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A Gram-stain-negative bacterium, designated strain LB-8T, was isolated from an activated sludge sample collected from a factory in Binzhou city, Shandong province, PR China. Cells of strain LB-8T were strictly aerobic, non-motile and rod-shaped. Growth occurred at 15–40 °C (optimum, 30 °C), at pH 6.0–9.0 (optimum, pH 7.0) and at 0–7.5 % (w/v) NaCl (optimum, 0.5 % NaCl). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain LB-8T formed a distinct phyletic branch within the family Chitinophagaceae and was most closely related to members of the genera Flavisolibacter , Cnuella and Paracnuella with 92.7–93.3 % 16S rRNA gene sequence similarities. The average amino acid identity values between strain LB-8T and its closed phylogenetic neighbours Flavisolibacter , Cnuella and Paracnuella were below 70 % supporting that strain LB-8T was a member of a novel genus. The predominant cellular fatty acids of LB-8T were iso-C15 : 0, anteiso-C15 : 0, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and iso-C17 : 0 3-OH, and the only isoprenoid quinone was menaquinone-7 (MK-7). The major polar lipids of strain LB-8T were phosphatidylethanolamine, four unidentified aminolipids and two unidentified lipids. The genome size of strain LB-8T was 7.01 Mbp with 41.2 mol% G+C content. On the basis of the evidence presented in this study, strain LB-8T represents a novel species of a new genus in the family Chitinophagaceae , for which the name Paraflavisolibacter caeni gen. nov., sp. nov. (type strain LB-8T=GDMCC 1.3631T=KCTC 92688T) is proposed.

Synergistic regulation of the expression of various genes in a catabolic pathway is crucial for the degradation, survival, and adaptation of microorganisms in polluted environments. However, how a single regulator accurately regulates and controls differential transcriptions of various catabolic genes to ensure metabolic safety remains largely unknown. Here, a LysR-type transcriptional regulator (LTTR), OdcR, encoded by the regulator gene odcR, was confirmed to be essential for 3,5-dibromo-4-hydroxybenozate (DBHB) catabolism and simultaneously activated the transcriptions of a gene with unknown function, orf419, and three genes, odcA, odcB, and odcC, involved in the DBHB catabolism in Pigmentiphaga sp. strain H8. OdcB further metabolized the highly toxic intermediate 2,6-dibromohydroquinone, which was produced from DBHB by OdcA. The upregulated transcriptional level of odcB was 7- to 9-fold higher than that of orf419, odcA, or odcC in response to DBHB. Through an electrophoretic mobility shift assay and DNase I footprinting assay, DBHB was found to be the effector and essential for OdcR binding to all four promoters of orf419, odcA, odcB, and odcC. A single nucleotide mutation in the regulatory binding site (RBS) of the promoter of odcB (TAT-N(11)-ATG), compared to those of odcA/orf419 (CAT-N(11)-ATG) and odcC (CAT-N(11)-ATT), was identified and shown to enable the significantly higher transcription of odcB. The precise regulation of these genes by OdcR via a single nucleotide mutation in the promoter avoided the accumulation of 2,6-dibromohydroquinone, ensuring the metabolic safety of DBHB. IMPORTANCE Prokaryotes use various mechanisms, including improvement of the activity of detoxification enzymes, to cope with toxic intermediates produced during catabolism. However, studies on how bacteria accurately regulate differential transcriptions of various catabolic genes via a single regulator to ensure metabolic safety are scarce. This study revealed a LysR-type transcriptional activator, OdcR, which strongly activated odcB transcription for the detoxification of the toxic intermediate 2,6-dibromohydroquinone and slightly activated the transcriptions of other genes (orf419, odcA, and odcC) for 3,5-dibromo-4-hydroxybenozate (DBHB) catabolism in Pigmentiphaga sp. strain H8. Interestingly, the differential transcription/expression of the four genes, which ensured the metabolic safety of DBHB in cells, was determined by a single nucleotide mutation in the regulatory binding sites of the four promoters. This study describes a new and ingenious regulatory mode of ensuring metabolic safety in bacteria, expanding our understanding of synergistic transcriptional regulation in prokaryotes.

Triclocarban, one of the emerging pollutants, has been accumulating, and it is frequently detected in wastewater. Due to its toxicity and persistence, the efficient removal of triclocarban from wastewater systems is challenging. Genetic bioaugmentation with transferable catabolic plasmids has been considered to be a long-lasting method to clean up pollutants in continuous flow wastewater treatment systems. In this study, bioaugmentation with Pseudomonas putida KT2440, harboring the transferrable triclocarban-catabolic plasmid pDCA-1-gfp-tccA2, rapidly converted 50 μM triclocarban in wastewater into 3,4-dichloroaniline and 4-chloroaniline, which are further mineralized more easily. RT-qPCR results showed that the ratio of the copy number of pDCA-1-gfp-tccA2 to the cell number of strain KT2440 gradually increased during genetic bioaugmentation, suggesting horizontal transfer and proliferation of the plasmid. By using DNA stable isotope probing (SIP) and amplicon sequencing, OTU86 (Escherichia-Shigella), OTU155 (Citrobacter), OTU5 (Brucella), and OTU15 (Enterobacteriaceae) were found to be the potential recipients of the plasmid pDCA-1-gfp-tccA2 in the wastewater bacterial community. Furthermore, three transconjugants in the genera of Escherichia, Citrobacter, and Brucella showing triclocarban-degrading abilities were isolated from the wastewater. This study develops a new method for removing triclocarban from wastewater and provides insights into the environmental behavior of transferrable catabolic plasmids in bacterial community in wastewater systems.

A strictly aerobic, Gram-stain-negative, rod-shaped, yellow, non-spore-forming bacterial strain, designated P-25T, was isolated from soil collected in Yantai, Shandong Province, PR China. The temperature, pH and NaCl concentration ranges for the growth of strain P-25T were 10–37 °C (optimum, 28–30 °C), pH 6.0–9.0 (optimum, pH 7.5–8.0) and 0–4 % (w/v) (optimum, 1 % w/v), respectively. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain P-25T was most closely related to Pedobacter xixiisoli S27T (98.1 % 16S rRNA gene sequence similarity), followed by Pedobacter chitinilyticus CM134L-2T (97.2 %) and Pedobacter ureilyticus THG-T11T (97.1 %). The genomic DNA G+C content of strain P-25T based on its draft genome sequence was 38.1 %. MK-7 was the major respiratory quinone, and iso-C15 : 0, C16 : 1ω7c and/or C16 : 1ω6c (summed feature 3) and iso-C17 : 0 3-OH were the major fatty acids. The major polar lipids were phosphatidylethanolamine, one unidentified aminophospholipid, one unidentified phospholipid, two unidentified lipids, five unidentified aminolipids and two unidentified glycolipids. Average nucleotide identity values for the draft genomes between strain P-25T and strains S27T, CM134L-2T and THG-T11T were 81.8, 77.6 and 81.2 %, respectively, and the digital DNA–DNA hybridization (dDDH) values were 30.0, 19.2 and 27.6 %, respectively. Based on their phylogenetic and phenotypic characteristics, chemotaxonomic data, and dDDH results, strain P-25T is considered to represent a novel species of the genus Pedobacter , for which the name Pedobacter helvus sp. nov. is proposed; the type strain is strain P-25T (KCTC 62821T=CCTCC AB 2018185T).

A plethora of organic pollutants such as pesticides, polycyclic and halogenated aromatic hydrocarbons, and emerging pollutants, such as flame retardants, is continuously being released into the environment. This poses a huge threat to the society in terms of environmental pollution, agricultural product quality, and general safety. Therefore, effective removal of organic pollutants from the environment has become an important challenge to be addressed. As a consequence of the recent and rapid developments in additive manufacturing, 3D bioprinting technology is playing an important role in the pharmaceutical industry. At the same time, an increasing number of microorganisms suitable for the production of biomaterials with complex structures and functions using 3D bioprinting technology, have been identified. This article briefly discusses the principles, advantages, and disadvantages of different 3D bioprinting technologies for pollutant removal. Furthermore, the feasibility and challenges of developing bioremediation technologies based on 3D bioprinting have also been discussed.