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Diverse and complex microbiomes are found in virtually every environment on Earth. Bacteria and fungi often co-dominate environmental microbiomes, and there is growing recognition that bacterial-fungal interactions (BFI) have significant impacts on the functioning of their associated microbiomes, environments, and hosts. Investigating BFI in vitro remains a challenge, particularly when attempting to examine interactions at multiple scales of system complexity. Fabricated devices can provide control over both biotic composition and abiotic factors within an experiment to enable the characterization of diverse BFI phenotypes such as modulation of growth rate, production of biomolecules, and alterations to physical movements. Engineered devices ranging from microfluidic chips to simulated rhizosphere systems have been and will continue to be invaluable to BFI research, and it is anticipated that such devices will continue to be developed for diverse applications in the field. This will allow researchers to address specific questions regarding the nature of BFI and how they impact larger microbiome and environmental processes such as biogeochemical cycles, plant productivity, and overall ecosystem resilience. Devices that are currently used for experimental investigations of bacteria, fungi, and BFI are discussed herein along with some of the associated challenges and several recommendations for future device design and applications. [ABSTRACT FROM AUTHOR]

In this study, we investigated the temporal and spatial quantitative changes in the concentration of antibiotic resistance gene (ARG) markers in a municipal wastewater treatment plant (WWTP). Four ARGs conferring resistance to different classes of antibiotics (ermB, sul1, tet[W], and blaCTXM) and a gene used as a proxy for ARG pollution (intl1) were quantified in two separate sampling campaigns covering two and half years of operation of the WWTP. First, a systematic monthly monitoring of multiple points in the inlet and the outlet revealed an absolute decrease in the concentration of all analyzed ARGs. However, the relative abundance of sul1 and intl1 genes relative to the total bacterial load (estimated using the universal marker 16S rDNA) increased in the outlet samples as compared to the inlet. To pinpoint the exact stage of removal and/or enrichment within the WWTP, a second sampling including the stages of the biological treatment was performed bimonthly. This revealed a distinct enrichment of sul1 and intl1 genes during the biological treatment phase. Moreover, the temporal and spatial variations in ARG abundance patterns within the WWTP underscored the complexity of the dynamics associated with the removal of ARGs during wastewater treatment. Understanding these dynamics is pivotal for developing efficient strategies to mitigate the dissemination of ARGs in aquatic environments. Practitioner points: Regular monitoring of ARG markers in WWTPs is essential to assess temporal and spatial changes, aiding in the development of effective mitigation strategies.Understanding the dynamics of ARG abundance during biological treatment is crucial for optimizing processes and minimizing dissemination in aquatic environments.Increased relative abundance of certain ARGs highlights potential enrichment during wastewater treatment, necessitating targeted interventions.Systematic monitoring of multiple points within WWTPs can provide valuable insights into the efficacy of treatment processes in reducing ARG levels over time.The complexity of ARG abundance patterns underscores the need to develop holistic approaches to tackle antibiotic resistance in wastewater systems. [ABSTRACT FROM AUTHOR]

Dissolved organic matter and microorganisms were analyzed along the flow path of a geothermal facility in Austria. Various analytical methods were used to characterize and differentiate between natural and synthetic organic matter, characterize the microbial community composition, and determine the implications of microorganisms in an operating a geothermal site. Dissolved organic carbon (DOC) concentrations were in the range of 8.4-10.3 mg CL-1 and typically decreased from the production to the injection side. Carbonate scalings are avoided in the facility by the injection of a chemical scaling inhibitor within the production well at 500 m depth. It was calculated that the inhibitor contributes approximately 1 mg CL-1 DOC to the produced fluids. Ion chromatography (IC), liquid chromatography -- organic carbon detection (LC-OCD) and Fouriertransform ion cyclotron resonance mass spectrometry (FT-ICR-MS) in negative electrospray ionization (ESI(-)) and positive atmospheric pressure photoionization (APPI(+)) mode were applied to the fluid samples to characterize the dissolved organic matter (DOM) composition and distinguish between the inhibitor and the natural DOM. Depending on the applied ionization mode, FT-ICR-MS results show that between 31 % and 65 % of the macromolecular formulas detected in the fluid samples seem to originate from the inhibitor. However, the DOM is mainly composed of low molecular weight acids (LMWA), especially acetate with up to 7.4 mg CL-1. The microbial community composition varied along the flowpath with dominant phyla being Firmicutes, Proteobacteria, and Thermotogae. Based on the microorganisms found in the sample, the metabolic pathways have been assessed. Acetate might be produced by microorganisms through various fermentation processes (e.g. from lysine, pyruvate and hexitol). Assessing the presence and interaction of organic compounds and microorganisms in geothermal fluids provides a broader understanding of processes within the geothermal facility. This understanding could be beneficial for the efficient use of a geothermal power plant. [ABSTRACT FROM AUTHOR]

Endosporulation is a complex morphophysiological process resulting in a more resistant cellular structure that is produced within the mother cell and is called endospore. Endosporulation evolved in the common ancestor of Firmicutes, but it is lost in descendant lineages classified as asporogenic. While Kurthia spp. is considered to comprise only asporogenic species, we show here that strain 11kri321, which was isolated from an oligotrophic geothermal reservoir, produces phase‐bright spore‐like structures. Phylogenomics of strain 11kri321 and other Kurthia strains reveals little similarity to genetic determinants of sporulation known from endosporulating Bacilli. However, morphological hallmarks of endosporulation were observed in two of the four Kurthia strains tested, resulting in spore‐like structures (cryptospores). In contrast to classic endospores, these cryptospores did not protect against heat or UV damage and successive sub‐culturing led to the loss of the cryptosporulating phenotype. Our findings imply that a cryptosporulation phenotype may have been prevalent and subsequently lost by laboratory culturing in other Firmicutes currently considered as asporogenic. Cryptosporulation might thus represent an ancestral but unstable and adaptive developmental state in Firmicutes that is under selection under harsh environmental conditions. [ABSTRACT FROM AUTHOR]

Oxalate oxidation and carbonate precipitation associated with the oxalogenic treeTerminalia belliricawere investigated. Calcium oxalate crystals, oxalotrophic bacteria (dominated by generaMethylobacteriumandBurkholderia), and carbonate accumulation (82% dry weight), were detected in the bark. In contrast, only a slight accumulation of carbonate was observed in soil (1.5%). The combined geochemical and microbiological analyses suggest that bark of an Indian living tree represents a novel habitat for the accumulation of carbonate associated with bacterial oxalate oxidation. The importance of these types of habitats needs to be quantified when considering the biogeochemical cycling of carbon and calcium in tropical ecosystems. [ABSTRACT FROM AUTHOR]