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Studies considering environmental multidrug-resistant Acinetobacter spp. are scarce. The application of manure on agricultural fields is one source of multidrug-resistant bacteria from livestock into the environment. Here, Acinetobacter spp. were quantified by quantitative polymerase chain reaction in manure applied to biogas plants and in the output of the anaerobic digestion, and Acinetobacter spp. isolated from those samples were comprehensively characterized. The concentration of Acinetobacter 16S ribosomal ribonucleic acid (rRNA) gene copies per g fresh weight was in range of 106–108 in manure and decreased (partially significantly) to a still high concentration (105–106) in digestates. 16S rRNA, gyrB-rpoB and bla OXA51-like gene sequencing identified 17 different Acinetobacter spp. including six A. baumannii strains. Multilocus sequence typing showed no close relation of the six strains with globally relevant clonal complexes; however, they represented five novel sequence types. Comparative genomics and physiological tests gave an explanation how Acinetobacter could survive the anaerobic biogas process and indicated copper resistance and the presence of intrinsic beta-lactamases, efflux-pump and virulence genes. However, the A. baumannii strains lacked acquired resistance against carbapenems, colistin and quinolones. This study provided a detailed characterization of Acinetobacter spp. including A. baumannii released via manure through mesophilic or thermophilic biogas plants into the environment. [ABSTRACT FROM AUTHOR]

The leaf-colonizing bacterial microbiota was studied in a long-term warming experiment on a permanent grassland, which had been continuously exposed to increased surface temperature (+2°C) for more than six years. Two abundant plant species, Arrhenatherum elatius and Galium album , were studied. Surface warming reduced stomata opening and changed leaf metabolite profiles. Leaf surface colonization and the concentration of leaf-associated bacterial cells were not affected. However, bacterial 16S ribosomal RNA (rRNA) gene amplicon Illumina sequencing showed significant temperature effects on the plant species-specific phyllosphere microbiota. Warming partially affected the concentrations of cultured bacteria and had a significant effect on the composition of most abundant cultured plant species-specific bacteria. The abundance of Sphingomonas was significantly reduced. Sphingomonas isolates from warmed plots represented different phylotypes, had different physiological traits and were better adapted to higher temperatures. Among Methylobacterium isolates, a novel phylotype with a specific mxaF type was cultured from plants of warmed plots while the most abundant phylotype cultured from control plots was strongly reduced. This study clearly showed a correlation of long-term surface warming with changes in the plant physiology and the development of a physiologically and genetically adapted phyllosphere microbiota. [ABSTRACT FROM AUTHOR]

Vancomycin-resistant enterococci (VRE) and methicillin-resistant staphylococci (MRS) were detected in two mesophilic German biogas plants (BGPs) using selective pre-enrichment methods combined with cultivation on CHROMagar media and antibiotic resistance gene screening. Genetic fingerprinting and 16S rRNA gene sequencing showed the presence of enterococci isolated by the VRE selective cultivation (67 isolates) in input and output samples of BGPs. In contrast, MRS (44 isolates) were detected in input, but in none of the output samples. Enterococcus isolates showed highest 16S rRNA gene sequence similarity (>99.8%) to E. lemanii, E. casseliflavus/E. gallinarium or E. devriesei/E. pseudoavium/E. viikkiensis and carried vanA, vanB and/or vanC1 genes. Enterococcus faecium and E. faecalis VRE were not detected, but isolates closely related to those species (>99.9% 16S rRNA gene sequence similarity) were detected by the MRS selective cultivation methods. Staphylococcus isolates shared highest 16S rRNA gene sequence similarity (>99.9%) with S. haemolyticus, S. lentus and S. sciuri and carried mecA genes. Methicillin-resistant S. aureus (MRSA) were not detected. In summary, manure from livestock husbandry contained both, VRE and MRS. VRE were also detected in output samples, indicating that enterococci with vancomycin resistance genes could be release into the environment by the application of BGP output material as biofertilizers. [ABSTRACT FROM AUTHOR]

Associations of endophytic bacterial community composition of oilseed rape (Brassica napus L.) with quantitative resistance against the soil-borne fungal pathogen Verticillium longisporum was assessed by 16S rRNA gene amplicon sequencing in roots and hypocotyls of four plant lines with contrasting genetic composition in regard to quantitative resistance reactions. The plant compartment was found to be the dominating driving factor for the specificity of bacterial communities in healthy plants. Furthermore, V. longisporum infection triggered a stabilization of phylogenetic group abundance in replicated samples suggesting a host genotype-specific selection. Genotype-specific associations with bacterial phylogenetic group abundance were identified by comparison of plant genotype groups (resistant versus susceptible) and treatment groups (healthy versus V. longisporum -infected) allowing dissection into constitutive and induced directional association patterns. Relative abundance of Flavobacteria , Pseudomonas , Rhizobium and Cellvibrio was associated with resistance/susceptibility. Relative abundance of Flavobacteria and Cellvibrio was increased in resistant genotypes according to their known ecological functions. In contrast, a higher relative abundance of Pseudomonas and Rhizobium , which are known to harbor many species with antagonistic properties to fungal pathogens, was found to be associated with susceptibility, indicating that these groups do not play a major role in genetically controlled resistance of oilseed rape against V. longisporum. [ABSTRACT FROM AUTHOR]