Syntrophic Interactions Within a Butane-Oxidizing Bacterial Consortium Isolated from Puguang Gas Field in China

Design and application of a novel culturing chip (cChip) for culturing the uncultured aquatic microorganisms

Culturing uncultured microorganisms is an important aspect of microbiology. Once cultured, these microorganisms can be a source of useful antibiotics, enzymes etc. In this study, we have designed a novel culturing chip (cChip) to facilitate the growth of uncultured aquatic bacterial community by concentrating the samples. cChip was optimized for microbial growth using known bacteria in the laboratory as a pre-experiment. Then microorganisms from a freshwater lake were concentrated and inoculated, before putting the inoculated cChip in a simulated lake environment and further sub-culturing on laboratory media. High-throughput sequencing and traditional culturing were also performed for comparison. These three methods were able to detect 265 genera of microorganisms in the sample, of which 78.87% were detected by high-throughput sequencing, 30.94% by cChip, while only 6.42% were obtained by traditional culture. Moreover, all microorganisms obtained by traditional culture were also cultured using the cChip. A total of 45 new strains were isolated from the cChip, and their 16S rRNA gene sequences were 91.35% to 98.7% similar to their closest relatives according to NCBI GenBank database. We conclude that the design and simple operation of cChip can improve the culture efficiency of traditional culture by almost 5 times. To the best of our knowledge, this is the first report comparing a novel culturing method with high-throughput sequencing data and traditional culturing of the same samples.

Islands Within Islands: Bacterial Phylogenetic Structure and Consortia in Hawaiian Lava Caves and Fumaroles

Lava caves, tubes, and fumaroles in Hawai‘i present a range of volcanic, oligotrophic environments from different lava flows and host unexpectedly high levels of bacterial diversity. These features provide an opportunity to study the ecological drivers that structure bacterial community diversity and assemblies in volcanic ecosystems and compare the older, more stable environments of lava tubes, to the more variable and extreme conditions of younger, geothermally active caves and fumaroles. Using 16S rRNA amplicon-based sequencing methods, we investigated the phylogenetic distinctness and diversity and identified microbial interactions and consortia through co-occurrence networks in 70 samples from lava tubes, geothermal lava caves, and fumaroles on the island of Hawai‘i. Our data illustrate that lava caves and geothermal sites harbor unique microbial communities, with very little overlap between caves or sites. We also found that older lava tubes (500–800 yrs old) hosted greater phylogenetic diversity (Faith's PD) than sites that were either geothermally active or younger (<400 yrs old). Geothermally active sites had a greater number of interactions and complexity than lava tubes. Average phylogenetic distinctness, a measure of the phylogenetic relatedness of a community, was higher than would be expected if communities were structured at random. This suggests that bacterial communities of Hawaiian volcanic environments are phylogenetically over-dispersed and that competitive exclusion is the main driver in structuring these communities. This was supported by network analyses that found that taxa (Class level) co-occurred with more distantly related organisms than close relatives, particularly in geothermal sites. Network “hubs” (taxa of potentially higher ecological importance) were not the most abundant taxa in either geothermal sites or lava tubes and were identified as unknown families or genera of the phyla, Chloroflexi and Acidobacteria. These results highlight the need for further study on the ecological role of microbes in caves through targeted culturing methods, metagenomics, and long-read sequence technologies.

Microbial Consortia Are Needed to Degrade Soil Pollutants

Soil pollution is one of the most serious environmental problems globally due to the weak self-purification ability, long degradation time, and high cost of cleaning soil pollution. The pollutants in the soil can be transported into the human body through water or dust, causing adverse effects on human health. The latest research has shown that the clean-up of soil pollutants through microbial consortium is a very promising method. This review provides an in-depth discussion on the efficient removal, bio-adsorption, or carbonated precipitation of organic and inorganic pollutants by the microbial consortium, including PAHs, BPS, BPF, crude oil, pyrene, DBP, DOP, TPHP, PHs, butane, DON, TC, Mn, and Cd. In view of the good degradation ability of the consortium compared to single strains, six different synergistic mechanisms and corresponding microorganisms are summarized. The microbial consortium obtains such activities through enhancing synergistic degradation, reducing the accumulation of intermediate products, generating the crude enzyme, and self-regulating, etc. Furthermore, the degradation efficiency of pollutants can be greatly improved by adding chemical materials such as the surfactants Tween 20, Tween 80, and SDS. This review provides insightful information regarding the application of microbial consortia for soil pollutant removal.

Selective pressure of biphenyl/polychlorinated biphenyls on the formation of aerobic bacterial associations and their biodegradative potential

Unique bacterial associations were formed in the polluted soils from territory of the industrial factories Open Joint Stock Company "The Middle Volga Chemical Plant," Chapaevsk, Russia and Open Joint Stock Company "Lubricant Producing Plant," Perm, Russia. This study evaluates the influence of the biphenyl/polychlorinated biphenyls (PCB) on the formation of aerobic bacterial associations and their biodegradative potential. Enrichment cultivation of the soil samples from the territories of these industrial factories with PCB (commercial mixture Sovol) was lead for forming aerobic bacterial enrichment cultures showing a unique composition. The dominating in these bacterial cultures was the phylum Proteobacteria (Beta- and Gammaproteobacteria). Using biphenyl as a carbon source led to decrease of biodiversity in the final stable bacterial associations. Periodic cultivation experiments demonstrated that the association PN2-B has a high degradative potential among the six studied bacterial associations. PN2-B degraded 100% mono-chlorobiphenyls (94.5 mg/L), 86.2% di-chlorobiphenyls (22.3 mg/L), 50.9% Sovol, and 38.4% Delor 103 (13.8 mg/L). Qualitative analysis of metabolites showed that association performed transformation of chlorobenzoic acids (PCB degradation intermediates) into metabolites of citrate cycle. Twelve individual strain-destructors were isolated. The strains were found to degrade 17.7-100% PCB1, 36.2-100% PCB2, 18.8-100% PCB3 (94.5 mg/L), and 15.7-78.2% PCB8 (22.3 mg/L). The strains were shown to metabolize chlorobenzoic acids formed during degradation of chlorobiphenyls. A unique ability of strains Micrococcus sp. PNS1 and Stenotrophomonas sp. PNS6 to degrade ortho-, meta-, and para-monosubstituted chlorobenzoic acids was revealed. Our results suggest that PN2-B and individual bacterial strains will be perspective for cleaning of the environment from polychlorinated biphenyls.

Microbiomes of China's Space Station During Assembly, Integration, and Test Operations

Sufficient evidence indicates that orbiting space stations contain diverse microbial populations, which may threaten astronaut health and equipment reliability. Understanding the composition of microbial communities in space stations will facilitate further development of targeted biological safety prevention and maintenance practices. Therefore, this study systematically investigated the microbial community of China's Space Station (CSS). Air and surface samples from 46 sites on the CSS and Assembly Integration and Test (AIT) center were collected, from which 40 bacteria strains were isolated and identified. Most isolates were cold- and desiccation-resistant and adapted to oligotrophic conditions. Bacillus was the dominant bacterial genus detected by both cultivation-based and Illumina MiSeq amplicon sequencing methods. Microbial contamination on the CSS was correlated with encapsulation staff activities. Analysis by spread plate and qPCR revealed that the CSS surface contained 2.24 × 10³-5.47 × 10³ CFU/100 cm² culturable bacteria and 9.32 × 10⁵-5.64 × 10⁶ 16S rRNA gene copies/100cm²; BacLight™ analysis revealed that the viable/total bacterial cell ratio was 1.98-13.28%. This is the first study to provide important systematic insights into the microbiome of the CSS during assembly that describes the pre-launch microbial diversity of the space station. Our findings revealed the following. (1) Bacillus strains and staff activities should be considered major concerns for future biological safety. (2) Autotrophic and multi-resistant microbial communities were widespread in the AIT environment. Although harsh cleaning methods reduced the number of microorganisms, stress-resistant strains were not completely removed. (3) Sampling, storage and analytical methods for the space station were thoroughly optimized, and are expected to be applicable to low-biomass environments in general. Microbiology-related future works will follow up to comprehensively understand the changing characteristics of microbial communities in CSS.

Novel Butane-Oxidizing Bacteria and Diversity of bmoX Genes in Puguang Gas Field

To investigate the diversity of butane-oxidizing bacteria in soils contaminated by long-term light hydrocarbon microseepage and the influence of butane on the soil microbial community, a quantitative study and identification of butane-oxidizing bacteria (BOB) in soils at the Puguang gas field were performed by DNA-based stable isotope probing (DNA-SIP). For the first time, two phylotypes corresponding to the genera Giesbergeria and Ramlibacter were identified as being directly involved in butane oxidation, in addition to the well-known light hydrocarbon degrader Pseudomonas. Furthermore, bmoX genes were strongly labeled by ¹³C-butane, and their abundances in gas field soils increased by 43.14-, 17.39-, 21.74-, and 30.14-fold when incubated with butane for 6, 9, 12, and 14 days, respectively, indicating that these bmoX-harboring bacteria could use butane as the sole carbon and energy source and they play an important role in butane degradation. We also found that the addition of butane rapidly shaped the bacterial community and reduced the diversity of bmoX genes in the gas field soils. These findings improve our understanding of BOB in the gas field environment and reveal the potential for their applications in petroleum exploration and bioremediation.