Control of the growth of Alicyclobacillus acidoterrestris in industrialized orange juice using rosemary essential oil and nisin

The use of rosemary essential oil (RO) and its combination with nisin (RO+N) in preventing the multiplication of Alicyclobacillus acidoterrestris in orange juice was evaluated. The minimum inhibitory and bactericidal concentrations (MIC and MBC) for RO were both 125 μg ml⁻¹ while RO+N displayed a synergistic effect. The use of RO and RO+N at concentrations of 1, 4 and 8× MIC in orange juice for 96 h was evaluated in terms of their sporicidal effectiveness. With regard to the action against A. acidoterrestris spores, RO at 8× MIC was sporostatic, whereas RO+N at 1× MIC was sporicidal. Morphological changes in the structure of the micro-organism after treatment were also observed by microscopy. Furthermore, flow cytometric analysis showed that most cells were damaged or killed after treatment. In general, the antioxidant activity after addition of RO+N decreased with time. The results demonstrate that using the combination of RO and nisin can prevent the A. acidoterrestris growth in orange juice.     

R plasmids in environmental Vibrio cholerae non-O1 strains

The occurrence of drug resistance and its plasmid-mediated transferability was investigated in 140 environmental strains of Vibrio cholerae non-O1 and 6 strains of Vibrio cholerae, both O1 and non-O1, of clinical origin. Of the 146 strains tested, 93% were resistant to at least one drug and 74% were resistant to two or more antibiotics. The O1 strains were susceptible to all antibiotics used. A total of 26 of 28 selected resistant wild strains carried R plasmids that were transferable by intraspecific and intergeneric matings. The most common transmissible R factor determined resistance to ampicillin, amoxicillin, and sulfanilamide (30%), followed by resistance to ampicillin and amoxicillin (13%) and resistance to ampicillin, amoxicillin, phosphomycin, and sulfanilamide (9%). Comparison of the three methods of plasmid analysis showed that the method of Birnboim and Doly (Nucleic Acids Res. 7:1513-1523, 1979) without EDTA and lysozyme was optimal for isolation of both large and small plasmids in environmental V. cholerae strains. Most strains harbored more than one plasmid, and the molecular sizes ranged from 1.1 to 74.8 megadaltons. The plasmids of high molecular size (around 74 megadaltons) were responsible for the resistance pattern transferred and were maintained with high stability in the hosts.     

Early-blocked sporulation mutations alter expression of enzymes under carbon control in Bacillus subtilis

Summary The physiological roles of the gene subset defined by early-blocked sporulation mutations (spo0) and their second-site suppressor alleles (rvtA11 and crsA47) remain cryptic for both vegetative and sporulating Bacillus subtilis cells. To test the hypothesis that spo0 gene products affect global regulation, we assayed the levels of carbon- and nitrogen-sensitive enzymes in wild-type and spo0 strains grown in a defined minimal medium containing various carbon and nitrogen sources. All the spo0 mutations (except spo0J) affected both histidase and arabinose isomerase levels in an unexpected way: levels of both carbon-sensitive enzymes were two- to six-fold higher in spo0 strains compared to wild type, when cells were grown on the derepressing carbon sources arabinose or maltose. There was no difference in enzyme levels with glucose-grown cells, nor was there a significant difference in levels of the carbonindependent enzymes glutamine synthetase and glucose-6-phosphate dehydrogenase. This effect was not due to a slower growth rate for the spo0 mutants on the poor carbon and nitrogen sources used. The levels of carbon-sensitive enzymes were not simply correlated with sporulation ability in genetically suppressed spo0 mutants, but the rvtA and crsA suppressors each had such marked effects on wild-type growth and enzyme levels that these results were difficult to interpret. We conclude that directly or indirectly the spo0 mutations, although blocking the sporulation process, increase levels of carbon-sensitive enzymes, possibly at the level of gene expression.     

An insertion within the factor IX gene: hemophilia BEl Salvador.

A patient with moderate to severe hemophilia B has been found to have a large insertion within his factor IX gene. The site of insertion is located in a DNA segment of approximately 0.8 kb between exon IV and an EcoRI site within intron D. The size of the DNA insertion is approximately 6 kb, and it contains at least two TaqI sites, two EcoRI sites, and one HindIII site. The insert probably originates from outside the FIX gene and does not represent an internal duplication. We propose that this abnormal FIX gene be called FIX El Salvador in recognition of the birthplace of the patient.     

New common nomenclature for glycoprotein genes of varicella-zoster virus and their glycosylated products.

The accumulation of recent data concerning the reactivity of monoclonal antibodies with particular varicella-zoster virus (VZV) glycoproteins and the mapping of several of their respective genes on the VZV genome has led to a unified nomenclature for the glycoprotein genes of VZV and their mature glycosylated products. Homologs to herpes simplex virus glycoprotein genes are noted.     

Surface and virulence properties of environmental Vibrio cholerae non-O1 from Albufera Lake (Valencia, Spain).

A total of 140 environmental Vibrio cholerae non-O1 isolates, together with several culture collection strains from both environmental and clinical sources, were studied in relation to hemagglutination, surface hydrophobicity, and the enzymatic, hemolytic, cytotoxic, and enterotoxic activities of their extracellular products. A total of 78 and 62% of the strains produced hemagglutinins and exohemagglutinins, respectively. Four different hemagglutinating and two exohemagglutinating activities were found by using eight sugars in the inhibition assays. Cell-bound mannose-sensitive hemagglutination was detected mainly in chicken blood, whereas fucose-sensitive hemagglutination was recorded only in human blood. Cell-bound hemagglutinin resistant to all sugars tested was the only one related to surface hydrophobicity. The surface properties varied along the growth curves. The non-O1 strains displayed strong enzymatic and hemolytic activities, except for esculin hydrolysis. Of 26 non-O1 isolates selected for cytotoxin and enterotoxin production, 23 showed a wide spectrum of cytotoxic effects on cell lines of poikilothermic and homoiothermic species, but they were weakly enterotoxigenic in the infant mouse test. All extracellular products of cytotoxic strains were proteolytic, lipolytic, and hemolytic, and a high percentage produced hemagglutination of chicken blood. The cytotoxic factors in the non-O1 strains analyzed were not R plasmid mediated.     

Iron-binding compounds and related outer membrane proteins in Vibrio cholerae non-O1 strains from aquatic environments

A total of 156 strains of Vibrio cholerae non-O1 from aquatic origins were examined for the presence of iron uptake mechanisms and compared with O1 strains and other Vibrio species. All non-O1 strains were able to grow in iron-limiting conditions, with MICs of ethylenediaminedi (O-hydroxyphenylacetic acid) ranging from 20 microM to 2 mM. The production of siderophores was demonstrated by growth in chrome azurol S agar and cross-feeding assays. All strains produced phenolate-type compounds, as assessed by the chemical tests and by bioassays with Salmonella typhimurium enb-7. Some of the strains also promoted the growth of S. typhimurium enb-1 (which can use only enterobactin as a siderophore) as well as some strains of Vibrio anguillarum deficient in the anguibactin-mediated system. The chromatographic analyses and absorption spectra of siderophores extracted from culture supernatants suggest that vibriobactin may be produced by the strains examined. Interestingly, some strains also produced hydroxamate-type compounds, as determined by chemical tests, and were able to promote the growth of an aerobactin-deficient strain of Escherichia coli. These results were confirmed by the absorption spectra and chromatographic analyses of the culture extracts. The synthesis of iron-regulated outer membrane proteins in representative strains was also examined. The molecular sizes of the main induced proteins ranged from 70 to 78 kilodaltons. These results indicate that several iron uptake mechanisms which could be involved in environmental survival and pathogenicity are present in environmental V. cholerae non-O1 strains.     

Siderophore-mediated iron acquisition mechanisms in Vibrio vulnificus biotype 2.

Vibrio vulnificus biotype 2 is a primary pathogen for eels and, as has recently been suggested, an opportunistic pathogen for humans. In this study we have investigated the ability of V. vulnificus biotype 2 to obtain iron by siderophore-mediated mechanisms and evaluated the importance of free iron in vibriosis. The virulence degree for eels was dependent on iron availability from host fluids, as was revealed by a reduction in the 50% lethal dose for iron-overloaded eels. This biotype produced both phenolate- and hydroxamate-type siderophores of an unknown nature and two new outer membrane proteins of around 84 and 72 kDa in response to iron starvation. No alterations in lipopolysaccharide patterns were detected in response to iron stress. Finally, our data suggest that V. vulnificus biotype 2 uses the hydroxamate-type siderophore for removal of iron from transferrin rather than relying on a receptor for this iron-binding protein.