Novosphingobium arvoryzae sp. nov., isolated from a flooded rice field

Genomic and physiological characterization of Novosphingobium terrae sp. nov., an alphaproteobacterium isolated from Cerrado soil containing a mega-sized chromid

A novel bacterial strain, designated GeG2T, was isolated from soils of the native Cerrado, a highly biodiverse savanna-like Brazilian biome. 16S rRNA gene analysis of GeG2T revealed high sequence identity (100%) to the alphaproteobacterium Novosphingobium rosa; however, comparisons with N. rosa DSM 7285T showed several distinctive features, prompting a full characterization of the new strain in terms of physiology, morphology, and, ultimately, its genome. GeG2T cells were Gram-stain-negative bacilli, facultatively anaerobic, motile, positive for catalase and oxidase activities, and starch hydrolysis. Strain GeG2T presented planktonic-sessile dimorphism and cell aggregates surrounded by extracellular matrix and nanometric spherical structures were observed, suggesting the production of exopolysaccharides (EPS) and outer membrane vesicles (OMVs). Despite high 16S rDNA identity, strain GeG2T showed 90.38% average nucleotide identity and 42.60% digital DNA-DNA hybridization identity with N. rosa, below species threshold. Whole-genome assembly revealed four circular replicons: a 4.1 Mb chromosome, a 2.7 Mb extrachromosomal megareplicon, and two plasmids (212.7 and 68.6 kb). The megareplicon contains a few core genes and plasmid-type replication/maintenance systems, consistent with its classification as a chromid. Genome annotation shows a vast repertoire of carbohydrate-active enzymes and genes involved in the degradation of aromatic compounds, highlighting the biotechnological potential of the new isolate. Chemotaxonomic features, including polar lipid and fatty acid profiles, as well as physiological, molecular, and whole-genome comparisons showed significant differences between strain GeG2T and N. rosa, indicating that it represents a novel species, for which the name Novosphingobium terrae is proposed. The type strain is GeG2T (= CBMAI 2313T = CBAS 753 T).

Metagenome analyses of microbial population in geotextile fabrics used in permeable reactor barriers for toluene biodegradation

Toluene is one of the hydrocarbons that contaminate soil and groundwater, and has a high cost to remediate, which makes it an environmental pollutant of concern. This study aimed to find bacterial distribution from nonwoven geotextile (GT) fabric specimens in a pilot-scale permeable reactive barrier (PRB). Upon 167 days of incubation with the addition of toluene, the microbial community on the GT surfaces (n = 12) was investigated by the 16S rRNA metagenome sequencing approach. According to taxonomic classification, the Proteobacteria phylum dominated the metagenomes of all the geotextile samples (80-90%). Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway database search of the toluene degradation mechanism revealed the susceptible toluene-degrading species. For the toluene-to-benzoate degradation, the Cupriavidus genus, particularly C. gilardii, C. metallidurans, and C. taiwanensis, are likely to be functional. In addition to these species, the Novosphingobium genus was abundantly localized in the GTs, in particular Novosphingobium sp. ABRDHK2. The results suggested the biodegradation potential of these species in toluene remediation. Overall, this work sheds light on the variety of microorganisms found in the geotextile fabrics used in PRBs and the species involved in the biodegradation of toluene from several sources, including soil, sediment, and groundwater.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03460-y.

Novosphingobium percolationis sp. nov. and Novosphingobium huizhouense sp. nov., isolated from landfill leachate of a domestic waste treatment plant

Two strains designated as c1T and c7T, were isolated from the landfill leachate of a domestic waste treatment plant in Huizhou City, Guangdong Province, PR China. The cells of both strains were aerobic, rod-shaped, non-motile and formed yellow colonies on Reasoner’s 2A agar plates. Strain c1T grew at 10–42 °C (optimum, 30 °C), pH 4.5–10.5 (optimum, pH 7.0) and 0–2.0 % (w/v) NaCl (optimum, 0–0.5 %). Strain c7T grew at 10–42 °C (optimum, 30 °C), pH 4.5–10.5 (optimum, pH 6.0) and 0–2.0 % (w/v) NaCl (optimum, 0–0.5 %). Phylogenetic analyses revealed that strains c1T and c7T belong to the genus Novosphingobium . The 16S rRNA gene sequence similarities of strains c1T and c7T to the type strains of Novosphingobium species were 94.5–98.2 % and 94.3–99.1 %, respectively. The calculated pairwise average nucleotide identity values among strains c1T, c7T and the reference strains were in the range of 75.2–85.9 % and the calculated pairwise average amino acid identity values among strains c1T, c7T and reference strains were in the range of 72.0–88.3 %. Their major respiratory quinone was Q-10, and the major cellular fatty acids were C18 : 1  ω7c, C18 : 0, C16 : 1  ω7c, C16 : 0 and C14 : 0 2OH. The major polar lipids of strains c1T and c7T were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, sphingoglycolipid, unidentified lipids and unidentified phospholipid. Based on phenotypic, chemotaxonomic, phylogenetic and genomic results from this study, strains c1T and c7T should represent two independent novel species of Novosphingobium , for which the names Novosphingobium percolationis sp. nov. (type strain c1T=GDMCC 1.2555T=KCTC 82826T) and Novosphingobium huizhouense sp. nov. (type strain c7T=GDMCC 1.2556T=KCTC 82827T) are proposed. The gene function annotation results of strains c1T and c7T suggest that they could play an important role in the degradation of organic pollutants.

Novosphingobium decolorationis sp. nov., an aniline blue-decolourizing bacterium isolated from East Pacific sediment

Aniline blue-decolourizing bacterial strain 502str22^T, isolated from sediment collected in the East Pacific, was subjected to characterization by a polyphasic taxonomic approach. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain 502str22^T belongs to the genus Novosphingobium, with closely related type strains 'Novosphingobium profundi' F72^T (97.6%), N. mathurense SM117^T (97.1%) and N. arvoryzae Jyi-02^T (97.0%). Digital DNA-DNA hybridization and average nucleotide identity values between strain 502str22^T and closely related type strains were 20.3-24.8% and 74.1-81.9%, respectively. The major cellular fatty acid (>10%) was C_18:1 ω7c. The polar lipid profile consisted of a mixture of phosphatidylcholine, one sphingoglycolipid, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylmonomethylethanolamine. The DNA G+C content of strain 502str22^T was 65.5 mol%. The polyphasic taxonomic results indicated that strain 502str22^T represents a novel species of the genus Novosphingobium, for which the name Novosphingobium decolorationis sp. nov is proposed. The type strain is 502str22^T (=KCTC 82134^T= MCCC 1K04799 ^T).

Comparative Genomics of Degradative Novosphingobium Strains With Special Reference to Microcystin-Degrading Novosphingobium sp. THN1

Bacteria in genus Novosphingobium associated with biodegradation of substrates are prevalent in environments such as lakes, soil, sea, wood and sediments. To better understand the characteristics linked to their wide distribution and metabolic versatility, we report the whole genome sequence of Novosphingobium sp. THN1, a microcystin-degrading strain previously isolated by Jiang et al. (2011) from cyanobacteria-blooming water samples from Lake Taihu, China. We performed a genomic comparison analysis of Novosphingobium sp. THN1 with 21 other degradative Novosphingobium strains downloaded from GenBank. Phylogenetic trees were constructed using 16S rRNA genes, core genes, protein-coding sequences, and average nucleotide identity of whole genomes. Orthologous protein analysis showed that the 22 genomes contained 674 core genes and each strain contained a high proportion of distributed genes that are shared by a subset of strains. Inspection of their genomic plasticity revealed a high number of insertion sequence elements and genomic islands that were distributed on both chromosomes and plasmids. We also compared the predicted functional profiles of the Novosphingobium protein-coding genes. The flexible genes and all protein-coding genes produced the same heatmap clusters. The COG annotations were used to generate a dendrogram correlated with the compounds degraded. Furthermore, the metabolic profiles predicted from KEGG pathways showed that the majority of genes involved in central carbon metabolism, nitrogen, phosphate, sulfate metabolism, energy metabolism and cell mobility (above 62.5%) are located on chromosomes. Whereas, a great many of genes involved in degradation pathways (21-50%) are located on plasmids. The abundance and distribution of aromatics-degradative mono- and dioxygenases varied among 22 Novosphingoibum strains. Comparative analysis of the microcystin-degrading mlr gene cluster provided evidence for horizontal acquisition of this cluster. The Novosphingobium sp. THN1 genome sequence contained all the functional genes crucial for microcystin degradation and the mlr gene cluster shared high sequence similarity (≥85%) with the sequences of other microcystin-degrading genera isolated from cyanobacteria-blooming water. Our results indicate that Novosphingobium species have high genomic and functional plasticity, rearranging their genomes according to environment variations and shaping their metabolic profiles by the substrates they are exposed to, to better adapt to their environments.