Cellulomonas phragmiteti sp. nov., a cellulolytic bacterium isolated from reed (Phragmites australis) periphyton in a shallow soda pond.

An alkalitolerant and moderately halophilic strain, designated KB23(T), characterized by optimal growth at pH 8.0-9.0 and in the presence of 5-7 % (w/v) NaCl, was isolated from a reed (Phragmites australis) periphyton sample originating from an extremely shallow, alkaline soda pond located in Hungary. Cells of strain KB23(T) were Gram-stain-positive, motile straight rods. Strain KB23(T) was facultatively anaerobic, catalase-positive, oxidase-negative and contained peptidoglycan type A4ß (L-Orn-D-Asp). MK-9(H4) was the predominant isoprenoid quinone and anteiso-C(15 : 0), C(16 : 0) and anteiso-C(15 : 1) were the major cellular fatty acids. The DNA G+C content of strain KB23(T) was 74.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that this strain belongs to the genus Cellulomonas and that it is related most closely to Cellulomonas flavigena DSM 20109(T) (97.35 % similarity), Cellulomonas terrae DB5(T) (96.81 %), Cellulomonas iranensis O(T) (96.75), Cellulomonas chitinilytica X.bu-b(T) (96.60 %), Cellulomonas persica I(T) (96.53 %), Cellulomonas composti TR7-06(T) (96.45 %), Cellulomonas biazotea DSM 20112(T) (96.34 %) and Cellulomonas fimi DSM 20113(T) (96.20 %). According to these results, together with DNA-DNA hybridization and physiological data, strain KB23(T) is considered to represent a novel species of the genus Cellulomonas, for which the name Cellulomonas phragmiteti sp. nov. is proposed. The type strain is KB23(T) ( = DSM 22512(T)  = NCAIM B002303(T)).

Phylogenetic and metabolic bacterial diversity of Phragmites australis periphyton communities in two Hungarian soda ponds.

Bacterial diversity of reed (Phragmites australis) periphyton communities of Kelemen-szék and Nagy-Vadas (two Hungarian soda ponds) was investigated using molecular cloning and cultivation-based techniques. The majority of the 80 Kelemen-szék and 72 Nagy-Vadas bacterial isolates proved to be moderately halophilic and alkaliphilic. A great proportion of the isolates showed phosphatase and urease activity, utilized aesculin, citrate and certain biopolymers (e.g., gelatine and tween 80). Partial 16S rDNA sequence analysis of 33 Kelemen-szék and 20 Nagy-Vadas ARDRA group representatives showed Gram-positive (Nesterenkonia, Cellulomonas, Dietzia, Bacillus and Planococcus) dominance at both sampling sites. Species of the genera Acidovorax, Hydrogenophaga (beta-Proteobacteria) and Flavobacterium, Sphingobacterium (Bacteroidetes) were represented only from Kelemen-szék. Altogether 16 isolates showed low sequence similarity with yet described bacteria and may represent novel taxa. Screening of the 16S rRNA gene libraries of 129 Kelemen-szék and 158 Nagy-Vadas clones resulted in 30 and 28 different ARDRA groups, respectively. Sequence analysis revealed a Gram-negative (Rheinheimera, Aquimonas, Cellvibrio, Flavobacterium and Sphingobacterium) dominated phylogenetic diversity. A high number of the clones were affiliated with uncultured bacterial clones described from diverse environmental samples.

Diversity of sulfate-reducing bacteria inhabiting the rhizosphere of Phragmites australis in Lake Velencei (Hungary) revealed by a combined cultivation-based and molecular approach.

The community structure of sulfate-reducing bacteria (SRB) associated with reed (Phragmites australis) rhizosphere in Lake Velencei (Hungary) was investigated by using cultivation-based and molecular methods. The cultivation methods were restricted to recover lactate-utilizing species with the exclusion of Desulfobacter and some Desulfobacterium species presumably not being dominant members of the examined community. The most-probable-number (MPN) estimations of lactate-utilizing SRB showed that the cell counts in reed rhizosphere were at least one order of magnitude higher than that in the bulk sediment. The number of endospores was low compared to the total SRB counts. From the highest positive dilution of MPN series, 47 strains were isolated and grouped by restriction fragment length polymorphism (RFLP) analysis of the amplified 16S ribosomal RNA (rRNA) and dsrAB (dissimilatory sulfite reductase) genes. Contrary to the physiological diversity of the isolates, the combined results of RFLP analysis revealed higher diversity at species as well as at subspecies level. Based on the partial 16S rRNA sequences, the representative strains were closely affiliated with the genera Desulfovibrio and Desulfotomaculum. The partial dsrAB sequences of the clones, recovered after isolation and PCR amplification of the community DNA, were related to hitherto uncultured species of the genera Desulfovibrio and Desulfobulbus. Nevertheless, the representative of the second largest clone group was shown to be closely affiliated with the sequenced dsrAB gene of a strain isolated from the same environment and identified as Desulfovibrio alcoholivorans. Another clone sequence was closely related to a possible novel species also isolated within the scope of this work.

Metabolic activity and phylogenetic diversity of reed (Phragmites australis) periphyton bacterial communities in a hungarian shallow soda lake.

In the present study, the species composition and potential metabolic activities of bacterial communities of reed Phragmites australis (Cav.) (Trin. ex Steudel) periphyton from Lake Velencei were studied by cultivation-based and metabolic fingerprinting methods. Serially diluted spring biofilm samples were used to test the community-level physiological profiling (CLPP) using BIOLOG microplates, and for plating onto different media. On the basis of their morphological, biochemical, and physiological test results, 173 strains were clustered by numerical analysis. Representatives of amplified ribosomal DNA restriction analysis (ARDRA) groups were identified by their 16S rDNA sequence comparison. Based on the results of the CLPP investigations, regional differences were detected among the utilized substrate numbers and types, parallel with the increase in incubation time. The phenotypic test results of the strains showed considerable variability with respect to the sampling sites and the media used for cultivation. The most frequently isolated strains were identified as members of genera Agrobacterium, Pseudomonas (P. anguilliseptica, P. marginalis, P. alcaligenes, P. fragi) with aerobic or facultative anaerobic respiratory metabolism, and the species Aeromonas sobria and A. veronii with strong facultative fermentative metabolism. Other strains were identified as Gram-positive Arthrobacter, Bacillus, and Kocuria species. The rarely isolated strains were members of beta-Proteobacteria (Acidovorax, Delftia, Hydrogenophaga, and Rhodoferax), gamma-Proteobacteria (Psychrobacter and Shewanella), low G + C Gram-positives (Brevibacillus, Paenibacillus, and Exiguobacterium) and high G + C Gram-positives (Aureobacterium and Microbacterium).

Chemical and biological characterisation of biofilms formed on different substrata in Tisza river (Hungary).

Natural biofilms were simultaneously grown on granite, polished granite, andesite, polycarbonate and Plexi-glass substrata for six weeks in the Tisza River. Biofilm production and abundance of algae were influenced by the substratum. Magnitude of the substratum effect was andesite