovis the Odds Ratio was 2.8 in properties milking their animals in stalls wood. Somatic cell count (SCC) was significantly higher (p=0,003) in milk samples manually extracted in comparison with machine milking. Likewise, manual milking resulted in the increase in S. aureus counts (p=0.04). Pre-dipping practice have contributed for a significant reduction (p=0.04) in the Staphylococcus sp. counts. Taken together, our results show that the adoption of poor management practices can negatively interfere in the microbiological quality of milk increasing the risks of occurrence of pathogens and their counts.

Particulate matter (PM) air pollution poses a formidable public health threat to the city of Beijing. Among the various hazards of PM pollutants, microorganisms in PM₂.₅ and PM₁₀ are thought to be responsible for various allergies and for the spread of respiratory diseases. While the physical and chemical properties of PM pollutants have been extensively studied, much less is known about the inhalable microorganisms. Most existing data on airborne microbial communities using 16S or 18S rRNA gene sequencing to categorize bacteria or fungi into the family or genus levels do not provide information on their allergenic and pathogenic potentials. Here we employed metagenomic methods to analyze the microbial composition of Beijing’s PM pollutants during a severe January smog event. We show that with sufficient sequencing depth, airborne microbes including bacteria, archaea, fungi, and dsDNA viruses can be identified at the species level. Our results suggested that the majority of the inhalable microorganisms were soil-associated and nonpathogenic to human. Nevertheless, the sequences of several respiratory microbial allergens and pathogens were identified and their relative abundance appeared to have increased with increased concentrations of PM pollution. Our findings may serve as an important reference for environmental scientists, health workers, and city planners.

Secondary succession studies have mainly focused on plants, but little is known about the fate of soil microbial communities and their relationship with plant succession after disturbance, particularly in dry ecosystems. We examined changes in soil properties and of plant and soil microbial communities across a chronosequence of abandoned arable fields that included five successional stages according to time of abandonment stretching near a century. We hypothesized the existence of a parallel secondary succession above- and below-ground and explored the possible linkages between plant and microbial communities as well as the role of changes in soil properties over the successional gradient. Soil microbial communities were characterized by PLFAs analysis, enzymatic activities, and pyrosequencing of the 16S rDNA. We found clear patterns of plant and microbial secondary succession characterized by an increase in organic C, NH4+, and silt content as well as in soil microbial biomass and activity along the successional stages, linked to an increase in plant productivity and diversity. Plant and microbial composition were significantly different among successional stages, although no distinct microbial communities were observed in the two initial stages, suggesting that microbial succession may lag behind plant succession. However, the degree of change in the composition of soil microbial communities and plant communities across our chronosequence evidenced that above- and below-ground secondary succession developed with similar patterns and correlated with changes in multiple ecosystem functions such as increases in above-and below-ground productivity, diversity and nutrient accumulation as plant and microbial succession progressed.

Both ammonia-oxidizing bacteria (AOB) and archaea (AOA) might be the key microorganisms in ammonia conversion in ecosystems. However, the depth-related change of AOA and AOB in sediment ecosystem is still not clear. The relative contribution of AOA and AOB to nitrification in wetland sediment remains also unclear. Moreover, information about ammonia-oxidizing microorganisms in high-altitude freshwater wetland is still lacking. The present study investigated the relative abundances and community structures of AOA and AOB in sediments of a high-altitude freshwater wetland in Yunnan Province (China). Variations of the relative abundances and community structures of AOA and AOB were found in the wetland sediments, dependent on both sampling site and sediment depth. The relative abundances of AOA and AOB (0.04–3.84 and 0.01–0.52 %) and the AOA/AOB ratio (0.12–4.65) showed different depth-related change patterns. AOB community size was usually larger than AOA community size. AOB diversity was usually higher than AOA diversity. AOA diversity decreased with the increase of sediment depth, while AOB diversity showed no obvious link with the sediment depth. Pearson’s correlation analysis showed that AOA diversity had a positive significant correlation with available phosphorus. Nitrosospira-like sequences, with different compositions, predominated in the wetland sediment AOB communities. This work could provide some new insights toward nitrification in freshwater sediment ecosystems.

Large amounts of airborne microorganisms are emitted from livestock production. These emitted microorganisms may associate with dust, and are suspected to pose a risk of airborne infection to humans in vicinity and to animals on other farms. However, the extent to which airborne transmission may play a role in the epidemic, and how dust acts as a carrier of microorganisms in the transmission processes is unknown. The authors present the current knowledge of the entire process of airborne transmission of microorganisms—from suspension and transportation until deposition and infection—and their relation to dust. The sampling and the mitigation techniques of airborne microorganisms and dust in livestock production systems are introduced as well.