A Thermostable Bilirubin-Oxidizing Enzyme from Activated Sludge Isolated by a Metagenomic Approach

Metagenomic Approaches as a Tool to Unravel Promising Biocatalysts from Natural Resources: Soil and Water

Natural resources are considered a promising source of microorganisms responsible for producing biocatalysts with great relevance in several industrial areas. However, a significant fraction of the environmental microorganisms remains unknown or unexploited due to the limitations associated with their cultivation in the laboratory through classical techniques. Metagenomics has emerged as an innovative and strategic approach to explore these unculturable microorganisms through the analysis of DNA extracted from environmental samples. In this review, a detailed discussion is presented on the application of metagenomics to unravel the biotechnological potential of natural resources for the discovery of promising biocatalysts. An extensive bibliographic survey was carried out between 2010 and 2021, covering diverse metagenomic studies using soil and/or water samples from different types and locations. The review comprises, for the first time, an overview of the worldwide metagenomic studies performed in soil and water and provides a complete and global vision of the enzyme diversity associated with each specific environment.

Characterization of the circulating microbiome in acute-on-chronic liver failure associated with hepatitis B

BACKGROUND

Patients with hepatitis B-related acute-on-chronic liver failure (HB-ACLF) may have an increased circulating microbial burden. This study aimed to assess circulating microbial load and composition and to explore the association between the circulating microbiome and both systemic inflammation (SI) and clinical outcome in HB-ACLF.

METHODS

Plasma from 50 HB-ACLF patients, 23 healthy controls and 25 patients with compensated liver cirrhosis (C-LC) was analysed for chemokines/cytokines and bacterial DNA and further analysed by 16S rDNApyrosequencing. Linear discriminant analysis effect size (LEfSe) and inferred metagenomics analyses were performed.

RESULTS

The circulating bacterial DNA was significantly increased in HB-ACLF patients compared to that in the control groups. The overall microbial diversity was significantly decreased in HB-ACLF patients. HB-ACLF patients were enriched with Moraxellaceae, Sulfurovum, Comamonas and Burkholderiaceae but were depleted in Actinobacteria, Deinococcus-Thermus, Alphaproteobacteria, Xanthomonadaceae and Enterobacteriaceae compared to controls. Network analysis revealed a direct positive correlation between Burkholderiaceae and chemokine IP-10 in HB-ACLF patients. The relative abundance of Prevotellaceae independently predicted 28-day mortality. Inferred functional metagenomics predicted an enrichment of bacteria with genes related to methane, alanine, aspartate, glutamate, pyrimidine, purine and energy metabolism.

CONCLUSIONS

HB-ACLF patients display increased circulating microbial burden, altered microbiome composition and a shift in microbiome functionality. The alteration in circulating microbiota is associated with SI and clinical outcome in HB-ACLF.

Bacteria That Make a Meal of Sulfonamide Antibiotics: Blind Spots and Emerging Opportunities

The release of sulfonamide antibiotics into the environment is alarming because the existence of these antibiotics in the environment may promote resistance in clinically relevant microorganisms, which is a potential threat to the effectiveness of antibiotic therapies. Controllable biodegradation processes are of particular significance for the inexpensive yet effective restoration of sulfonamide-contaminated environments. Cultivation-based techniques have already made great strides in successfully isolating bacteria with promising sulfonamide degradation abilities, but the implementation of these isolates in bioremediation has been limited by unknown microbial diversity, vast population responsiveness, and the impact of perturbations from open and complex environments. Advances in DNA sequencing technologies and metagenomic analyses are being used to complement the information derived from cultivation-based procedures. In this Review, we provide an overview of the growing understanding of isolated sulfonamide degraders and identify shortcomings of the prevalent literature in this field. In addition, we propose a technical paradigm that integrates experimental testing with metagenomic analysis to pave the way for improved understanding and exploitation of these ecologically important isolates. Overall, this Review aims to outline how metagenomic studies of isolated sulfonamide degraders are being applied for the advancement of bioremediation strategies for sulfonamide contamination.