Phosphate solubilizing bacteria from subtropical soil and their tricalcium phosphate solubilizing abilities

The origin and evolution of photosynthesis have long remained enigmatic due to a lack of sequence information of photosynthesis genes across the entire photosynthetic domain. To probe early evolutionary history of photosynthesis, we obtained new sequence information of a number of photosynthesis genes from the green sulfur bacterium Chlorobium tepidum and the green nonsulfur bacterium Chloroflexus aurantiacus. A total of 31 open reading frames that encode enzymes involved in bacteriochlorophyll/porphyrin biosynthesis, carotenoid biosynthesis, and photosynthetic electron transfer were identified in about 100 kilobase pairs of genomic sequence. Phylogenetic analyses of multiple magnesium-tetrapyrrole biosynthesis genes using a combination of distance, maximum parsimony, and maximum likelihood methods indicate that heliobacteria are closest to the last common ancestor of all oxygenic photosynthetic lineages and that green sulfur bacteria and green nonsulfur bacteria are each other's closest relatives. Parsimony and distance analyses further identify purple bacteria as the earliest emerging photosynthetic lineage. These results challenge previous conclusions based on 16S ribosomal RNA and Hsp60/Hsp70 analyses that green nonsulfur bacteria or heliobacteria are the earliest phototrophs. The overall consensus of our phylogenetic analysis, that bacteriochlorophyll biosynthesis evolved before chlorophyll biosynthesis, also argues against the long-held Granick hypothesis.

https://science.sciencemag.org/content/sci/289/5485/1724.full.pdf

Molecular Evidence for the Early Evolution of Photosynthesis

Signature-tagged mutagenesis with transposon Tn917 was used to identify genes of Staphylococcus aureus required for virulence in a murine model of bacteraemia. Screening 1248 mutant strains in pools of 96 resulted in the provisional identification of 50 mutants attenuated in virulence. Subsequent individual analysis of many of these mutants confirmed that they are attenuated in virulence. DNA sequence analysis of regions flanking their transposon insertion points revealed that approximately half of them represent genes with unknown function, while most of the remainder are involved in nutrient biosynthesis and cell surface metabolism. Three mutants were found with transposon insertions in different positions in femA, and one mutant had an insertion in femB. Both femA and femB are involved in the formation of cell wall peptidoglycan pentaglycine cross-bridges. A further mutation occurred in a previously unknown gene that shares significant similarity to femB. Mutations were also obtained in recA and lsp (encoding the S. aureus prolipoprotein signal peptidase). On the basis of sequence similarities to proteins of known function, the products of other genes are probably involved in the synthesis of diaminopimelic acid (a component of peptidoglycan), maintenance of surface adhesins and cell surface membrane transport, showing that many components of the S. aureus cell surface are critical for the survival and replication of this pathogen in blood.

Identification of Staphylococcus aureus virulence genes in a murine model of bacteraemia using signature-tagged mutagenesis

Recent advances in the social and developmental biology of the myxobacteria.

Exopolysaccharide-Producing Plant Growth-Promoting Rhizobacteria Under Salinity Condition

A versatile quick-prep of genomic DNA from Gram-positive bacteria

Rapid isolation of genomic DNA from gram-negative bacteria.

Genomic DNA of Stigmatella aurantiaca DW 4/3.1 was restricted with the rare-cutting endonucleases AseI and SpeI. The restriction pattern derived is composed of 33 AseI and 25 SpeI fragments, whose total size amounts to approximately 9,350 kbp. Genomic fingerprint analysis of chromosomal DNA from several S. aurantiaca isolates further revealed five completely different SpeI and AseI fingerprints and one distinct fingerprint for Stigmatella erecta. In addition, minor variations between the genome sizes of these isolates were observed.

Size and stability of the genomes of the myxobacteria Stigmatella aurantiaca and Stigmatella erecta.

A physical map of the myxobacterium Stigmatella aurantiaca DW4/3.1 chromosome was constructed by pulsed-field gel (PFG) long-range mapping. One-and two-dimensional pulsed-field gel analyses were used together with reciprocal double-restriction, cross-hybridization and hybridization fingerprint analysis. These PFG results were confirmed by Smith-Birnstiel analysis, by Southern hybridization using linking clones and clones of a lambda genomic library for the determination of adjacent restriction fragments and by transposon insertion mapping using defined genomic sequences for hybridization. It was thus possible to construct a circular restriction map of the single 9.35 Mbp chromosome of S. aurantiaca based on the endonucleases Asel and Spel. Genetic loci as well as the replication origin were located on the physical map by Southern hybridization using heterologous (derived from Myxococcus xanthus, Escherichia coli and Streptomyces lividans) and homologous probes that are mainly involved in development and cell motility.

A physical and genetic map of the Stigmatella aurantiaca DW4/3.1 chromosome

Stigmatella aurantiaca is a prokaryotic organism that undergoes a multicellular cycle of development resulting in the formation of a fruiting body. For analyzing this process, mutants defective in fruiting body formation have been induced by transposon mutagenesis using a Tn5-derived transposon. About 800 bp upstream of the transposon insertion of mutant AP182 which inactivates a gene (fbfB) involved in fruiting, a further gene (fbfA) needed for fruiting body formation was detected. Inactivation of fbfA leads to mutants which form only non-structured clumps instead of the wild-type fruiting body. The mutant phenotype of fbfA mutants can be partially suppressed by mixing the mutant cells with cells of some independent mutants defective in fruiting body formation. The fbfA gene is transcribed after 8 h of development as determined by measuring the induction of beta-galactosidase activity of a fbfA-delta(trp)-lacZ fusion gene and by Northern (RNA) analysis using an insertion encoding a stable mRNA. The predicted polypeptide FbfA shows a homology of about 30% to NodC of rhizobia, an N-acetylglucosamine-transferase which is involved in the synthesis of the sugar backbone of lipo-oligosaccharides. These induce the formation of the root nodules in the Papilionaceae. Besides the predicted molecular mass of 45.5 kDa, the hydropathy profile reveals a structural relationship to the NodC polypeptide.

Andreas Pospiech

Papers

A versatile quick-prep of genomic DNA from Gram-positive bacteria

Rapid isolation of genomic DNA from gram-negative bacteria.

Size and stability of the genomes of the myxobacteria Stigmatella aurantiaca and Stigmatella erecta.

A physical and genetic map of the Stigmatella aurantiaca DW4/3.1 chromosome

Stigmatella aurantiaca fruiting body formation is dependent on the fbfA gene encoding a polypeptide homologous to chitin synthases.