The copper resistance mechanism in a newly isolated Pseudoxanthomonas spadix ZSY-33.

Resolving the heavy metal resistance mechanisms of microbes is crucial for understanding the bioremediation of the ecological environment. In this study, a multiple heavy metal resistance bacterium, Pseudoxanthomonas spadix ZSY-33 was isolated and characterized. The copper resistance mechanism was revealed by analysis of the physiological traits, copper distribution, and genomic and transcriptomic data of strain ZSY-33 cultured with different concentrations of copper. The growth inhibition assay in basic medium showed that the growth of strain ZSY-33 was inhibited in the presence of 0.5 mM copper. The production of extracellular polymeric substances increased at a lower concentration of copper and decreased at a higher concentration of copper. Integrative analysis of genomic and transcriptomic, the copper resistance mechanism in strain ZSY-33 was elucidated. At a lower concentration of copper, the Cus and Cop systems were responsible for the homeostasis of intracellular copper. As the concentration of copper increased, multiple metabolism pathways, including the metabolism of sulfur, amino acids, and pro-energy were cooperated with the Cus and Cop systems to deal with copper stress. These results indicated a flexible copper resistance mechanism in strain ZSY-33, which may acquire from the long-term interaction with the living environment.

Runella salmonicolor sp. nov. and Dyella lutea sp. nov., isolated from paddy field soil.

Bacterial strains were collected from the soil of a paddy field around Dongguk University in Goyang, Republic of Korea. Two Gram-stain-negative, rod-shaped, aerobic or facultatively anaerobic bacterial strains were designated S5T and SaT. The results of analysis of phylogenetic trees based on 16S rRNA and whole-genome sequences indicated that these two strains represented a member of the genus Runella and a member of the genus Dyella, respectively. S5T exhibited 99.22, 98.10 and 97.68 % similarity to Runella rosea HYN0085T, Runella aurantiaca YX9T and Runella slithyformis DSM 19594T, respectively. S5T grew at 15-40 °C (optimum, 25 °C), at pH 6.5-12.0 (optimum, pH 9.5) and in the presence of 0-0.5 % (w/v) NaCl (optimum, 0 %). SaT exhibited 99.18 %, 98.36 %, 97.82 % and 97.68 % similarity to Dyella thiooxydans ATSB10T, Frateruia defendens DHoT, Fulvimonas yonginensis 5HGs31-2T and Dyella ginsengisoli Gsoil 3046T, respectively, and grew at 20-40 °C (optimum, 30 °C), at pH 5.5-11.0 (optimum, pH 8) and in the presence of 0-4.5 % (w/v) NaCl (optimum, 2.5 %). The average nucleotide identity difference values of S5T, SaT and the species reference strains were 92.16-93.62 % and 92.71-93.43%, which confirms that the S5T and SaT represent two novel species of the genera Runella and Dyella, respectively. The draft genome of S5T consisted of 7 048 502 bp, with a DNA G+C content of 44.9 % and that of SaT of 4 398 720 bp with a DNA G+C content of 67.9 %. The phylogenetic, phenotypic and physiological characteristics permitted the distinction of the two strains from their families, and we thus propose the names Runella salmonicolor sp. nov. (type strain S5T = KACC 22689T = TBRC 16343T) and Dyella lutea sp. nov. (type strain SaT=KACC 22690T = TBRC 16344T).

Dyella humicola sp. nov., Dyella subtropica sp. nov., Dyella silvatica sp. nov. and Dyella silvae sp. nov., isolated from subtropical forest soil.

Four novel bacterial strains, designated RBB1W86T, RXD159T, RBB189T and RLT163T, were isolated from subtropical forest soil of the Nanling National Nature Reserve located in Guangdong Province, PR China. 16S rRNA gene phylogeny indicated their affiliation to the genus Dyella, among which strains RBB1W86T and RXD159T were closely related to Dyella halodurans CGMCC 1.15435T with 16S rRNA gene sequence similarities of 98.8 and 99.5 %, respectively, and strains RBB189T and RLT163T were closely related to Dyella tabacisoli CGMCC 1.16273T (98.8 %) and Dyella japonica JCM 21530T (99.4 %), respectively. Phylogenomic analysis based on 92 core genes showed consistent phylogeny with the 16S rRNA gene phylogeny for strains RBB1W86T, RBB189T and RLT163T, while strain RXD159T showed a closer relationship with D. tabacisoli CGMCC 1.16273T and strain RBB189T. The genome-derived average nucleotide identity (ANI) values between the newly isolated strains and their closely related species were 70.18‒90.20 %, and the corresponding digital DNA-DNA hybridization (dDDH) values were 20.80‒40.30 %. Meanwhile, the ANI and dDDH values between each pair of the newly isolated strains were 75.80‒79.77 % and 21.30‒23.30 %, respectively. They all took iso-C15 : 0 and summed feature 9 (10-methyl C16  : 0 and/or iso-C17  : 1 ω9c) as the major fatty acids. Moreover, C16 : 0, iso-C16 : 0, iso-C17 : 0 and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) were also variously distributed as major components. They all took ubiquinone 8 as the only predominant respiratory quinone and phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid as the major polar lipids. Phosphatidylmethylethanolamine was only present in strain RBB189T as another major component. Based on the results of phenotypic, genotypic and chemotaxonomic analyses, the newly isolated strains could be clearly distinguished from their closely related species and should represent four distinct novel species of the genus Dyella, for which the names Dyella humicola sp. nov. (type strain RBB1W86T=GDMCC 1.1901T=KACC 21988T), Dyella subtropica sp. nov. (type strain RXD159T=GDMCC 1.1902T=KACC 21989T), Dyella silvatica sp. nov. (type strain RBB189T=GDMCC 1.1900T=KACC 21990 T) and Dyella silvae sp. nov. (type strain RLT163T=GDMCC 1.1916T=KACC 21991T) are proposed.

Rotations improve the diversity of rhizosphere soil bacterial communities, enzyme activities and tomato yield.

The use of rotations is an effective strategy to control crop diseases and improve plant health. The soil bacterial communities in the rhizosphere are highly important for maintaining soil productivity. However, the composition and structure of soil bacterial communities in the rotations of vegetable crops remain unclear. In this study, we explored the bacterial diversity and community structure of the tomato rhizosphere, including enzyme activities, yield, and fruit quality, under three different cropping systems: tomato-tomato (Solanum lycopersicum) continuous cropping (TY1), eggplant (Solanum melongena)-tomato rotation (TY2) and arrowhead (Sagittaria trifolia)-tomato rotation (TY3). The composition and diversity of the rhizosphere bacterial communities differed significantly. The diversity was more in the TY2 and TY3 treatments than those in the TY1 treatment. Chujaibacter and Rhodanobacter were two predominant and unique strains detected only in TY1, while the relative abundances of Curvibacter and Luteimonas were the highest in TY2 and TY3, respectively. Moreover, Lysobacter was a relatively abundant type of biocontrol bacterium found only in the TY3 treatment, which could contribute to alleviating the obstacle of tomato continuous cropping. Compared with the TY1 treatment, the activities of catalase were significantly higher in the TY2 and TY3 treatments. In addition, compared with TY1, the TY2 and TY3 plots increased the following parameters: tomato yields by 24-46%, total soluble solids by 37-93%, total organic acid by 10-15.7% and soluble protein by 10-21%, while the content of nitrate was significantly reduced by 23%. Altogether, compared with the tomato monoculture, the rotations of tomato with eggplant and arrowhead shifted the rhizosphere bacterial communities and improved the yield and quality of the tomato. Moreover, a tomato rotation, particularly with arrowhead, was an effective way to alleviate the obstacles of continuous cropping.

Phylogenomics and comparative genomic analyses support the creation of the novel family Ignatzschineriaceae fam. nov. comprising the genera Ignatzschineria and Wohlfahrtiimonas within the order Cardiobacteriales.

The genera Ignatzschineria and Wohlfahrtiimonas were originally classified as members of the family Xanthomonadaceae, order Xanthomonadales of the class Gammaproteobacteria. With the recent taxonomic revisions in the order Xanthomonadales, the two genera were left unclassified in both family and order level. As members of these genera were considered emerging pathogens, their proper classification is therefore relevant. Here, a phylogenomics and comparative genomic approach was used to ascertain the taxonomic position of the two genera. Result showed that the members of the two genera formed a highly supported monophyletic clade with the members of the order Cardiobacteriales. This close affiliation was further supported by the results of the comparative analysis of the 16S rRNA sequence similarity values. The comparative analyses of the 16S rRNA sequence similarity and average amino acid identity values also implied that the two genera represent a single novel family. Conserved signature indels (CSIs) in seven protein sequences were exclusively shared by the members of the novel family. In addition, four CSIs were also found to be useful in delimiting members of the two genera at the genus level. To accommodate the two genera in a single family within the order Cardiobacteriales, the name Ignatzschineriaceae fam. nov. is proposed.

Lysobacter sedimenti sp. nov., Isolated from the Sediment, and Reclassification of Luteimonas lumbrici as Lysobacter lumbrici comb. nov.

A bacterium, designated 50T was isolated from the sediment of a pesticide plant in Shandong Province, PR China. The strain was non-motile, Gram stain-negative, rod shaped and grew optimally on NA medium at 30 °C, pH 7.5 and with 0% (w/v) NaCl. Strain 50T showed the highest 16S rRNA gene sequence similarity with Lysobacter pocheonensis Gsoil 193T (96.7%), followed by Luteimonas lumbrici 1.1416T (96.5%). Phylogenetic analyses based on 16S rRNA indicated that strain 50T and Luteimonas lumbrici 1.1416T were clustered with the genus of Lysobacter and formed a subclade with Lysobacter pocheonensis Gsoil 193T. In the phylogenetic analysis based on the genome sequences, strain 50T and Luteimonas lumbrici 1.1416T were also clustered with the type strains of the genus Lysobacter. The obtained ANI and the dDDH value between 50T and Luteimonas lumbrici 1.1416T were 80.6% and 24.0%, respectively. The respiratory quinone was ubiquinone-8 (Q-8), and the major cellular fatty acids were iso-C15: 0 (31.7%), summed feature 9 (iso-C17:1 ω9c or C16:0 10-methyl) (23.7%), iso-C17:0 (14.3%) and iso-C16:0 (12.6%). The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and unidentified aminophospholipid, unidentified phospholipid and unidentified lipid. The genomic DNA G + C content was 69.5 mol%. According to the phenotypic, chemotaxonomic and phylogenetic analyses, strain 50T represents a novel species of the genus Lysobacter, for which the name Lysobacter sedimenti sp. nov. is proposed, with strain 50T (= KCTC 92088T = CCTCC AB 2022035T) as the type strain. In this study, it is also proposed that Luteimonas lumbrici should be transferred to the genus Lysobacter as Lysobacter lumbrici comb. nov. The type strain of Lysobacter lumbrici is 1.1416T (= KCTC 62979T = CCTCC AB 2018348T).

Dyella sedimenti sp. nov., Isolated from the Sediment of a Winery.

A Gram-staining negative, aerobic, non-motile and rod-shaped bacterium, designated strain N-S-14T, was isolated from the sediment of a winery in Guiyang, south-western China and subjected to a polyphasic taxonomic characteristics. The cells showed oxidase-negative and catalase-negative reactions. Growth occurred at 5-45 °C (optimum 30 °C), pH 5.0-8.0 (optimum pH 6.0-7.0) and with 0-3% (w/v) NaCl on R2A medium. The major respiratory quinone was ubiquinone-8 (Q-8). The predominant cellular fatty acids (> 10.0%) were identified as iso-C15:0, iso-C17:0 and summed feature 9 (iso-C17:1ω9c or C16:0 10-methyl). The profile of polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminophospholipid, one unidentified aminolipid and one unidentified lipid. The genomic DNA G + C content was 67.5%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain N-S-14T should be affiliated to the genus Dyella and formed a clade with most closely related Dyella solisilvae DHG54T (98.3%) and Dyella halodurans DHOG02T (97.8%). The digital DNA-DNA hybridization values ranged from 17.7 to 27.1% and the ANI values ranged from 75.2 to 84.0% between strain N-S-14T and other members of the genus Dyella, respectively, and thus the results indicated that strain N-S-14T represented a novel genomic species belonging to the genus Dyella. The polyphasic taxonomic characteristics indicated that the strain N-S-14T represent a novel species of the genus Dyella, for which the name Dyella sedimenti sp. nov. (type strain N-S-14T = CGMCC 1.18717T = KCTC 82384T) is proposed.

Ignatzschineria rhizosphaerae sp. nov. Isolated from Rhizosphere Soil of the Halophyte Kalidium cuspidatum.

A Gram-staining negative, non-motile, aerobic, rod-shaped bacterium, designated strain HR5S32T, was isolated from rhizosphere soil of the halophyte Kalidium cuspidatum, in Tumd Right Banner, Inner Mongolia, northern China. Strain HR5S32T grew at 10-40 °C (optimum 30 °C), pH 6.0-10.0 (optimum pH 9.0), and 0-12% (w/v) NaCl (optimum 2%). It was positive for catalase, methyl red test, Voges-Proskauer test, and nitrate reduction, but negative to oxidase, urease and hydrolysis of Tween 80. The phylogenetic trees based on the 16S rRNA gene sequences and whole genome both showed that strain HR5S32T was most closely related to Ignatzschineria indica FFA1T (= KCTC 22643 T). Ubiquinone-8 (Q-8) was the major respiratory quinone. Phosphatidylglycerol, phosphatidylethanolamine, and phospholipid were the major polar lipids. Its major fatty acids were Summed features 8 (C18:1 ω6c and/or C18:1 ω7c), C16:0, Summed features 3 (C16:1ω6c and/or C16:1 ω7c), and C14:0. The genome consisted of a 3,074,733 bp circular chromosome, with a G + C content of 38.8%, predicting 2,763 coding sequence genes, 70 tRNA genes and 6 rRNA. The values of the average nucleotide identities (ANI) and digital DNA-DNA hybridization (dDDH) values of strain HR5S32T to I. indica FFA1T were 74.6% and 22.0%, respectively, hence significantly lower than the thresholds of 95% for ANI and 70% for DDH for species delineation. The results of phenotypic, physiological, genotypic, and phylogenetic tests allowed the differentiation of strain HR5S32T from its closely related species. Ignatzschineria rhizosphaerae sp. nov. is therefore proposed, and the type strain is HR5S32T (= CGMCC 1.19435 T = KCTC 92093 T).

Biochemical Characterization of the Subclass B3 Metallo-ß-Lactamase PJM-1 from Pseudoxanthomonas japonensis.

Biochemical properties of the novel subclass B3 metallo-ß-lactamase (MBL) PJM-1 expressed in Pseudoxanthomonas japonensis, which is often isolated from the environment, were determined. The 906-bp blaPJM-1 gene in P. japonensis is a species-specific MBL gene, and PJM, with 301 predicted amino acids, has 81.8% amino acid identity with AIM-1. In this study, PJM-1 was recombinantly expressed and purified. PJM-1 showed a low catalytic activity against ceftazidime and cefepime, and it was strongly inhibited by EDTA.

Isolation and Characterization of the Lytic Pseudoxanthomonas kaohsiungensi Phage PW916.

The emergence of multidrug-resistant bacterial pathogens poses a serious global health threat. While patient infections by the opportunistic human pathogen Pseudoxanthomonas spp. have been increasingly reported worldwide, no phage associated with this bacterial genus has yet been isolated and reported. In this study, we isolated and characterized the novel phage PW916 to subsequently be used to lyse the multidrug-resistant Pseudoxanthomonas kaohsiungensi which was isolated from soil samples obtained from Chongqing, China. We studied the morphological features, thermal stability, pH stability, optimal multiplicity of infection, and genomic sequence of phage PW916. Transmission electron microscopy revealed the morphology of PW916 and indicated it to belong to the Siphoviridae family, with the morphological characteristics of a rounded head and a long noncontractile tail. The optimal multiplicity of infection of PW916 was 0.1. Moreover, PW916 was found to be stable under a wide range of temperatures (4-60 °C), pH (4-11) as well as treatment with 1% (v/w) chloroform. The genome of PW916 was determined to be a circular double-stranded structure with a length of 47,760 bp, containing 64 open reading frames that encoded functional and structural proteins, while no antibiotic resistance nor virulence factor genes were detected. The genomic sequencing and phylogenetic tree analysis showed that PW916 was a novel phage belonging to the Siphoviridae family that was closely related to the Stenotrophomonas phage. This is the first study to identify a novel phage infecting the multidrug-resistant P. kaohsiungensi and the findings provide insight into the potential application of PW916 in future phage therapies.

Physiological and genomic characterisation of Luteimonas fraxinea sp. nov., a bacterial species associated with trees tolerant to ash dieback.

A group of isolates of the genus Luteimonas was characterised, which represented a specific component of the healthy core microbiome of Fraxinus excelsior in forest districts with a high infection rate of H. fraxineus, the causal agent of ash dieback. Based on phylogenomic and phenotypic analyses, a clear differentiation from related Luteimonas species was shown. Comparisons of the overall genome relatedness indices with the closest phylogenetic neighbours resulted in values below the recommended species cut-off levels. In addition, differences in several physiological and chemotaxonomic traits allowed a clear demarcation from the type strains of closely related species. Conclusively, the strain group was considered to represent a novel species in the genus Luteimonas, for which the name Luteimonas fraxinea sp. nov. is proposed, with strain D4P002T (=DSM 113273T = LMG 32455T) as the type strain. A functional analysis of the genome revealed features particularly associated with attachment, biofilm production and motility, indicating the ability of D4P002T to effectively colonise ash leaves. In nursery trials, ash seedlings inoculated with this strain showed suppression of the pathogen over a period of three years. This effect was accompanied by a significant shift in the bacterial microbiome of the plants. Altogether, the exclusive occurrence in the microbiome of tolerant ash trees, the genetic background and the results of the inoculation experiment suggest that strain D4P002T may suppress the penetration and spreading of H. fraxineus in or on ash leaves via colonisation resistance or trigger a priming effect of plant defences against the pathogen.

Novel indole-mediated potassium ion import system confers a survival advantage to the Xanthomonadaceae family.

Interspecific and intraspecific communication systems of microorganisms are involved in the regulation of various stress responses in microbial communities. Although the significance of signaling molecules in the ubiquitous family Xanthomonadaceae has been reported, the role bacterial communications play and their internal mechanisms are largely unknown. Here, we use Lysobacter enzymogenes, a member of Xanthomonadaceae, to identify a novel potassium ion import system, LeKdpXFABC. This import system participates in the indole-mediated interspecies signaling pathway and matters in environmental adaptation. Compared with the previously reported kdpFABC of Escherichia coli, LekdpXFABC contains a novel indispensable gene LekdpX and is directly regulated by the indole-related two-component system QseC/B. QseC autophosphorylation is involved in this process. The operon LekdpXFABC widely exists in Xanthomonadaceae. Moreover, indole promotes antimicrobial product production at the early exponential phase. Further analyses show that indole enhances potassium ion adsorption on the cell surface by upregulating the production of O-antigenic polysaccharides. Finally, we confirm that LeKdpXFABC mediation by indole is subject to the intraspecific signaling molecules DSFs, of which the biosynthesis genes always exist together with LekdpXFABC. Therefore, as a new idea, the signal collaborative strategy of indole and DSFs might ensure the persistent fitness advantage of Xanthomonadaceae in variable environments.

Transcriptional Profiles of a Foliar Fungal Endophyte (Pestalotiopsis, Ascomycota) and Its Bacterial Symbiont (Luteibacter, Gammaproteobacteria) Reveal Sulfur Exchange and Growth Regulation during Early Phases of Symbiotic Interaction.

Symbiosis with bacteria is widespread among eukaryotes, including fungi. Bacteria that live within fungal mycelia (endohyphal bacteria) occur in many plant-associated fungi, including diverse Mucoromycota and Dikarya. Pestalotiopsis sp. strain 9143 is a filamentous ascomycete isolated originally as a foliar endophyte of Platycladus orientalis (Cupressaceae). It is infected naturally with the endohyphal bacterium Luteibacter sp. strain 9143, which influences auxin and enzyme production by its fungal host. Previous studies have used transcriptomics to examine similar symbioses between endohyphal bacteria and root-associated fungi such as arbuscular mycorrhizal fungi and plant pathogens. However, currently there are no gene expression studies of endohyphal bacteria of Ascomycota, the most species-rich fungal phylum. To begin to understand such symbioses, we developed methods for assessing gene expression by Pestalotiopsis sp. and Luteibacter sp. when grown in coculture and when each was grown axenically. Our assays showed that the density of Luteibacter sp. in coculture was greater than in axenic culture, but the opposite was true for Pestalotiopsis sp. Dual-transcriptome sequencing (RNA-seq) data demonstrate that growing in coculture modulates developmental and metabolic processes in both the fungus and bacterium, potentially through changes in the balance of organic sulfur via methionine acquisition. Our analyses also suggest an unexpected, potential role of the bacterial type VI secretion system in symbiosis establishment, expanding current understanding of the scope and dynamics of fungal-bacterial symbioses. IMPORTANCE Interactions between microbes and their hosts have important outcomes for host and environmental health. Foliar fungal endophytes that infect healthy plants can harbor facultative endosymbionts called endohyphal bacteria, which can influence the outcome of plant-fungus interactions. These bacterial-fungal interactions can be influential but are poorly understood, particularly from a transcriptome perspective. Here, we report on a comparative, dual-RNA-seq study examining the gene expression patterns of a foliar fungal endophyte and a facultative endohyphal bacterium when cultured together versus separately. Our findings support a role for the fungus in providing organic sulfur to the bacterium, potentially through methionine acquisition, and the potential involvement of a bacterial type VI secretion system in symbiosis establishment. This work adds to the growing body of literature characterizing endohyphal bacterial-fungal interactions, with a focus on a model facultative bacterial-fungal symbiosis in two species-rich lineages, the Ascomycota and Proteobacteria.

Evidence for Pseudoxanthomonas mexicana as the recent origin of the blaAIM-1 carbapenemase gene.

OBJECTIVES: Elucidating the recent evolutionary history of clinically important antibiotic resistance genes may inform measures to delay the future emergence of additional resistance genes in clinics. This study investigated the recent origin of blaAIM-1, a metallo-ß-lactamase gene found in Pseudomonas aeruginosa, and the possible role of ISCR15 in its mobilisation and transfer into clinical species. METHODS: Comparative genomics were used to identify the recent origin of blaAIM. Mobilisation attempts were performed under different conditions by cloning ISCR15 and the blaAIM-1-like gene in Escherichia coli. RESULTS: Several blaAIM-1 homologues were identified in the Pseudoxanthomonas genus, with conserved synteny of the locus between species and absence of elements associated with mobility. The closest AIM-1 homologue (97.7% amino acid identity) was found in a Pseudoxanthomonas mexicana (P. mexicana) strain. Cloning the blaAIM-like gene in Escherichia coli resulted in high resistance towards carbapenems. While blaAIM-1 is surrounded by ISCR15 elements in clinical strains, in vitro experiments failed to demonstrate their role as mobilising elements. CONCLUSIONS: This study presents evidence that P. mexicana, an environmental species occasionally associated with infections, is the origin of the B3 metallo-ß-lactamase AIM-1. The presence of terIS, a plausible recognition site for ISCR15, in other parts of the P. mexicana genome suggests a more complex and yet not understood mobilisation mechanism.

Class 1 In-Tn5393c array contributed to antibiotic resistance of non-pathogenic Pseudoxanthomonas mexicana isolated from a wastewater bioreactor treating streptomycin.

The emergence of antibiotic resistance in retort to environmental pollutants during wastewater treatment still remains elusive. Here, we first to investigate the emergence of antibiotic resistance in an environmental non-pathogenic bacterium, Pseudoxanthomonas mexicana isolated from a lab-scale bioreactor treating wastewater containing streptomycin. The molecular mechanism of antibiotic resistance development was evaluated in its genomic, transcriptional, and proteomic levels. The streptomycin resistant (SR) strain showed strong resistance to streptomycin (MIC > 600 µg/mL) as well to sulfamethoxazole, ampicillin, and kanamycin (≥250 µg/mL). A 13.4 kb class-1-integron array consisting of a new arrangement of gene cassette (IS6100-sul1-aadA2-catB3-aacA1-2-aadB-int1-IS256-int) linked with Tn5393c transposon was identified in the SR strain, which has only been reported in clinical pathogens so far. iTRAQ-LC-MS/MS proteomics revealed 22 up-regulated proteins in the SR strain growing under 100 mg L-1 streptomycin, involving antibiotic resistance, toxin production, stress response, and ribosomal protein synthesis. At the mRNA level, elevated expressions of ARGs (strA, strB, and aadB) and 30S-ribosomal protein genes (rpsA and rpsU) were observed in the SR strain. The results highlighted the genomic plasticity and multifaceted regulatory mechanism employed by P. mexicana in adaptation to high-level streptomycin during biological wastewater treatment.

Comparative Genomic Analysis of Pseudoxanthomonas sp. X-1, a Bromoxynil Octanoate-Degrading Bacterium, and Its Related Type Strains.

Most Pseudoxanthomonas species described have been derived from water, plants, or contaminated soils. Here, a strain Pseudoxanthomonas sp. X-1 isolated from bromoxynil octanoate (BO)-contaminated soil is presented. Strain X-1 could degrade BO and produce bromoxynil. The optimal conditions for degradation of BO by strain X-1 were an initial BO concentration of 0.1 mM, 30 °C, pH 7, and Mn2+ concentration of 1.0 mM. The bacterial morphological, physiological, and biochemical characteristics of strain X-1 were described, which showed differences comparing with other related type strains. The genome of strain X-1 was sequenced, and a comparative genomic analysis of X-1 and other Pseudoxanthomonas species was conducted to explore the mechanisms underlying the differences among these strains. The genome of strain X-1 encodes 4160 genes, 4078 of which are protein-coding genes and 68 are RNA coding genes. Specifically, strain X-1 encodes enzymes belonging to 778 Enzyme Commission (EC) numbers, much more than those of other related strains, and 62 of them are unique. Eight genes coding esterase are detected in strain X-1 which leads to the ability of BO degradation. This study provides strain, enzyme, and genome resources for the microbial remediation of environments polluted by herbicide BO.

Pseudomarimonas arenosa gen. nov., sp. nov. isolated from marine sand.

A novel Gram-negative, aerobic, non-motile, rod-shaped, bacterial strain (CAU 1598T) was isolated from marine sand. Strain CAU 1598T grew well at 30 °C, pH 6.5-7.0 and with 3 % NaCl (w/v). Phylogeny results based on 16S rRNA gene sequencing indicated that the identified strain had the highest similarity (94.3%) to Pseudoxanthomonas putridarboris, indicating that strain CAU 1598T belongs to the family Xanthomonadaceae. Further, the fatty acid profile of the strain was primarily composed of C16:0, iso-C15 : 0, iso-C16 : 0, summed feature 3 (consisting of C16 : 1 ω7c/iso-C15 : 0 2-OH) and summed feature 9 (consisting of iso-C17 : 1 ω9c and/or C16 : 0 10-methyl), with ubiquinone-8 as the major isoprenoid quinone. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphoglycolipid, an unidentified aminolipid and an unidentified lipid. The G+C content of the bacterial genome was 62.6 mol% and its 5.4 Mb length encompassed 144 contigs and 4236 protein-coding genes. These phenotypic, chemotaxonomic and phylogenetic data indicate that CAU 1598T belongs to a new genus and species, for which the name Pseudomarimonas arenosa gen. nov., sp. nov. is proposed. The type strain is CAU 1598T (=KCTC 82406T=MCCC 1K05673T).