Actinobacterial Communities of Chosen Extreme Habitats in China

Distribution of microbial communities in seasonally frozen soil layers on the Tibetan Plateau and the driving environmental factors

Large stocks of carbon and nitrogen stored in permafrost regions can potentially feed back to global biogeochemical cycles under climate warming. To understand the response of microbial communities to environmental changes, this study investigated the spatial distribution of bacterial communities in the upper layers (0-10, 10-20, and 20-30 cm) of seasonally frozen soil on the Tibetan Plateau and their relationships with the environmental factors. A total of 135 soil samples were collected from the soils at depths of 0-10, 10-20, and 20-30 cm in the Lhasa River and Nyang River basins, and the diversity and composition of bacterial communities in them were identified by high-throughput 16S rRNA gene sequencing. Bacterial diversity changed significantly with soil depth in the Nyang River basin (p < 0.001), while no obvious change was found in the Lhasa River basin. The whole bacterial composition exhibited small variations across different soil layers (p > 0.05). The relative abundance of aerobic bacteria, Sphingomonas and Arthrobacter, decreased with soil depth, while that of the other aerobic, facultative anaerobic, and anaerobic bacteria did not exhibit this trend. Soil pH was the key driving edaphic factor of the whole bacterial composition in all three depth layers, while vegetation also had an important influence on bacterial composition. Arthrobacter, Bradyrhizobium, and Bacillus had obvious correlations with soil nutrients or vegetation, while the other species were not significantly correlated with any environmental factors. Structural equation modeling revealed that vegetation and mean annual temperature had a key direct impact on the bacterial diversity and composition, respectively. Climate also indirectly affected bacterial communities, mainly through shaping soil pH and vegetation. These results indicate that the soil depth has a different impact on the bacterial α-diversity, whole bacterial composition, and specific taxa in the 0-30-cm surface layers of seasonally frozen soil, which were mainly determined by various environmental factors.

Rhodococcus strains as a good biotool for neutralizing pharmaceutical pollutants and obtaining therapeutically valuable products: Through the past into the future

Active pharmaceutical ingredients present a substantial risk when they reach the environment and drinking water sources. As a new type of dangerous pollutants with high chemical resistance and pronounced biological effects, they accumulate everywhere, often in significant concentrations (μg/L) in ecological environments, food chains, organs of farm animals and humans, and cause an intense response from the aquatic and soil microbiota. Rhodococcus spp. (Actinomycetia class), which occupy a dominant position in polluted ecosystems, stand out among other microorganisms with the greatest variety of degradable pollutants and participate in natural attenuation, are considered as active agents with high transforming and degrading impacts on pharmaceutical compounds. Many representatives of rhodococci are promising as unique sources of specific transforming enzymes, quorum quenching tools, natural products and novel antimicrobials, biosurfactants and nanostructures. The review presents the latest knowledge and current trends regarding the use of Rhodococcus spp. in the processes of pharmaceutical pollutants’ biodegradation, as well as in the fields of biocatalysis and biotechnology for the production of targeted pharmaceutical products. The current literature sources presented in the review can be helpful in future research programs aimed at promoting Rhodococcus spp. as potential biodegraders and biotransformers to control pharmaceutical pollution in the environment.