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Methyl-tert-butyl ether (MTBE) and its degradation by-product, tert-butyl alcohol (TBA), are widespread contaminants detected frequently in groundwater in California. Since MTBE was used as a fuel oxygenate for almost two decades, leaking underground fuel storage tanks are an important source of contamination. Gasoline components such as BTEX (benzene, toluene, ethylbenzene and xylenes) are often present in mixtures with MTBE and TBA. Investigations of interactions between BTEX and MTBE degradation have not yielded consistent trends, and the molecular mechanisms of BTEX compounds' impact on MTBE degradation are not well understood. We investigated trends in transcription of biodegradation genes in the MTBE-degrading bacterium, Methylibium petroleiphilum PM1 upon exposure to MTBE, TBA, ethylbenzene and benzene as individual compounds or in mixtures. We designed real-time quantitative PCR assays to target functional genes of strain PM1 and provide evidence for induction of genes mdpA (MTBE monooxygenase), mdpJ (TBA hydroxylase) and bmoA (benzene monooxygenase) in response to MTBE, TBA and benzene, respectively. Delayed induction of mdpA and mdpJ transcription occurred with mixtures of benzene and MTBE or TBA, respectively. bmoA transcription was similar in the presence of MTBE or TBA with benzene as in their absence. Our results also indicate that ethylbenzene, previously proposed as an inhibitor of MTBE degradation in some bacteria, inhibits transcription of mdpA, mdpJ and bmoAgenes in strain PM1.

The article is an editorial from the journal Frontiers in Microbiology, discussing the contributions of women in the field of antimicrobials, resistance, and chemotherapy. It highlights the historical undervaluation of women's achievements in STEM fields and the intersection of gender and antimicrobial resistance. The article also mentions the papers published in the journal's research topic, which shed light on the work of female researchers in addressing antimicrobial resistance. The topics covered in these papers include the evolution of bacterial virulence, effects of HDAC6 inhibitors on bacterial clearance, activity of antibiotics on resistance selection, and the antibacterial activity of novel combinations of b-lactam-b-lactamase inhibitors. Other topics include changes in gut microbiota after antibiotic treatment, the combination of DNase I enzyme with antimicrobial photodynamic therapy, green synthesis of silver nanoparticles for antifungal activity, and appropriate practices in drug administration for animal African trypanosomiasis. The article concludes by emphasizing the importance of diverse perspectives in tackling antimicrobial resistance. [Extracted from the article]

Among the few bacteria known to utilize methyl tert-butyl ether (MTBE) as a sole carbon source, Methylibium petroleiphilum PM1 is a well-characterized organism with a sequenced genome; however, knowledge of the genetic regulation of its MTBE degradation pathway is limited. We investigated the role of a putative transcriptional activator gene, mdpC, in the induction of MTBE-degradation genes mdpA (encoding MTBE monooxygenase) and mdpJ (encoding tert-butyl alcohol hydroxylase) of strain PM1 in a gene-knockout mutant mdpC(-). We also utilized quantitative reverse transcriptase PCR assays targeting genes mdpA, mdpJ and mdpC to determine the effects of the mutation on transcription of these genes. Our results indicate that gene mdpC is involved in the induction of both mdpA and mdpJ in response to MTBE and tert-butyl alcohol (TBA) exposure in PM1. An additional independent mechanism may be involved in the induction of mdpJ in the presence of TBA.

Some members of Burkholderiales are able to grow on methanol but lack the genes (mxaFI) responsible for the well-characterized two-subunit pyrroloquinoline quinone-dependent quinoprotein methanol dehydrogenase that is widespread in methylotrophic Proteobacteria. Here, we characterized novel, mono-subunit enzymes responsible for methanol oxidation in four strains, Methyloversatilis universalis FAM5, Methylibium petroleiphilum PM1, and unclassified Burkholderiales strains RZ18-153 and FAM1. The enzyme from M. universalis FAM5 was partially purified and subjected to matrix-assisted laser desorption ionization-time of fight peptide mass fingerprinting. The resulting peptide spectrum was used to identify a gene candidate in the genome of M. petroleiphilum PM1 (mdh2) predicted to encode a type I alcohol dehydrogenase related to the characterized methanol dehydrogenase large subunits but at less than 35% amino acid identity. Homologs of mdh2 were amplified from M. universalis FAM5 and strains RZ18-153 and FAM1, and mutants lacking mdh2 were generated in three of the organisms. These mutants lost their ability to grow on methanol and ethanol, demonstrating that mdh2 is responsible for oxidation of both substrates. Our findings have implications for environmental detection of methylotrophy and indicate that this ability is widespread beyond populations possessing mxaF, the gene traditionally used as a genetic marker for environmental detection of methanol-oxidizing capability. Our findings also have implications for understanding the evolution of methanol oxidation, suggesting a convergence toward the enzymatic function for methanol oxidation in MxaF and Mdh2-type proteins.

Methylibium petroleiphilum PM1 is a methylotroph distinguished by its ability to completely metabolize the fuel oxygenate methyl tert-butyl ether (MTBE). Strain PM1 also degrades aromatic (benzene, toluene, and xylene) and straight-chain ([C.sub.5] to [C.sub.12]) hydrocarbons present in petroleum products. Whole-genome analysis of PM1 revealed an ~4-Mb circular chromosome and an ~600-kb megaplasmid, containing 3,831 and 646 genes, respectively. Aromatic hydrocarbon and alkane degradation, metal resistance, and methylotrophy are encoded on the chromosome. The megaplasmid contains an unusual t-RNA island, numerous insertion sequences, and large repeated elements, including a 40-kb region also present on the chromosome and a 29-kb tandem repeat encoding phosphonate transport and cobalamin biosynthesis. The megaplasmid also codes for alkane degradation and was shown to play an essential role in MTBE degradation through plasmid-curing experiments. Discrepancies between the insertion sequence element distribution patterns, the distributions of best BLASTP hits among major phylogenetic groups, and the G+C contents of the chromosome (69.2%) and plasmid (66%), together with comparative genome hybridization experiments, suggest that the plasmid was recently acquired and apparently carries the genetic information responsible for PMI's ability to degrade MTBE. Comparative genomic hybridization analysis with two PM1-like MTBE-degrading environmental isolates (~99% identical 16S rRNA gene sequences) showed that the plasmid was highly conserved (ca. 99% identical), whereas the chromosomes were too diverse to conduct resequencing analysis. PM1's genome sequence provides a foundation for investigating MTBE biodegradation and exploring the genetic regulation of multiple biodegradation pathways in M. petroleiphilum and other MTBE-degrading beta-proteobacteria.

Ammonium oxidation by autotrophic ammonia oxidizing bacteria (AOB) is an important process in agricultural systems and nitrite. A real-time PCR assay was developed to estimate the AOB population size in soil and results were recorded.

Researchers were able to quantify a methyl tert-butyl ether (MTBE)-degrading bacterial strain called PM1 in culture, groundwater, and sediment using TaqMan PCR. The bacterium belongs to the Rubrivivax gelatinosus subgroup of the beta-Proteobacteria.

Aim: To determine the impact of an acute, pulse disturbance of nutrients from manure on freshwater sediment microbiomes in an experimental system. Methods and Results: A controlled freshwater mesocosm experiment was designed to compare the effect of disturbance from nutrients derived from sterile manure (SM), disturbance from equivalent concentrations of laboratory‐derived nutrients, and a nondisturbed control on freshwater sediment microbial community composition and function using 16S rRNA amplicon sequencing. Sediment microbiomes impacted by nutrients from SM showed no sign of compositional recovery after 28 days but those impacted by laboratory‐derived chemicals lead to a new steady‐state (p < 0.05). Carbon and nitrate sources within disturbed mesocosms were the primary drivers of altered microbial community composition. Additionally, multiple potential pathogens (based on exact sequence matching at the species level) were enriched in mesocosms treated with SM. Conclusions: Nutrient disturbance from SM, in the absence of the manure microbial community, alters the microbiome of sediments without recovery after 28 days and enriches potential pathogens. Significance and Impact of the Study: These results suggest manure land application practices should be re‐evaluated to account for impact of nutrient disturbance on environmental microbiomes in addition to the impact of the manure microbial community. [ABSTRACT FROM AUTHOR]

A molecular genetic system for Methylibium petroleiphilum PM1 is developed to demonstrate the involvement of enzyme MdpA in methyl tert-butyl ether (MTBE) removal. The results showed that MTBE-induced MdpA, constitutively expressed at low levels is involved in the regulation of tert-butyl alcohol (TBA) removal under certain conditions but is not directly responsible for TBA degradation.

The designing of pcrA gene based real-time quantitative PCR assay for detection of perchlorate-reducing bacteria in soil microbial communities is described. Partial sequencing of pcrA gene showed differences in the composition of perchlorate-reducing bacterial communities when exposed to various electron donors.

High-density whole-genome cDNA microarrays are used for examining substrate-dependent gene expression of Methylibium petroleiphilum PM1, one of the aerobic methyl tert-butyl ether (MTBE)-degrading bacteria. The analysis has predicted several unknown enzymes of the upper MTBE degradation pathway in Methylibium petroleiphilum PM1 and the regulation of metabolic processes that might occur in response to pollutant mixtures and perturbations in the environment.

Copper oxide nanoparticles (CuO NPs) are used increasingly in industrial applications and consumer products and thus may pose risk to human and environmental health. The interaction of CuO NPs with complex media and the impact on cell metabolism when exposed to sublethal concentrations are largely unknown. In the present study, the short-term effects of 2 different sized manufactured CuO NPs on metabolic activity of Saccharomyces cerevisiae were studied. The role of released Cu2þ during dissolution of NPs in the growth media and the CuO nanostructure were considered. Characterization showed that the 28 nm and 64 nm CuO NPs used in the present study have different primary diameter, similar hydrodynamic diameter, and significantly different concentrations of dissolved Cu2þ ions in the growth media released from the same initial NP mass. Exposures to CuO NPs or the released Cu2þ fraction, at doses that do not have impact on cell viability, showed significant inhibition on S. cerevisiae cellular metabolic activity. A greater CuO NP effect on the metabolic activity of S. cerevisiae growth under respiring conditions was observed. Under the tested conditions the observed metabolic inhibition from the NPs was not explained fully by the released Cu ions from the dissolving NPs. [ABSTRACT FROM AUTHOR]