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A Geis

Publications and source records attributed to A Geis.

16 recordsLinked to original sources
PubMed2004

Molecular identification and differentiation of Staphylococcus species and strains of cheese origin.

Amplified Ribosomal-DNA Restriction Analysis (ARDRA) was used to differentiate among 12 species and 4 subspecies of the genus Staphylococcus. With a universal primer pair a 2.4 kbp PCR-product was amplified, including the 16S rDNA, the 16S-23S rDNA interspacer region, and about 500 bp of the 23S rDNA. Species-specific restriction patterns were found using the restriction enzymes HindIII and XmnI separately. Cheese related staphylococci were clearly differentiated. ARDRA results were in good agreement with results of partial sequencing of the 16S rDNA. ARDRA could fully replace the biochemical identification with ID32 Staph (BioMerieux) which was less reliable when staphylococci of cheese origin were analysed. Genomic restriction digests of cheese-related S. equorum strains by SmaI and SacI gave unique strain-specific restriction patterns which can be used to identify starter staphylococci in a complex microbial environment such as the surface of Red-Smear cheeses.

Cheese↗
PubMed2003

Identification and differentiation of species and strains of Arthrobacter and Microbacterium barkeri isolated from smear cheeses with Amplified Ribosmal DNA Restriction Analysis (ARDRA) and pulsed field gel electrophoresis (PFGE).

ARDRA (Amplified Ribosomal-DNA Restriction Analysis) was used to differentiate among species and genera of Arthrobacter and Microbacteria. Species-specific restriction patterns of PCR-products were obtained with NciI for Arthrobacter citreus (DSM 20133T), A. sulfureus (DSM 20167T), A. globiformis (DSM 20124T) and A. nicotianae strains (DSM 20123T, MGE 10D, CA13, CA14, isolate 95293, 95294, and 95299), A. rhombi CCUG 38813T, and CCUG 38812, and Microbacterium barkeri strains (DSM 30123T, MGE 10D, CA12 and CA15, isolate 95292, and isolate 95207). All yellow pigmented coryneforme bacteria isolated from the smear of surface ripened cheeses were identified as either A. nicotianae or M. barkeri strains. Using pulsed field gel electrophoresis (PFGE) strain specific restriction pattern for all Arthrobacter species and Microbacteria tested were obtained with restriction enzymes AscI and SpeI.

Actinomycetales↗
PubMed1998

Bacillus subtilis develops competence for uptake of plasmid DNA when growing in milk products.

Transformation with plasmid DNA of naturally competent cells of Bacillus subtilis 168 in milk products was studied. Plasmid pMG36enpr, a broad host-range lactococcal vector carrying an erythromycin resistance and the B. subtilis npr gene encoding neutral protease, was taken up by B. subtilis cells grown in UHT chocolate milk. Under these conditions competence was optimal during transition from exponential to stationary growth phase, resulting in 9 x 10(1) transformants per 0.01 microgram DNA. No manipulation of the cells was necessary for competence to develop. When cells were pregrown in synthetic medium, higher transformation rates were obtained in assays, where the subsequent transformation experiments were either done in chocolate milk diluted 1:1 (v/v) with synthetic growth medium (up to 8 x 10(2) transformants) or in undiluted chocolate milk (1 x 10(2) transformants). The number of transformants was reduced to 4 x 10 (1), when diluted milk or flavored milks were used. No transformants were obtained in diluted yoghurt. Controls, in which both the preculturing and the transformation assays were done in synthetic medium, gave the maximum number of transformants (4 x 10(3) transformants per 0.01 microgram DNA).

Bacillus subtilis↗
PubMed1992

Sequencing and characterization of pST1, a cryptic plasmid from Streptococcus thermophilus.

Eighty-six strains of S. thermophilus were examined for their plasmid content. Thirteen strains were found to contain one or two plasmids ranging in size from 2.1 to 7.4 kb. DNA-DNA hybridization analysis revealed the presence of five distinct groups of DNA homology. The complete nucleotide sequence of plasmid pST1 (Accession number X65856), which belongs to the major homology group, was determined. It has a molecular size of 2093 bp, a GC content of 35% and contains one major open reading frame of 945 bp (ORF A). The predicted protein, designated Rep A, showed sequence homology with replication proteins from a group of plasmids which are known to replicate via single-stranded DNA intermediates (ssDNA plasmids).

Amino Acid Sequence↗
PubMed1991

Identification, cloning and sequencing of the replication region of Lactococcus lactis ssp. lactis biovar. diacetylactis Bu2 citrate plasmid pSL2.

The replication region of the 7.8 kilobase (kb) citrate plasmid pSL2 from Lactococcus lactis ssp. lactis biovar. diacetylactis Bu2 was identified. Deletion derivatives of pSL2 were introduced into plasmid-free strain Bu2-60 and tested for their ability to replicate autonomously. The region necessary for replication was identified by comparison of the pSL2 derivatives, cloned and sequenced. No homologies were detected by comparing the putative Rep protein of pSL2 with replicons of other plasmids of Gram-positive bacteria. A part of an IS-element flanking the replication region was found.

Amino Acid Sequence↗
PubMed1991

Distribution of the IS elements ISS1 and IS904 in lactococci.

A broad distribution of the lactococcal IS elements ISS1 [1] and IS904 [2] in several lactococcal plasmids and chromosomal DNA was observed. Hybridization of the ISS1 and IS904 oligonucleotide gene probes with DNA of lactococcal phages showed that none of these tested bacteriophages contained one of the IS elements. On the transductionally shortened lactose plasmid pTD1 an insertion sequence homologous to ISS1 was identified closely downstream to the P-beta-galactosidase gene. Sequence analysis of ISS1/pTD1 showed 82% homology in the deduced amino acid sequence to the putative transposase of ISS1, ISS1W, ISS1N, and IS946.

Amino Acid Sequence↗
PubMed1991

Bacteriophage receptors of Lactococcus lactis subsp. 'diacetylactis' F7/2 and Lactococcus lactis subsp. cremoris Wg2-1.

Bacteriophage P008 revealed irreversible and uniform adsorption to cell walls of L. lactis subsp. 'diacetylactis' F7/2, whereas phage P127 adsorbed reversibly to a limited number of receptor sites on cell walls of L. lactis subsp. cremoris Wg2-1. Neither extraction of lipids, cell wall- and membrane-teichoic acids nor enzymatic degradation of proteins altered the binding efficiencies of both cell wall fractions. However, phage binding was inhibited, when cell walls were subjected to lysozyme, metaperiodate, or acid treatments. This reflects that a carbohydrate component embedded in the peptidoglycan matrix is part of the phage receptors of strains F7/2 and Wg2-1.

Adsorption↗
PubMed1989

Cloning of two bacteriocin genes from a lactococcal bacteriocin plasmid.

Lactococcus lactis subsp. cremoris 9B4 plasmid p9B4-6 (60 kilobases [kb]), which specifies bacteriocin production and immunity, was analyzed with restriction endonucleases, and fragments of this plasmid were cloned into shuttle vectors based on the broad-host-range plasmid pWVO1. Two regions on p9B4-6 were identified which specify inhibitory activity on L. lactis indicator strains: one that could be confined to a 1.8-kb ScaI-ClaI fragment with low antagonistic activity and a 15-kb XbaI-SalI fragment specifying high antagonistic activity. The inhibitory substances produced by these two clones were sensitive to proteolysis. A 4-kb HindIII fragment derived from the 15-kb fragment strongly hybridized with the 1.8-kb fragment. The antagonistic activity specified by the 4-kb fragment was somewhat reduced as compared with that of the 15-kb fragment. A 1.3-kb ScaI-HindIII subfragment of the 4-kb fragment contained both the immunity and bacteriocin genes. Inhibition studies showed that the two bacteriocins had different specificities.

Bacteriocins↗
PubMed1988

Plasmid-encoded functions of ropy lactic acid streptococcal strains from Scandinavian fermented milk.

Ropy Streptococcus (Lactococcus) cremoris strains isolated from a ropy Swedish sour milk ("longfil") and a ropy Finnish milk product ("Viili") were screened for their plasmid-encoded functions. Curing experiments strongly indicated that the ropy phenotype was linked to a 17-Md plasmid in the Swedish strains and to a 30 Md plasmid in the Finnish strains. Comparative restriction endonuclease analysis and DNA/DNA-hybridization studies revelated that plasmids from both strain families shared homologous DNA regions. Though be Swedish ropy strains harbored a conjugative 45-Md lactose plasmid, no cotransfer of the 17 Md plasmid occurred.

Animals↗
PubMed1984

Conjugal transfer and characterization of bacteriocin plasmids in group N (lactic acid) streptococci.

Thirteen bacteriocin-producing strains of group N (lactic acid) streptococci were screened for their potential to transfer this property by conjugation to Streptococcus lactis subsp. diacetylactis Bu2-60. Bacteriocin production in three strains was plasmid encoded as shown by conjugal transfer and by analysis of cured, bacteriocin-negative derivatives of the donor strains and the transconjugants. With Streptococcus cremoris strains 9B4 and 4G6 and S. lactis subsp. diacetylactis 6F7 as donors, bacteriocin-producing transconjugants were isolated with frequencies ranging from ca. 2 X 10(-2) to 2 X 10(-1) per recipient cell. Bacteriocin-producing transconjugants had acquired a 39.6-megadalton plasmid from the donor strains 9B4 and 4G6, and a 75-megadalton plasmid from the donor strain 6F7. As shown by restriction endonuclease analysis, the plasmids from strains 9B4 and 4G6 were almost identical. The plasmid from strain 6F7 yielded some additional fragments not present in the two other plasmids. In hybridization experiments any of the three plasmids strongly hybridized with each other and with some other bacteriocin but nontransmissible plasmids from other S. cremoris strains. Homology was also detected to a variety of cryptic plasmids in lactic acid streptococci.

Bacteriocins↗
PubMed1983

Potential of lactic streptococci to produce bacteriocin.

A survey was made on the bacteriocin-producing potential of lactic streptococci. Bacteriocin-like activities were isolated and partially purified from about 5% of the 280 strains investigated. The frequency of production varied from about 1% in Streptococcus lactis subsp. diacetylactis to 9 and 7.5% in S. lactis and Streptococcus cremoris, respectively. Eight strains of S. cremoris produced bacteriocins which, on the basis of heat stability at different pH values and inhibitory spectrum, could be divided into four types. From 54 S. lactis strains, 5 strains produced inhibitory substances, namely, three nisin-like antibiotics and two different bacteriocins. Only 1 of 93 S. lactis subsp. diacetylactis strains produced a bacteriocin which was very similar to bacteriocins of type I in S. cremoris. All of the bacteriocins that were partially purified by ammonium sulfate precipitation showed very limited inhibitory spectra. Most of the lactic streptococci and a few members of the genera Clostridium, Leuconostoc, and Pediococcus were inhibited. None of the bacteriocins acted on gram-negative bacteria. The bacteriocinogenic strains were also characterized on the basis of plasmid content. All strains possessed between one and nine plasmids ranging from 1 to 50 megadaltons.

Journal Article↗
PubMed1978

Phospho-N-acetylmuramoyl-pentapeptide-transferase of Escherichia coli K12. Properties of the membrane-bound and the extracted and partially purified enzyme.

Phospho-N-acetylmuramoyl-pentapeptide-transferase (UDP-N-acetyl-muramoyl-L-alanyl-D-gamma-glutamyl-L-lysyl-D-alanyl-D-alanine:undecaprenoid-alcohol-phosphate-phospho-N-acetylmuramoyl-pentapeptide-transferase, EC 2.7.8.13) was solubilized by repeated freezing and thawing of crude envelopes of Escherichia coli K12. The solubilized enzyme was partially purified by gel filtration and ion-exchange chromatography. This preparation contained small amounts of phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol but no endogenous lipid substrate, C55-isoprenyl phosphate, could be detected. Some catalytic properties (exchange reaction) of the solubilized enzyme were compared to those of membrane-bound transferase. The transfer activity of the partially purified transferase was restored by the addition of an aqueous lipid dispersion. All the transferase activity was found to become incorporated into the liposomes. Preincubation of the transferase preparation with phospholipase A2 or D strongly reduce both exchange and transfer activity. This suggests that phospholipids sensitive to phospholipases are necessary for the enzymatic reaction. Different effects of some neutral detergents on the exchange activity were reported.

Cell Membrane↗