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A study on the discrimination of the stable carbon isotopes by different microorganisms were made to determine whether ratios of carbon isotopes in microbial lipids can be used as indicators of substrate usage. Eleven strains of well known bacterial and fungal species with four different isotopically define carbon sources were grown and their isotope ratios of fatty acids of different lipid fractions were identified. Results show that the isotope ratio does not depend on the growth stage.

A study was conducted to isolate a novel fatty acid from the coryneform bacterial strain LMG 3820. A set of nuclear magnetic resonance data was utilized to determine the nature and substitution patterns of the glycerol moieties. Results indicated that different organisms supporting 16S rDNA sequences accommodate various fatty acid and lipid compositions. Findings also showed that the fatty acid's routine detection is influenced by the equivalent chain number.

High-pressure liquid chromatography was used to monitor N-cyclohexyldiazenium dioxide (HDO) concentration in isotope-labeled ([super 13]C) and nonlabeled ([super 12]C) Cu-HDO incorporated in wood sawdust mixed with soil. Cu-HDO as part of a wood preservative was observed to effectively decrease fungal wood decay and overall microbial respiration from soil.

The spatial and compositional structure and complex dynamics of the developing biofilm and its polychlorinated biphenyls (PCB)-degrading activity, leading to the identification of three stages of biofilm development is reported. The biofilm developing from PCB-contaminated soil on PCB droplets displayed a pronounced pattern of maturation not reported before from pure-culture experiments.

Pseudomonas aeruginosa is distinguished by its broadmetabolic diversity and its remarkable capability for adaptation, which relies on a large collection of transcriptional regulators and alternative sigma (σ) factors. The largest group of alternative σ factors is that of the extracytoplasmic function (ECF) σ factors, which control key transduction pathways for maintenance of envelope homeostasis in response to external stress and cell growth. In addition, there are specific roles of alternative σ factors in regulating the expression of virulence and virulence-associated genes. Here, we analyzed a deletion mutant of the ECF factor SigX and applied mRNA profiling to define the SigX-dependent regulon in P. aeruginosa in response to low-osmolarity-medium conditions. Furthermore, the combination of transcriptional data with chromatin immuno precipitation (ChIP) followed by high-throughput sequencing (ChIP-seq) led to the identification of the DNA binding motif of SigX. Genome-wide mapping of SigX-binding regions revealed enrichment of down stream genes involved in fatty acid biosynthesis, type III secretion, swarming and cyclic di-GMP (c-di-GMP) signaling. In accordance, a sigX deletion mutant exhibited altered fatty acid composition of the cell membrane, reduced cytotoxicity, impaired swarming activity, elevated c-di-GMP levels, and increased biofilm formation. In conclusion, a combination of ChIP-seq with transcriptional profiling and bioinformatic approaches to define consensus DNA binding sequences proved to be effective for the elucidation of the regulon of the alternative σ factor SigX, revealing its role in complex virulence-associated phenotypes in P. aeruginosa. [ABSTRACT FROM AUTHOR]