Saccharobipyrimicin, a new antibiotic from the leaf-litter actinomycete Saccharothrix sp. MM696L-181F4.

In the course of screening for new antimicrobial compounds, a new antibiotic substance named saccharobipyrimicin was isolated from the leaf-litter actinomycete Saccharothrix sp. MM696L-181F4. The structure of saccharobipyrimicin was elucidated by various spectral methods, mainly single-crystal X-ray analysis and chemical degradation. It revealed that saccharobipyrimicin contained a 2,2'-bipyridine skeletal structure. Saccharobipyrimicin showed moderate and broad-spectrum antimicrobial activity. Two chemical derivatives of saccharobipyrimicin showed weaker antimicrobial activities than that of saccharobipyrimicin against most test microorganisms except two tolC mutants of Escherichia coli and Neisseria gonorrhoeae.

Celiac disease serology and gut microbiome following proton pump inhibitor treatment.

BACKGROUND: Celiac disease is an autoimmune enteropathy characterized by an aberrant immune response to ingested gluten in genetically predisposed individuals. Studies have pointed to a rising prevalence of celiac disease in recent decades. Changes in diet and use of medication that may impact the gut microbiome have been suggested as potential contributors. Exposure to proton pump inhibitors (PPIs) was recently found to be associated with an increased risk for subsequent diagnosis of celiac disease. We aimed to investigate potential mechanisms for this link by examining the relationship between PPI use and gluten-related immune responses in the context of changes in gut microbiome. METHODS: We performed a post hoc analysis of blood and fecal samples from a recent randomized trial in order to assess the potential association between PPI use and development of celiac disease serology in conjunction with alterations in gastrointestinal microbial composition. The study included 12 healthy participants who were administered a PPI (Omeprazole; 40 mg twice daily) for 4 or 8 weeks. RESULTS: The analysis did not reveal an overall significant change in levels of serologic markers of celiac disease for the study cohort in response to PPI treatment. However, one individual developed a marked increase in the celiac disease-specific autoantibody response to transglutaminase 2 in conjunction with enhanced immune reactivity to gluten during the trial. Genotyping revealed positivity for the celiac disease-associated HLA-DQ2 and -DQ8 alleles. Furthermore, the observed elevation in antibody responses was closely associated with a sharp increase in fecal abundance of bacteria of the order Actinomycetales. CONCLUSIONS: The results of this exploratory analysis support further investigation of molecular mechanisms involved in the contribution of PPIs to celiac disease risk through the potential enhancement of gluten immunopathology and changes in gut microbial population.

Enrichment of novel Actinomycetales and the detection of monooxygenases during aerobic 1,4-dioxane biodegradation with uncontaminated and contaminated inocula.

1,4-Dioxane, a co-contaminant at many chlorinated solvent sites, is a problematic groundwater pollutant because of risks to human health and characteristics which make remediation challenging. In situ 1,4-dioxane bioremediation has recently been shown to be an effective remediation strategy. However, the presence/abundance of 1,4-dioxane degrading species across different environmental samples is generally unknown. Here, the objectives were to identify which 1,4-dioxane degrading functional genes are present and which genera may be using 1,4-dioxane and/or metabolites to support growth across different microbial communities. For this, laboratory sample microcosms and abiotic control microcosms (containing media) were inoculated with four uncontaminated soils and sediments from two contaminated sites. Live control microcosms were treated in the same manner, except 1,4-dioxane was not added. 1,4-Dioxane decreased in live microcosms with all six inocula, but not in the abiotic controls, suggesting biodegradation occurred. A comparison of live sample microcosms and live controls (no 1,4-dioxane) indicated nineteen genera were enriched following exposure to 1,4-dioxane, suggesting a growth benefit for 1,4-dioxane biodegradation. The three most enriched were Mycobacterium, Nocardioides, and Kribbella (classifying as Actinomycetales). There was also a higher level of enrichment for Arthrobacter, Nocardia, and Gordonia (all three classifying as Actinomycetales) in one soil, Hyphomicrobium (Rhizobiales) in another soil, Clavibacter (Actinomycetales) and Bartonella (Rhizobiales) in another soil, and Chelativorans (Rhizobiales) in another soil. Although Arthrobacter, Mycobacterium, and Nocardia have previously been linked to 1,4-dioxane degradation, Nocardioides, Gordonia, and Kribbella are potentially novel degraders. The analysis of the functional genes associated with 1,4-dioxane demonstrated three genes were present at higher relative abundance values, including Rhodococcus sp. RR1 prmA, Rhodococcus jostii RHA1 prmA, and Burkholderia cepacia G4 tomA3. Overall, this study provides novel insights into the identity of the multiple genera and functional genes associated with aerobic degradation of 1,4-dioxane in mixed communities.

Utilization of naproxen by Amycolatopsis sp. Poz 14 and detection of the enzymes involved in the degradation metabolic pathway.

The pollution of aquatic environments by drugs is a problem for which scarce research has been conducted in regards of their removal. Amycolatopsis sp. Poz 14 presents the ability to biotransformation naphthalene at high efficiency, therefore, in this work this bacterium was proposed as an assimilator of naproxen and carbamazepine. Growth curves at different concentrations of naproxen and carbamazepine showed that Amycolatopsis sp. Poz 14 is able to utilize these drugs at a concentration of 50 mg L-1 as a source of carbon and energy. At higher concentrations, the bacterial growth was inhibited. The transformation kinetics of naproxen showed the total elimination of the compound in 18 days, but carbamazepine was only eliminated in 19.9%. The supplementation with cometabolites such as yeast extract and naphthalene (structure similar to naproxen) at 50 mg L-1, showed that the yeast extract shortened the naproxen elimination to 6 days and reached a higher global consumption rate compared to the naphthalene cometabolite. The biotransformation of carbamazepine was not improved by the addition of cometabolites. The partial sequencing of the genome of Amycolatopsis sp. Poz 14 detected genes encoding putative enzymes for the degradation of cyclic aromatic compounds and the activities of aromatic monooxygenase, catechol 1,2-dioxygenase and gentisate 1,2-dioxygenase exhibited their involving in the naproxen biodegradation. The HPLC-MS analysis detected the 5-methoxysalicylic acid at the end of the biotransformation kinetics. This work demonstrates that Amycolatopsis sp. Poz 14 utilizes naproxen and transforms it to 5-methoxysalicylic acid which is the initial compound for the catechol and gentisic acid metabolic pathway.

Reduction of hexavalent chromium (VI) by indigenous alkaliphilic and halotolerant Microbacterium sp. M5: comparative studies under growth and nongrowth conditions.

AIMS: To evaluate hexavalent chromium (Cr (VI)) reduction potential of indigenous isolate M5, under growing and nongrowing conditions. METHODS AND RESULTS: Microbacterium sp. M5 was isolated from soil samples collected from a common effluent treatment plant, after enrichment of indigenous microbial diversity in the presence of 200 mg l-1 of Cr (VI). The isolate achieved complete reduction of 400 mg l-1 Cr (VI) supplement to Luria Bertani medium having initial pH of 9·0 after 48 h incubation. Furthermore, the reduction potential of resting and surfactant treated cell membrane compromised cells of M5 was evaluated. The control and biosurfactant treated cells achieved 22·71 ± 0·5% and 40·56 ± 0·5% reduction of 50 mg l-1 Cr (VI) in Tris-HCl buffer, under resting cells conditions. To the best of our knowledge, this is the first report where cells with compromised cell membrane obtained after exposure to biosurfactant have been evaluated for Cr (VI) reduction. CONCLUSION: The Cr (VI) reduction potential of Microbacterium sp. M5 could be effectively exploited for treatment of chromium-rich effluents, under nongrowing conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The isolate M5 could be a potential inoculum for effluent treatment plants as it is able to support Cr (VI) reduction under wide range of pH, salinity and in the presence of different metal ions.

Blastococcus deserti sp. nov., isolated from a desert sample.

A Gram-positive and aerobic actinobacterium, strain SYSU D8006T, was isolated from a desert sand sample collected from Gurbantunggut desert, China. Phenotypically, the strain was found to grow at 14-50 °C, pH 6.0-9.0 and in the presence of up to 4% (w/v) NaCl. The chemotaxonomic features of strain SYSU D8006T included menaquinone MK-9(H4) as the respiratory quinone, diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside as known polar lipids, iso-C15:0, iso-C16:0, C17:1ω8c and C18:1ω9c as the predominant fatty acids, and arabinose, galactose and glucose as the whole cell sugars. Strain SYSU D8006T shared the highest 16S rRNA gene sequence identity with Blastococcus jejuensis DSM 19597T (98.2%). Based on the analyses of the phenotypic, genotypic and phylogenetic characteristics, strain SYSU D8006T is characterized to represent a novel species of the genus Blastococcus, for which the name Blastococcus deserti sp. nov. is proposed. The type strain is SYSU D8006T (= CGMCC 1.15935T = KCTC 49026T = CPCC 204618T).

Adverse Effect of the Methanotroph Methylocystis sp. M6 on the Non-Methylotroph Microbacterium sp. NM2.

Several non-methylotrophic bacteria have been reported to improve the growth and activity of methanotrophs; however, their interactions remain to be elucidated. We investigated the interaction between Methylocystis sp. M6 and Microbacterium sp. NM2. A batch co-culture experiment showed that NM2 markedly increased the biomass and methane removal of M6. qPCR analysis revealed that NM2 enhanced both the growth and methane-monooxygenase gene expression of M6. A fed-batch experiment showed that co-culture was more efficient in removing methane than M6 alone (28.4 vs. 18.8 µmol·l-1·d-1), although the biomass levels were similar. A starvation experiment for 21 days showed that M6 population remained stable while NM2 population decreased by 66% in co-culture, but the results were opposite in pure cultures, indicating that M6 may cross-feed growth substrates from NM2. These results indicate that M6 apparently had no negative effect on NM2 when M6 actively proliferated with methane. Interestingly, a batch experiment involving a dialysis membrane indicates that physical proximity between NM2 and M6 is required for such biomass and methane removal enhancement. Collectively, the observed interaction is beneficial to the methanotroph but adversely affects the non-methylotroph; moreover, it requires physical proximity, suggesting a tight association between methanotrophs and non-methylotrophs in natural environments.

Complete genome of streamlined marine actinobacterium Pontimonas salivibrio strain CL-TW6T adapted to coastal planktonic lifestyle.

BACKGROUND: Pontimonas salivibrio strain CL-TW6T (=KCCM 90105 = JCM18206) was characterized as the type strain of a new genus within the Actinobacterial family Microbacteriaceae. It was isolated from a coastal marine environment in which members of Microbactericeae have not been previously characterized. RESULTS: The genome of P. salivibrio CL-TW6T was a single chromosome of 1,760,810 bp. Genomes of this small size are typically found in bacteria growing slowly in oligotrophic zones and said to be streamlined. Phylogenetic analysis showed it to represent a lineage originating in the Microbacteriaceae radiation occurring before the snowball Earth glaciations, and to have a closer relationship with some streamlined bacteria known through metagenomic data. Several genomic characteristics typical of streamlined bacteria are found: %G + C is lower than non-streamlined members of the phylum; there are a minimal number of rRNA and tRNA genes, fewer paralogs in most gene families, and only two sigma factors; there is a noticeable absence of some nonessential metabolic pathways, including polyketide synthesis and catabolism of some amino acids. There was no indication of any phage genes or plasmids, however, a system of active insertion elements was present. P. salivibrio appears to be unusual in having polyrhamnose-based cell wall oligosaccharides instead of mycolic acid or teichoic acid-based oligosaccharides. Oddly, it conducts sulfate assimilation apparently for sulfating cell wall components, but not for synthesizing amino acids. One gene family it has more of, rather than fewer of, are toxin/antitoxin systems, which are thought to down-regulate growth during nutrient deprivation or other stressful conditions. CONCLUSIONS: Because of the relatively small number of paralogs and its relationship to the heavily characterized Mycobacterium tuberculosis, we were able to heavily annotate the genome of P. salivibrio CL-TW6T. Its streamlined status and relationship to streamlined metagenomic constructs makes it an important reference genome for study of the streamlining concept. The final evolutionary trajectory of CL-TW6 T was to adapt to growth in a non-oligotrophic coastal zone. To understand that adaptive process, we give a thorough accounting of gene content, contrasting with both oligotrophic streamlined bacteria and large genome bacteria, and distinguishing between genes derived by vertical and horizontal descent.

Genomic insights into the Agromyces-like symbiont of earthworms and its distribution among host species.

The nephridia (excretory organs) of lumbricid earthworms generally harbor symbiotic bacteria. In the compost worms Eisenia fetida and E. andrei, these comprise Verminephrobacter, Ca. Nephrothrix and an Agromyces-like symbiont. While diversity, transmission, and function of the first two symbionts has been unraveled in recent years, little is known about the biology of the uncultured Agromyces-like symbiont or about its distribution within lumbricid earthworms.In this study, we sequenced a cocoon metagenome of E. andrei and assembled a 96.3% complete genome of the Agromyces-like symbiont, which indicates a heterotrophic and potentially microaerophilic lifestyle. A 16S rRNA gene based survey showed that the Agromyces-like symbiont has a narrow host range (present in 10 out of 51 investigated lumbricid earthworm species) and is likely species-specific or at least specific for groups of closely related host species. The Agromyces-like symbionts form a monophyletic group and feature a reduced genome with AT-bias and very low genome-wide similarity to closely related Agromyces spp. (average amino acid identity of 64%); therefore, we suggest establishing a novel genus for the Agromyces-like symbionts of earthworms, for which we propose the name Candidatus Lumbricidophila, with the specific symbiont of Eisenia andrei as novel species Ca. L. eiseniae.

Amycolatopsis vastitatis sp. nov., an isolate from a high altitude subsurface soil on Cerro Chajnantor, northern Chile.

The taxonomic position of a novel Amycolatopsis strain isolated from a high altitude Atacama Desert subsurface soil was established using a polyphasic approach. The strain, isolate H5T, was shown to have chemical properties typical of members of the genus Amycolatopsis such as meso-diaminopimelic acid as the diamino acid in the cell wall peptidoglycan, arabinose and galactose as diagnostic sugars and MK-9(H4) as the predominant isoprenologue. It also has cultural and morphological properties consistent with its classification in the genus, notably the formation of branching substrate hyphae which fragment into rod-like elements. 16S rRNA gene sequence analyses showed that the strain is closely related to the type strain of Amycolatopsis mediterranei but could be distinguished from this and other related Amycolatopsis strains using a broad range of phenotypic properties. It was separated readily from the type strain of Amycolatopsis balhymycina, its near phylogenetic neighbour, based on multi-locus sequence data, by low average nucleotide identity (92.9%) and in silico DNA/DNA relatedness values (51.3%) calculated from draft genome assemblies. Consequently, the strain is considered to represent a novel species of Amycolatopsis for which the name Amycolatopsis vastitatis sp. nov. is proposed. The type strain is H5T (= NCIMB 14970T = NRRL B-65279T).

Partial Proteome of the Corynetoxin-Producing Gram-Positive Bacterium, Rathayibacter toxicus.

Rathayibacter toxicus is a Gram-positive bacterium that is the causative agent of annual ryegrass toxicity (ARGT), a disease that causes devastating losses in the Australian livestock industry. R. toxicus exhibits a complex life cycle, using the nematode Anguina funesta as a physical vector to carry it up to the seed head of the host plant. ARGT is caused by a tunicamycin-like corynetoxin that is produced in R. toxicus-infected seed galls. We analyzed protein expression in R. toxicus under stationary growth phase conditions to obtain a more complete understanding of the biology of this organism and identify potential targets for immunoassay development. A total of 323 unique proteins were identified, including those with putative roles in secondary metabolism and pathogenicity. The proteome analysis for this complex phytopathogenic Gram-positive bacterium will facilitate in the characterization of proteins necessary for host colonization and toxin production, and assist in the development of diagnostic assays. Data are available via ProteomeXchange with identifier PXD004238.

Complete genome sequence of Tsukamurella sp. MH1: A wide-chain length alkane-degrading actinomycete.

Tsukamurella sp. strain MH1, capable to use a wide range of n-alkanes as the only carbon source, was isolated from petroleum-contaminated soil (Pitești, Romania) and its complete genome was sequenced. The 4,922,396 bp genome contains only one circular chromosome with a G + C content of 71.12%, much higher than the type strains of this genus (68.4%). Based on the 16S rRNA genes sequence similarity, strain MH1 was taxonomically identified as Tsukamurella carboxydivorans. Genome analyses revealed that strain MH1 is harboring only one gene encoding for the alkB-like hydroxylase, arranged in a complete alkane monooxygenase operon. This is the first complete genome of the specie T. carboxydivorans, which will provide insights into the potential of Tsukamurella sp. MH1 and related strains for bioremediation of petroleum hydrocarbons-contaminated sites and into the environmental role of these bacteria.

Bacterial isolates degrading ritalinic acid-human metabolite of neuro enhancer methylphenidate.

The consumption of nootropic drugs has increased tremendously in the last decade, though the studies on their environmental fate are still scarce. Nootropics are bioactive compounds designed to alter human's physiology therefore the adverse effects towards wildlife can be expected. In order to understand their environmental impact, the knowledge on their transformation pathways is necessary. Methylphenidate belongs to the most prescribed neuro-enhancers and is among the most favored smart drugs used in non-medical situations. It is metabolized in human liver and excreted as ritalinic acid. Here, we showed for the first time that ritalinic acid can be biodegraded and used as a sole carbon and nitrogen source by various microbial strains originating from different environmental samples. Five axenic strains were isolated and identified as: Arthrobacter sp. strain MW1, MW2 and MW3, Phycicoccus sp. strain MW4 and Nocardioides sp. strain MW5. Our research provides the first insight into the metabolism of ritalinic acid and suggests that it may differ depending on the strain and growth conditions, especially on availability of nitrogen. The isolates obtained in this study can serve as model organisms in further studies on the catabolism of ritalinic acid and methylphenidate but potentially also other compounds with similar structures. Our findings have important implication for the sewage epidemiology. We demonstrated that ritalinic acid is subject to quick and efficient biodegradation thus its use as a stable biomarker should be reconsidered.

Genomic Analysis of Clavibacter michiganensis Reveals Insight Into Virulence Strategies and Genetic Diversity of a Gram-Positive Bacterial Pathogen.

Clavibacter michiganensis subsp. michiganensis is a gram-positive bacterial pathogen that proliferates in the xylem vessels of tomato, causing bacterial canker disease. In this study, we sequenced and assembled genomes of 11 C. michiganensis subsp. michiganensis strains isolated from infected tomato fields in California as well as five Clavibacter strains that colonize tomato endophytically but are not pathogenic in this host. The analysis of the C. michiganensis subsp. michiganensis genomes supported the monophyletic nature of this pathogen but revealed genetic diversity among strains, consistent with multiple introduction events. Two tomato endophytes that clustered phylogenetically with C. michiganensis strains capable of infecting wheat and pepper and were also able to cause disease in these plants. Plasmid profiles of the California strains were variable and supported the essential role of the pCM1-like plasmid and the CelA cellulase in virulence, whereas the absence of the pCM2-like plasmid in some pathogenic C. michiganensis subsp. michiganensis strains revealed it is not essential. A large number of secreted C. michiganensis subsp. michiganensis proteins were carbohydrate-active enzymes (CAZymes). Glycome profiling revealed that C. michiganensis subsp. michiganensis but not endophytic Clavibacter strains is able to extensively alter tomato cell-wall composition. Two secreted CAZymes found in all C. michiganensis subsp. michiganensis strains, CelA and PelA1, enhanced pathogenicity on tomato. Collectively, these results provide a deeper understanding of C. michiganensis subsp. michiganensis diversity and virulence strategies.

Monitoring the impact of bioaugmentation with a PAH-degrading strain on different soil microbiomes using pyrosequencing.

The effect of bioaugmentation with Sphingobium sp. AM strain on different soils microbiomes, pristine soil (PS), chronically contaminated soil (IPK) and recently contaminated soil (Phe) and their implications in bioremediation efficiency was studied by focusing on the ecology that drives bacterial communities in response to inoculation. AM strain draft genome codifies genes for metabolism of aromatic and aliphatic hydrocarbons. In Phe, the inoculation improved the elimination of phenanthrene during the whole treatment, whereas in IPK no improvement of degradation of any PAH was observed. Through the pyrosequencing analysis, we observed that inoculation managed to increase the richness and diversity in both contaminated microbiomes, therefore, independently of PAH degradation improvement, we observed clues of inoculant establishment, suggesting it may use other resources to survive. On the other hand, the inoculation did not influence the bacterial community of PS. On both contaminated microbiomes, incubation conditions produced a sharp increase on Actinomycetales and Sphingomonadales orders, while inoculation caused a relative decline of Actinomycetales. Inoculation of most diverse microbiomes, PS and Phe, produced a coupled increase of Sphingomonadales, Burkholderiales and Rhizobiales orders, although it may exist a synergy between those genera; our results suggest that this would not be directly related to PAH degradation.

Extraction and Analysis of Peptidoglycan Cell Wall Precursors.

Extraction and analysis by LC-MS of peptidoglycan precursors represent a valuable method to study antibiotic mode of action and resistance in bacteria. Here, we describe how to apply this method for: (1) testing the action of different classes of antibiotics inhibiting cell wall biosynthesis in Bacillus megaterium; (2) studying the mechanism of self-resistance in mycelial actinomycetes producing glycopeptide antibiotics.

Long-term ferrocyanide application via deicing salts promotes the establishment of Actinomycetales assimilating ferrocyanide-derived carbon in soil.

Cyanides are highly toxic and produced by various microorganisms as defence strategy or to increase their competitiveness. As degradation is the most efficient way of detoxification, some microbes developed the capability to use cyanides as carbon and nitrogen source. However, it is not clear if this potential also helps to lower cyanide concentrations in roadside soils where deicing salt application leads to significant inputs of ferrocyanide. The question remains if biodegradation in soils can occur without previous photolysis. By conducting a microcosm experiment using soils with/without pre-exposition to road salts spiked with (13) C-labelled ferrocyanide, we were able to confirm biodegradation and in parallel to identify bacteria using ferrocyanide as C source via DNA stable isotope probing (DNA-SIP), TRFLP fingerprinting and pyrosequencing. Bacteria assimilating (13) C were highly similar in the pre-exposed soils, belonging mostly to Actinomycetales (Kineosporia, Mycobacterium, Micromonosporaceae). In the soil without pre-exposition, bacteria belonging to Acidobacteria (Gp3, Gp4, Gp6), Gemmatimonadetes (Gemmatimonas) and Gammaproteobacteria (Thermomonas, Xanthomonadaceae) used ferrocyanide as C source but not the present Actinomycetales. This indicated that (i) various bacteria are able to assimilate ferrocyanide-derived C and (ii) long-term exposition to ferrocyanide applied with deicing salts leads to Actinomycetales outcompeting other microorganisms for the use of ferrocyanide as C source.

Cellulosimicrobium marinum sp. nov., an actinobacterium isolated from sea sediment.

A novel Gram stain positive actinobacterium, designated RS-7-4(T), was isolated from a sea sediment sample collected in Indonesia, and its taxonomic position was investigated using a polyphasic approach. Strain RS-7-4(T) was observed to form vegetative hyphae in the early phase of growth, but the hyphae eventually fragmented into short rods to coccoid cells. Growth occurred at 15-37 °C, pH 6.0-11.0 and in the presence of 0-7 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain RS-7-4(T) was closely related to the members of the genus Cellulosimicrobium, with a similarity range of 98.08-99.10 %. The peptidoglycan type of strain RS-7-4(T) was found to be A4α L-Lys-L-Thr-D-Asp. The predominant menaquinone was MK-9(H4), and the major fatty acids were anteiso-C15:0, iso-C15:0 and anteiso-C17:0. The DNA G+C content was 75.6 mol%. These chemotaxonomic features corresponded to those of the genus Cellulosimicrobium. Meanwhile, the results of DNA-DNA hybridization, and physiological and biochemical tests revealed that strain RS-7-4(T) was different from the recognized species of the genus Cellulosimicrobium. Therefore, strain RS-7-4(T) represents a novel species of the genus Cellulosimicrobium, for which the name Cellulosimicrobium marinum sp. nov. is proposed. The type strain is RS-7-4(T) (=NBRC 110994(T) =InaCC A726(T)).

Culturable endophytic bacteria from the salt marsh plant Halimione portulacoides: phylogenetic diversity, functional characterization, and influence of metal(loid) contamination.

Halimione portulacoides is abundant in salt marshes, accumulates mercury (Hg), and was proposed as useful for phytoremediation and pollution biomonitoring. Endophytic bacteria promote plant growth and provide compounds with industrial applications. Nevertheless, information about endophytic bacteria from H. portulacoides is scarce. Endophytic isolates (n = 665) were obtained from aboveground and belowground plant tissues, from two Hg-contaminated sites (sites E and B) and a noncontaminated site (site C), in the estuary Ria de Aveiro. Representative isolates (n = 467) were identified by 16S rRNA gene sequencing and subjected to functional assays. Isolates affiliated with Proteobacteria (64 %), Actinobacteria (23 %), Firmicutes (10 %), and Bacteroidetes (3 %). Altererythrobacter (7.4 %), Marinilactibacillus (6.4 %), Microbacterium (10.2 %), Salinicola (8.8 %), and Vibrio (7.8 %) were the most abundant genera. Notably, Salinicola (n = 58) were only isolated from site C; Hoeflea (17), Labrenzia (22), and Microbacterium (67) only from belowground tissues. This is the first report of Marinilactibacillus in the endosphere. Principal coordinate analysis showed that community composition changes with the contamination gradient and tissue. Our results suggest that the endosphere of H. portulacoides represents a diverse bacterial hotspot including putative novel species. Many isolates, particularly those affiliated to Altererythrobacter, Marinilactibacillus, Microbacterium, and Vibrio, tested positive for enzymatic activities and plant growth promoters, exposing H. portulacoides as a source of bacteria and compounds with biotechnological applications.

Aeromicrobium halotolerans sp. nov., isolated from desert soil sample.

A Gram-positive, aerobic, and non-motile, rod-shaped actinomycete strain, designated YIM Y47(T), was isolated from soils collected from Turpan desert, China, and subjected to a polyphasic taxonomic study. Phylogenetic analysis indicated that strain YIM Y47(T) belonged to the genus Aeromicrobium. YIM Y47(T) shared highest 16S rRNA gene sequence similarities with Aeromicrobium massiliense JC14(T) (96.47 %). Growth occurs at 20-45 °C (optimum at 30 °C), pH 6.0-8.0 (optimum at pH 7.0), and salinities of 0-7.0 % NaCl (optimum at 4.0 %). The strain YIM Y47(T) exhibits chemotaxonomic features with menaquinone-7 (MK-7) as the predominant quinone, C16:0, C18:1 ω9c and 10-methyl C18:0 (>10 %) as major fatty acids. The cell-wall peptidoglycan of strain YIM Y47(T) contained LL-diaminopimelic acid as the diagnostic diamino acid. The polar lipids were found to consist of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, and unknown phospholipids. The G+C content of the genomic DNA of strain YIM Y47(T) was found to be 44.7 mol%. On the basis of phylogenetic analyses and phenotypic data, it is proposed that strain YIM Y47(T) should be classified as representing a novel species of the genus Aeromicrobium, with the name Aeromicrobium halotolerans sp. nov. The type strain is YIM Y47(T) (=KCTC 39113(T)=CGMCC 1.15063(T)=DSM 29939(T)=JCM 30627(T)).