Extent and variation of phage-borne bacterial 16S rRNA gene sequences in wastewater environments

Phage metagenomes isolated from wastewater over a 12-month period were analyzed. The results suggested that various strains of Proteobacteria, Bacteroidetes, and other phyla are likely to participate in transduction. The patterns of 16S rRNA sequences found in phage metagenomes did not follow changes in the total bacterial community.

A Bacterial Enrichment Study and Overview of the Extractable Lipids from Paleosols in the Dry Valleys, Antarctica: Implications for Future Mars Reconnaissance

The Dry Valleys of Antarctica are one of the coldest and driest environments on Earth with paleosols in selected areas that date to the emplacement of tills by warm-based ice during the Early Miocene. Cited as an analogue to the martian surface, the ability of the Antarctic environment to support microbial life-forms is a matter of special interest, particularly with the upcoming NASA/ESA 2018 ExoMars mission. Lipid biomarkers were extracted and analyzed by gas chromatography-mass spectrometry to assess sources of organic carbon and evaluate the contribution of microbial species to the organic matter of the paleosols. Paleosol samples from the ice-free Dry Valleys were also subsampled and cultivated in a growth medium from which DNA was extracted with the explicit purpose of the positive identification of bacteria. Several species of bacteria were grown in solution and the genus identified. A similar match of the data to sequenced DNA showed that Alphaproteobacteria, Gamma-proteobacteria, Bacteriodetes, and Actinobacteridae species were cultivated. The results confirm the presence of bacteria within some paleosols, but no assumptions have been made with regard to in situ activity at present. These results underscore the need not only to further investigate Dry Valley cryosols but also to develop reconnaissance strategies to determine whether such likely Earth-like environments on the Red Planet also contain life.

Characteristics and Treatment of Medical Device Related Infections

Medical device related infections are becoming an increasing prevalent area of infectious disease. They can be attributed to a multitude of factors from an increasing elderly population with reduced immunological status to increasing microbial resistance and evolution. Of greatest significance is the failure of standard antimicrobial regimens to eradicate biomaterial-related infections due to the formation of microbial biofilms consisting of extracellular polymeric substances. Biofilms form and thrive at the abiotic device surface where nutrients are more concentrated and symbiotic colonies can be formed. The formation of a biofilm matrix occurs in a series of steps beginning with reversible attachment of bacteria to the surface of the substrate and terminating in dispersion of mature biofilm microcolonies that aim to colonise fresh surfaces high in nutrients. Mature biofilms can resist 10-1000 times the concentrations of standard antibiotic regimens that are required to kill genetically equivalent planktonic forms. The extent of the infection and the pathogen(s) present can be attributed to both the form and location of the device. It is important that preventative measures and treatment strategies relate to combating the causative microorganisms. Preventative measures include: the use of anti-infective biomaterials that can be coated or incorporated with standard or innovative antimicrobials; modified anti-adhesive medical devices; environmental sterilisation protocols and prophylactic drug therapy. Treatment of established infection may require removal of the device or if deemed possible the device may be salvageable through the initiation of antimicrobial therapy. The increasing spectre of antibiotic resistance and medical device related infections are a large and increasing burden on health care systems and the patient’s quality of life and long term prognosis. As an infectious disease it represents one of the most difficult challenges facing modern science and healthcare.

Bacterial dioxygenase- and monooxygenase-catalysed sulfoxidation of benzo[b]thiophenes

Asymmetric heteroatom oxidation of benzo[b]thiophenes to yield the corresponding sulfoxides was catalysed by toluene dioxygenase (TDO), naphthalene dioxygenase (NDO) and styrene monooxygenase (SMO) enzymes present in P. putida mutant and E. coli recombinant whole cells. TDO-catalysed oxidation yielded the relatively unstable benzo[b] thiophene sulfoxide; its dimerization, followed by dehydrogenation, resulted in the isolation of stable tetracyclic sulfoxides as minor products with cis-dihydrodiols being the dominant metabolites. SMO mainly catalysed the formation of enantioenriched benzo[b] thiophene sulfoxide and 2-methyl benzo[b] thiophene sulfoxides which racemized at ambient temperature. The barriers to pyramidal sulfur inversion of 2- and 3-methyl benzo[b] thiophene sulfoxide metabolites, obtained using TDO and NDO as biocatalysts, were found to be ca.: 25-27 kcal mol(-1). The absolute configurations of the benzo[b] thiophene sulfoxides were determined by ECD spectroscopy, X-ray crystallography and stereochemical correlation. A site-directed mutant E. coli strain containing an engineered form of NDO, was found to change the regioselectivity toward preferential oxidation of the thiophene ring rather than the benzene ring.

ENANTIOSELECTIVE BACTERIAL BIOTRANSFORMATION ROUTES TO CIS-DIOL METABOLITES OF MONOSUBSTITUTED BENZENES, NAPHTHALENE AND BENZOCYCLOALKENES OF EITHER ABSOLUTE-CONFIGURATION

Enzyme-catalysed kinetic resolution and asymmetric dihydroxylation routes to enantiopure cis-diol metabolites of arenes and benzocycloalkenes of either absolute configuration have been developed using appropriate strains of the bacterium Pseudomonas putida.

SULFOXIDES OF HIGH ENANTIOPURITY FROM BACTERIAL DIOXYGENASE-CATALYZED OXIDATION

Selected strains of the bacterium Pseudomonas putida (previously shown to effect dioxygenase-catalysed asymmetric cis-dihydroxylation of alkenes) have been found to yield chiral sulfoxides from the corresponding sulfides with a strong preference for the (R)- or (S)-configurations but without evidence of sulfone formation; similar results obtained using an Escherichia coli clone (pKST11, containing the Tod C1 C2 B and A genes encoding toluene dioxygenase from P. putida NCIMB 11767) are again consistent with a stereoselective dioxygenase-catalysed sulfoxidation.

Electrical methods of controlling bacterial adhesion and biofilm on device surfaces.

This review will summarize the significant body of research within the field of electrical methods of controlling the growth of microorganisms. We examine the progress from early work using current to kill bacteria in static fluids to more realistic treatment scenarios such as flow-through systems designed to imitate the human urinary tract. Additionally, the electrical enhancement of biocide and antibiotic efficacy will be examined alongside recent innovations including the biological applications of acoustic energy systems to prevent bacterial surface adherence. Particular attention will be paid to the electrical engineering aspects of previous work, such as electrode composition, quantitative electrical parameters and the conductive medium used. Scrutiny of published systems from an electrical engineering perspective will help to facilitate improved understanding of the methods, devices and mechanisms that have been effective in controlling bacteria, as well as providing insights and strategies to improve the performance of such systems and develop the next generation of antimicrobial bioelectric materials.