Genomic Analysis of the Yet-Uncultured Binatota Reveals Broad Methylotrophic, Alkane-Degradation, and Pigment Production Capacities

ABSTRACT The recent leveraging of genome-resolved metagenomics has generated an enormous number of genomes from novel uncultured microbial lineages yet left many clades undescribed. Here, we present a global analysis of genomes belonging to Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. All orders in Binatota encoded the capacity for aerobic methylotrophy using methanol, methylamine, sulfomethanes, and chloromethanes as the substrates. Methylotrophy in Binatota was characterized by order-specific substrate degradation preferences, as well as extensive metabolic versatility, i.e., the utilization of diverse sets of genes, pathways, and combinations to achieve a specific metabolic goal. The genomes also encoded multiple alkane hydroxylases and monooxygenases, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids (lycopene, β- and γ-carotenes, xanthins, chlorobactenes, and spheroidenes) production. Further, the majority of genes involved in bacteriochlorophyll a, c, and d biosynthesis were identified, although absence of key genes and failure to identify a photosynthetic reaction center preclude proposing phototrophic capacities. Analysis of 16S rRNA databases showed the preferences of Binatota to terrestrial and freshwater ecosystems, hydrocarbon-rich habitats, and sponges, supporting their potential role in mitigating methanol and methane emissions, breakdown of alkanes, and their association with sponges. Our results expand the lists of methylotrophic, aerobic alkane-degrading, and pigment-producing lineages. We also highlight the consistent encountering of incomplete biosynthetic pathways in microbial genomes, a phenomenon necessitating careful assessment when assigning putative functions based on a set-threshold of pathway completion. IMPORTANCE A wide range of microbial lineages remain uncultured, yet little is known regarding their metabolic capacities, physiological preferences, and ecological roles in various ecosystems. We conducted a thorough comparative genomic analysis of 108 genomes belonging to the Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. We present evidence that members of the order Binatota specialize in methylotrophy and identify an extensive repertoire of genes and pathways mediating the oxidation of multiple one-carbon (C1) compounds in Binatota genomes. The occurrence of multiple alkane hydroxylases and monooxygenases in these genomes was also identified, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids production. We also report on the presence of incomplete chlorophyll biosynthetic pathways in all genomes and propose several evolutionary-grounded scenarios that could explain such a pattern. Assessment of the ecological distribution patterns of the Binatota indicates preference of its members to terrestrial and freshwater ecosystems characterized by high methane and methanol emissions, as well as multiple hydrocarbon-rich habitats and marine sponges.

Potential for and Distribution of Enzymatic Biodegradation of Polystyrene by Environmental Microorganisms

Polystyrene (PS) is one of the main polymer types of plastic wastes and is known to be resistant to biodegradation, resulting in PS waste persistence in the environment. Although previous studies have reported that some microorganisms can degrade PS, enzymes and mechanisms of microorganism PS biodegradation are still unknown. In this study, we summarized microbial species that have been identified to degrade PS. By screening the available genome information of microorganisms that have been reported to degrade PS for enzymes with functional potential to depolymerize PS, we predicted target PS-degrading enzymes. We found that cytochrome P4500s, alkane hydroxylases and monooxygenases ranked as the top potential enzyme classes that can degrade PS since they can break C–C bonds. Ring-hydroxylating dioxygenases may be able to break the side-chain of PS and oxidize the aromatic ring compounds generated from the decomposition of PS. These target enzymes were distributed in Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes, suggesting a broad potential for PS biodegradation in various earth environments and microbiomes. Our results provide insight into the enzymatic degradation of PS and suggestions for realizing the biodegradation of this recalcitrant plastic.

Methylotrophy, alkane-degradation, and pigment production as defining features of the globally distributed yet-uncultured phylum Binatota

The recent leveraging of genome-resolved metagenomics has opened a treasure trove of genomes from novel uncultured microbial lineages, yet left many clades undescribed. We here present a global analysis of genomes belonging to the Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. All orders in the Binatota encoded the capacity for aerobic methylotrophy using methanol, methylamine, sulfomethanes, chloromethanes, and potentially methane as substrates. Methylotrophy in the Binatota was characterized by order-specific substrate degradation preferences, as well as extensive metabolic versatility, i.e. the utilization of diverse sets of genes, pathways and combinations to achieve a specific metabolic goal. The genomes also encoded an arsenal of alkane hydroxylases and monooxygenases, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids (lycopene, β and γ carotenes, xanthins, chlorobactenes, and spheroidenes) production. Further, the majority of genes involved in bacteriochlorophyll a, c, and d biosynthesis were identified; although absence of key genes and failure to identify a photosynthetic reaction center precludes proposing phototrophic capacities. Analysis of 16S rRNA databases showed Binatota’s preferences to terrestrial and freshwater ecosystems, hydrocarbon-rich habitats, and sponges supporting their suggested potential role in mitigating methanol and methane emissions, alkanes degradation, and nutritional symbiosis with sponges. Our results expand the lists of methylotrophic, aerobic alkane degrading, and pigment-producing lineages. We also highlight the consistent encountering of incomplete biosynthetic pathways and gene shrapnel in microbial genomes, a phenomenon necessitating careful assessment when assigning putative functions based on a set-threshold of pathway completion.

Methylotrophy, alkane-degradation, and pigment production as defining features of the globally distributed yet-uncultured phylum Binatota

The recent leveraging of genome-resolved metagenomics has opened a treasure trove of genomes from novel uncultured microbial lineages, yet left many clades undescribed. We here present a global analysis of genomes belonging to the Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. All orders in the Binatota encoded the capacity for aerobic methylotrophy using methanol, methylamine, sulfomethanes, chloromethanes, and potentially methane as substrates. Methylotrophy in the Binatota was characterized by order-specific substrate degradation preferences, as well as extensive metabolic versatility, i.e. the utilization of diverse sets of genes, pathways and combinations to achieve a specific metabolic goal. The genomes also encoded an arsenal of alkane hydroxylases and monooxygenases, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids (lycopene, β and γ carotenes, xanthins, chlorobactenes, and spheroidenes) production. Further, the majority of genes involved in bacteriochlorophyll a, c, and d biosynthesis were identified; although absence of key genes and failure to identify a photosynthetic reaction center precludes proposing phototrophic capacities. Analysis of 16S rRNA databases showed Binatota’s preferences to terrestrial and freshwater ecosystems, hydrocarbon-rich habitats, and sponges supporting their suggested potential role in mitigating methanol and methane emissions, alkanes degradation, and nutritional symbiosis with sponges. Our results expand the lists of methylotrophic, aerobic alkane degrading, and pigment-producing lineages. We also highlight the consistent encountering of incomplete biosynthetic pathways and gene shrapnel in microbial genomes, a phenomenon necessitating careful assessment when assigning putative functions based on a set-threshold of pathway completion.

Characteristics of hydrocarbon hydroxylase genes in a thermophilic aerobic biological system treating oily produced wastewater

Alkane and aromatic hydroxylase genes in a full-scale aerobic system treating oily produced wastewater under thermophilic condition (45–50 °C) in the Jidong oilfield, China, were investigated using clone library and quantitative polymerase chain reaction methods. Rather than the normally encountered integral-membrane non-haem iron monooxygenase (alkB) genes, only CYP153-type P450 hydroxylase genes were detected for the alkane activation, indicating that the terminal oxidation of alkanes might be mainly mediated by the CYP153-type alkane hydroxylases in the thermophilic aerobic process. Most of the obtained CYP153 gene clones showed distant homology with the reference sequences, which might represent novel alkane hydroxylases. For the aromatic activation, the polycyclic aromatic hydrocarbon-ring hydroxylating dioxygenase (PAH-RHD) gene was derived from Gram-negative PAH-degraders belonging to the Burkholderiales order, with a 0.72% relative abundance of PAH-RHD gene to 16S rRNA gene. This was consistent with the result of 16S rRNA gene analysis, indicating that Burkholderiales bacteria might play a key role in the full-scale process of thermophilic hydrocarbon degradation.

Structural and mechanistic insight into alkane hydroxylation by Pseudomonas putida AlkB

Integral membrane non-haem di-iron alkane hydroxylases (AlkBs) are enzymes of unknown structure that allow bacteria to grow on alkanes. Catalysis-linked modifications with the inhibitor 1-octyne, mutagenesis studies and ab initio modelling provided novel insights into the structure and function of AlkB.