Release of Cell-Free Ice Nucleators from Three Recombinant Ice Zymomonas mobilis Strains.

Background/aims: This work is a study of the ability of three recombinant Zymomonas mobilis strains to release ice nucleators into their growth medium.

Methods: The recombinant ice(+)Z. mobilis cells were tested for their ability to produce cell-free ice nucleators, under three different growth temperatures and three different glucose concentrations.

On the role of the appended P19 element in type A RNAs of bacterial RNase P.

Comparative in silico analyses of bacterial RNase P enzymes clustered their RNA subunits in type A RNA, found in Escherichia coli, and in type B, found in Bacillus subtilis. Zymomonas mobilis RNase P consists of one protein (Zmo-RnpA) and one type A RNA (RPR) subunit containing the P19 element, present in many RNase P RNAs of any structure class but lacking in the E. coli RNase P RNA.

Interaction between relaxase MbeA and accessory protein MbeC of the conjugally mobilizable plasmid ColE1.

MbeA and MbeC are two key proteins in plasmid ColE1 conjugal mobilization. Isothermal titration calorimetry was used to detect and quantify an interaction between MbeA and MbeC. As a result of this interaction, the affinity of MbeA for single stranded DNA increased.

Complete genome sequence of Mycobacterium sp. strain (Spyr1) and reclassification to Mycobacterium gilvum Spyr1.

Mycobacterium sp.Spyr1 is a newly isolated strain that occurs in a creosote contaminated site in Greece. It was isolated by an enrichment method using pyrene as sole carbon and energy source and is capable of degrading a wide range of PAH substrates including pyrene, fluoranthene, fluorene, anthracene and acenapthene.

Heterologous expression and characterization of two 1-hydroxy-2-naphthoic acid dioxygenases from Arthrobacter phenanthrenivorans.

A protein fraction exhibiting 1-hydroxy-2-naphthoic acid (1-H2NA) dioxygenase activity was purified via ion exchange, hydrophobic interactions, and gel filtration chromatography from Arthrobacter phenanthrenivorans sp. nov. strain Sphe3 isolated from a Greek creosote-oil-polluted site.

Complete genome sequence of Arthrobacter phenanthrenivorans type strain (Sphe3).

Arthrobacter phenanthrenivorans is the type species of the genus, and is able to metabolize phenanthrene as a sole source of carbon and energy. A. phenanthrenivorans is an aerobic, non-motile, and Gram-positive bacterium, exhibiting a rod-coccus growth cycle which was originally isolated from a creosote polluted site in Epirus, Greece.

The effect of Debina grapevine indigenous yeast strains of Metschnikowia and Saccharomyces on wine flavour.

The spontaneous alcoholic fermentation of grape must is a complex microbiological process involving a large number of various yeast species, to which the flavour of every traditional wine is largely attributed. Whilst Saccharomyces cerevisiae is primarily responsible for the conversion of sugar to alcohol, the activities of various non-Saccharomyces species enhance wine flavour. In this study, indigenous yeast strains belonging to Metschnikowia pulcherrima var.

Analysis of ColE1 MbeC unveils an extended ribbon-helix-helix family of nicking accessory proteins.

MbeC is a 13-kDa ColE1-encoded protein required for efficient mobilization of ColE1, a plasmid widely used in cloning vector technology. MbeC protein was purified and used for in vitro DNA binding, which showed that it binds specifically double-stranded DNA (dsDNA) containing the ColE1 oriT. Amino acid sequence comparison and secondary structure prediction imply that MbeC is related to the ribbon-helix-helix (RHH) protein family.

Heterologous expression of a hyperthermophilic alpha-amylase in xanthan gum producing Xanthomonas campestris cells.

A hyperthermophilic alpha-amylase encoding gene from Pyrococcus woesei was transferred and expressed in Xanthomonas campestris ATCC 13951. The heterologous alpha-amylase activity was detected in the intracellular fraction of X. campestris and presented similar thermostability and catalytic properties with the native P.

Proton inventories constitute reliable tools in investigating enzymatic mechanisms: application on a novel thermo-stable extracellular protease from a halo-alkalophilic Bacillus sp.

A novel protease designated protease-A-17N-1, was purified from the halo-alkalophilic Bacillus sp. 17N-1, and found active in media containing dithiothreitol and EDTAK(2). This enzyme maintained significant activity from pH 6.

Taxonomic identification, phenanthrene uptake activity, and membrane lipid alterations of the PAH degrading Arthrobacter sp. strain Sphe3.

This report describes phenanthrene uptake as well as the effect of phenanthrene on the membrane phospholipid and fatty acid composition in a newly isolated bacterial strain, Sphe3, that we taxonomically identified as Arthrobacter sp. Strain Sphe3 is able to utilize phenanthrene as a carbon source at high rates and appears to internalize phenanthrene with two mechanisms: a passive diffusion when cells are grown on glucose, and an inducible active transport system when cells are grown on phenanthrene as a sole carbon source. Active transport followed Michaelis-Menten kinetics, and it was amenable to inhibition by 2,4-dinitrophenol and sodium azide.

Design and synthesis of cationic Aib-containing antimicrobial peptides: conformational and biological studies.

Development of antimicrobial peptides has attracted considerable attention in recent years due to the excessive use of antibiotics, which has led to multiresistant bacteria. Cationic amphiphilic Aib-containing peptide models Ac-(Aib-Arg-Aib-Leu)(n)-NH2, n = 1-4, and sequential cationic polypeptides (Arg-X-Gly)(n), X = Ala, Val, Leu, were prepared and studied for their antimicrobial and hemolytic activity, as well as for their proteolytic stability. Ac-(Aib-Arg-Aib-Leu)(n)-NH2, n = 2, 3 and the polypeptide (Arg-Leu-Gly)(n) exhibited significant antimicrobial activity, and they were nontoxic at their MIC values and resistant, in particular the Aib-peptide models, to enzymatic degradation.

Contribution of chemical changes in membrane lipids to the osmoadaptation of the halophilic bacterium Chromohalobacter salexigens.

The long-term response of the broad-salt growing halophile Chromohalobacter salexigens DSM 3043T to salt stress has been investigated with respect to adaptive changes in membrane lipid composition. This study included the wild-type and three salt-sensitive, ectoine-deficient strains: CHR62 (ectA::Tn1732, unable to grow above 0.75 M NaCl), CHR63 (ectC::Tn1732, unable to grow above 1.

Transcriptional analysis of a gene cluster involved in glucose tolerance in Zymomonas mobilis: evidence for an osmoregulated promoter.

Exponentially growing cells of Zymomonas mobilis normally exhibit a lag period of up to 3 h when they are transferred from a liquid medium containing 2% glucose to a liquid medium containing 10% glucose. A mutant of Z. mobilis (CU1) exhibited a lag period of more than 20 h when it was grown under the same conditions, whereas it failed to grow on a solid medium containing 10% glucose.

Gene transfer and expression of recombinant proteins in moderately halophilic bacteria.

Moderately halophilic bacteria (MHB) of the genera Halomonas and Chromohalobacter have been used as hosts for the expression of heterologous proteins of biotechnological interest, thus expanding their potential to be used as cell factories for various applications. This chapter deals with the methodology for the construction of recombinant plasmids, their transfer to a number of MHB, and the assaying of the corresponding heterologous proteins activity. The transferred genes include (1) inaZ, encoding the ice nucleation protein of the plant pathogen Pseudomonas syringae, (2) gfp, encoding a green fluorescent protein from the marine bioluminescent jellyfish Aequorea victoria, and (3) the alpha-amylase gene from the hyperthermophilic archeon Pyrococcus woesei.

Isolation and characterization of novel bacteria degrading polycyclic aromatic hydrocarbons from polluted Greek soils.

Three bacterial strains, designated as Wphe1, Sphe1, and Ophe1, were isolated from Greek soils contaminated with polycyclic aromatic hydrocarbon (PAH)-containing waste from the wood processing, steel, and oil refinery industries. Wphe1, Sphe1, and Ophe1 were characterized and identified as species of Pseudomonas, Microbacterium, and Paracoccus, respectively, based on Gram staining, biochemical tests, phospholipid analysis, FAME analysis, G+C content and 16S rRNA gene sequence analysis. The results of gas chromatography showed that strain Wphe1 degraded naphthalene, phenanthrene, and m-cresol over a wide temperature range; strain Sphe1 was a degrader of phenanthrene and n-alkanes; most interestingly, strain Ophe1 degraded anthracene, phenanthrene, fluorene, fluoranthene, chrysene, and pyrene, as well as cresol compounds and n-alkanes as sole carbon source.

A classification scheme for mobilization regions of bacterial plasmids.

Transmissible plasmids can be classified according to their mobilization ability, as being conjugative (self-transmissible) or mobilizable (transmissible only in the presence of additional conjugative functions). Naturally occurring mobilizable plasmids carry the genetic information necessary for relaxosome formation and processing, but lack the functions required for mating pair formation. Mobilizable plasmids have a tremendous impact in horizontal gene transfer in nature, including the spread of antibiotic resistance.

Genetic and biochemical characterization of MbeA, the relaxase involved in plasmid ColE1 conjugative mobilization.

MbeA is a 60 kDa protein encoded by plasmid ColE1. It plays a key role in conjugative mobilization. MbeA*, a slightly truncated version of MbeA, was purified for in vitro analysis.