Random Amplified Polymorphic DNA-polymerase Chain Reaction Research Articles

Genetic variability of Pantaneiro horse using RAPD-PCR markers

Blood samples were collected from Pantaneiro Horses in five regions of Mato Grosso do Sul and Mato Grosso States. Arabian, Mangalarga Marchador and Thoroughbred were also included to estimate genetic distances and the existing variability among and within these breeds by RAPD-PCR (Random Amplified Polymorphic DNA - Polymerase Chain Reaction) molecular markers. From 146 primers, 13 were chosen for amplification and 44 polymorphic bands were generated. The analysis of molecular variance (AMOVA) indicated that the greatest portion of detected variability was due to differences between individuals within populations (75.47%). Analysis of the genetic variability between pairs of populations presented higher estimates for the five Pantaneiro populations with the Arabian breed, while lowest estimates were presented by pairs formed among the Pantaneiro populations with the Mangalarga Marchador. Highest genic diversity was shown by the Pantaneiro (0.3396), which also showed highest genetic distance with the Arabian and lowest with Mangalarga Marchador breed. UPGMA dendrogram showed distinct differences between naturalized (Pantaneiro and Mangalarga Marchador) and exotic (Arabian and Thoroughbred) breeds. In the dendrogram generated by UPGMA method, the similarity matrix generated by the Jaccard coefficient showed distinction between the naturalised breeds, Pantaneiro and Mangalarga Marchador, and the exotic breeds, Árab and English Thoroughbred. Results suggest that the Pantaneiro presents a higher genetic variability than the other studied breeds and has a close relationship with the Mangalarga Marchador.

Molecular Typing of Aspergillus terreus Isolates Collected in Houston, Texas, and Innsbruck, Austria: Evidence of Great Genetic Diversity

Aspergillus terreus isolates collected from patients at The M. D. Anderson Cancer Center in Houston, TX, and at The University Hospital of Innsbruck, Austria, were analyzed using random amplification of polymorphic DNA-PCR with three different primers. No strain similarity in either institution was detected, indicating great genetic diversity of A. terreus.

Insertion sequence elements as mediators of strain diversity in Lactobacillus helveticus

Insertion sequence (IS) elements were found to be associated with the truncation of predicted cellobiose transport, acetaldehyde dehydrogenase and diacetyl reductase genes in the genome of Lactobacillus helveticus DPC 4571. The conservation of the IS elements in these different genomic locations among L. helveticus cheese isolates was determined by amplification with gene-specific and IS element-specific primers. The presence of two of the IS elements was found to follow a genotypic profile of the strains generated by randomly amplified polymorphic DNA (RAPD)–PCR and strains that clustered by RAPD–PCR tended to have the IS element in the same position. However, the IS element that interrupted the cellobiose transport gene was found to be common to all strains tested. This conserved genotype suggests the insertion event occurred early in the evolution of L. helveticus as a separate species.

Investigation of mealybug (hemiptera: Coccoidea: Pseudococcidae) species from Turkey by RAPD

Molecular markers are commonly used for determining the relationship between insect species. In this study, we investigated the relationship of six mealybug species,Planococcus citri (Risso),Planococcus ficus (Signoret),Planococcus vovae (Nasonov),Pseudococcus longispinus (Targioni Tozzetti),Pseudococcus viburni (Signoret) andPhenacoccus aceris (Signoret), sampled from Turkey, using randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). Of the 50 RAPD primers tested, 18 identified a total of 256 fragments of which all were polymorphic. Sufficient discrimination betweenP. citri andP. ficus was provided by several RAPD primers. The genetic distance values calculated for each pair-wise comparison ranged from 0.156 to 0.504. Cluster analyses of RAPD data clearly separated the species into two groups.

Serologic and molecular characterization of Pseudomonas aeruginosa Jordanian clinical isolates compared with the strains of International Antigenic Typing Scheme

One hundred clinical isolates of Pseudomonas aeruginosa were serologically classified into 7 Jordanian serotypes (labeled JO1–JO7) Odeh, 2002, M.Sc. thesis, University of Jordan). Using the slide agglutination test, 4 of them (JO4, JO5, JO6, and JO7) were serologically matched with the International Antigenic Typing Scheme (IATS) strains (IATS 20, IATS 10, IATS 6, and IATS 11). One serotype (JO1) showed a weak cross-reaction with IATS 1. The remaining 2 local serotypes (JO2 and JO3) did not react with any of the 20 IATS strains. Serologic analysis data showed to a certain extent correlations with molecular data using genetic clustering and similarity indices generated by random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). Each of the 4 identified local serotypes formed a cluster with its serologically matched IATS strain with relatively high average similarity indices, whereas lower average similarity index was observed between IATS 1 and JO1, in consistence with the weak serologic reaction using the slide agglutination test. On the other hand, the 2 nontypeable serotypes (JO2 and JO3) formed 2 separate clusters that could not be matched to any of the IATS strain. Phenotypic and genotypic analyses suggest that JO2 and JO3, and possibly JO1, can be new serotypes of P. aeruginosa. RAPD-PCR was also used to study the relative relatedness among the 20 IATS strains. The IATS strains formed 2 main clusters. Half of the IATS strains formed one main cluster that included IATS 11–20. The remaining IATS strains (8 strains) formed the second main cluster, with the exception of IATS 4 and 9, where each formed a separate cluster.

Sensitivity of two techniques to detect Escherichia coli O157 in naturally infected bovine fecal samples

The aim of this study was to investigate the sensitivity and reliability of two techniques commonly used for the isolation of Escherichia coli O157: (i) buffered peptone water (BPW) containing vancomycin, cefsulodin and cefixime followed by immunomagnetic separation (IMS-VCC) and (ii) modified E. coli (EC) broth supplemented with novobiocin (m ECn), both followed by culturing on cefixime tellurite sorbitol McConkey (ctSMAC) agar plates. Over a 2-year period, 24 feedlots located over a large geographical area (∼600×450 km) were screened for the presence of E. coli O157. A total of 194 E. coli O157 isolates were identified; 151 (77.4%) using IMS-VCC and 108 (55.4%) using m ECn. The recovery rates of IMS-VCC varied from 100% to 47%, whereas for m ECn ranged from 100% to 16%. All isolates were grouped, using randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR), into 3 major clusters that comprised 39 different subtypes, providing evidence of considerable genetic heterogeneity. The results from this study revealed false negatives in IMS-VCC technique, most probably due to the high genetic diversity of environmental E. coli O157 isolates and antibiotic sensitivity. Using only IMS-VCC as a method for detection may result in significant underestimation of the pathogen. Performing two different enrichment steps in parallel can lead to markedly improved recovery rates of E. coli O157 isolates from naturally infected samples.

Postcopulatory Sexual Selection Reduces Genetic Diversity in Experimental Populations of Caenorhabditis elegans

Postcopulatory sexual selection affects the evolution of numerous features ranging from mating behavior to seminal fluid toxicity to the size of gametes. In an earlier study of the effect of sperm competition risk on sperm size evolution, experimental populations of the nematode Caenorhabditis elegans were maintained either by outcrossing (sperm competition present) or by selfing (no sperm competition), and after 60 generations, significantly larger sperm had evolved in the outcrossing populations. To determine the effects of this selection on population genetic variation, we assessed genetic diversity in a large number of loci using random amplification of polymorphic DNA-PCR. Nearly 80% of the alleles present in parental strain populations persisted in the 6 experimental populations after the 60 generations and, despite a 2.2-fold difference in expected heterozygosity, the resulting levels of genetic variation were equivalent between the outcrossing and selfing experimental populations. By inference, we conclude that genetic hitchhiking due to sexual selection in the experimental populations dramatically reduced genetic diversity. We use the levels of variation in the selfing populations as a control for the effects of drift, and estimate the strength of sexual selection to be strong in obligatorily outcrossing populations. Although sequential hermaphrodites like C. elegans probably experience little sexual selection in nature, these data suggest that sexual selection can profoundly affect diversity in outcrossing taxa.

Selección e implantación de cepas de levadura del género Saccharomyces en la producción de vinos de la Denominación de Origen (DO) Chacolí de Vizcaya/Bizkaiko Txakolina

The white wine Chacolía de Vizcaya/Bizkaiko Txakolina is characteristic from The Basque Country region and regulated under Appellation Contrôlée standards (BOPV 14/6/94). The objective of this study was the identification and selection of autochthonous yeast strains, to improve the conditions used to maintain the typical characteristics of this region wines. Yeasts identified as Saccharomyces bayanus isolated around these fields from 1996 to 1998, were subjected to a selective procedure based on enological characteristics and fermentative behaviour. Three of the selected strains were used to inoculate, at winery scale, two grape juice varieties accepted by the Appellation Contrôlée (Hondarrabi Zuri and Folle Blanche). The inoculated strains on the respective vinifications was followed by restriction fragment length polymorphism of mitochondrial DNA (REAmt) method with AluI enzyme, due to their specificity, short outcome, and technological simplicity compared with other molecular typing methods such as: chromosomal karyotyping analyzed by pulsed field gel electrophoresis, Random Amplified Polymorphic DNA-PCR (RAPD-PCR) and restriction fragment length polymorphism using the infrequently cutting enzyme SfiI (REA infrequent). This study demonstrated that strains with different phenotypic traits could show indistinguishable restriction patterns with REAmt, but could be discriminated using other typing methods such as RAPD-PCR, which although showing low reproducibility could be used as complementary to REAmt. Our results demonstrate that in spite of using autochthonous selected strains, the inoculation of musts with a particular strain do not guarantee its predominance and driving fermentation features. Of all yeast strains studied, strain no. 2 showed the best results in sensory testing and at the implantation process. Therefore, it could be used with commercial purposes for the production of Chacolí de Vizcaya/Bizkaiko Txakolina, especially when using musts from Folle Blanche.

Genetic Analysis of Haimen Chicken Populations Using Decamer Random Markers

Through a screening and selection approach method, decamer random markers were used in a technique called random amplified polymorphic DNA (RAPD) assay with 252 genomic DNAs isolated from four major Haimen chicken populations: Rugao (62), Jiangchun (62), Wan-Nan (63) and Cshiqishi (65). A total of 3-score decamer random primers (S241-S260, S1081-S1100 and S1341-S1360) were employed in the preliminary RAPD-polymerase chain reaction (RAPD-PCR) assay with 50 random template DNA samples from all the populations. Four (6.67%) of the primers that produced obvious polymorphic patterns, interpretable and reproducible bands were selected and used with both the individual DNAs from each population and with pooled DNA samples of the four populations in subsequent analyses. The selected primers produced a total of 131 fragments with molecular size ranging from 835 to 4,972 base pairs (bp) when used with the individual DNAs; 105 (80.15%) of these fragments were polymorphic. With the pooled DNAs, 47 stable and characteristic bands with molecular size ranging from 840 to 4,983 bp, of which 23 (48.94%) polymorphic, were also generated. The band-sharing coefficient (BSC) calculated for the individuals in the population and among populations of bulked samples was between 0.8247 (Rugao) and 0.9500 (Cshiqishi); for pairwise populations, it was between 0.7273 (Rugao vs. Wan-Nan) and 0.9367 (Jiangchun vs. Cshiqishi) chicken populations. Using the BSC for individual and pairwise populations, the Nei's standard genetic distances between the chicken populations were determined and ranged from 0.0043 (Jiangchun vs. Cshiqishi) to 0.1375 (Rugao vs. Cshiqishi). The reconstructed dendrogram linked the Jiangchun and Cshiqishi chickens as closely related populations, followed by Wan-Nan, while the Rugao was the most genetically distant among the populations.

Genetic Variability of Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) Populations from Latin America Is Associated with Variations in Susceptibility to Bacillus thuringiensis Cry Toxins

Bacillus thuringiensis strains isolated from Latin American soil samples that showed toxicity against three Spodoptera frugiperda populations from different geographical areas (Mexico, Colombia, and Brazil) were characterized on the basis of their insecticidal activity, crystal morphology, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of parasporal crystals, plasmid profiles, and cry gene content. We found that the different S. frugiperda populations display different susceptibilities to the selected B. thuringiensis strains and also to pure preparations of Cry1B, Cry1C, and Cry1D toxins. Binding assays performed with pure toxin demonstrated that the differences in the toxin binding capacities of these insect populations correlated with the observed differences in susceptibility to the three Cry toxins analyzed. Finally, the genetic variability of the three insect populations was analyzed by random amplification of polymorphic DNA-PCR, which showed significant genetic diversity among the three S. frugiperda populations analyzed. The data presented here show that the genetic variability of S. frugiperda populations should be carefully considered in the development of insect pest control strategies, including the deployment of genetically modified maize in different geographical regions.

Long-term storage and safe retrieval of DNA from microorganisms for molecular analysis using FTA matrix cards

We assessed the potential use of Whatman FTA® paper as a device for archiving and long-term storage of bacterial cell suspensions of over 400 bacterial strains representing 61 genera, the molecular applications of immobilised DNA on FTA paper, and tested its microbial inactivation properties. The FTA paper extracted bacterial DNA is of sufficiently high quality to successfully carryout the molecular detection of several key genes including 16S rRNA, esp ( Enterococcus surface protein), Bft ( Bacteroides fragilis enterotoxin) and por (porin protein) by PCR and for DNA fingerprinting by random amplified polymorphic DNA-PCR (RAPD-PCR). To test the long-term stability of the FTA immobilised DNA, 100 of the 400 archived bacterial samples were randomly selected following 3 years of storage at ambient temperature and PCR amplification was used to monitor its success. All of the 100 samples were successfully amplified using the 16S rDNA gene as a target and confirmed by DNA sequencing. Furthermore, the DNA was eluted into solution from the FTA cards using a new alkaline elution procedure for evaluation by real-time PCR-based assays. The viability of cells retained on the FTA cards varied among broad groups of bacteria. For the more fragile gram-negative species, no viable cells were retained even at high cell densities of between 10 7 and 10 8 colony forming units (cfu) ml − 1 , and for the most robust species such as spore-formers and acid-fast bacteria, complete inactivation was achieved at cell densities ranging between 10 1 and 10 4 cfu ml − 1 . The inactivation of bacterial cells on FTA cards suggest that this is a safe medium for the storage and transport of bacterial nucleic acids.

Leishmania ( Viannia) braziliensis is the prevalente species infecting patients with tegumentary leishmaniasis from Mato Grosso State, Brazil

The frequency of Leishmania ( Viannia) braziliensis infection among patients of Mato Grosso, Brazil was estimated by polymerase chain reaction—PCR, DNA hybridization and by isoenzyme electrophoresis. Analysis of DNA polymorphism was carried out using random amplified polymorphic DNA-PCR (RAPDPCR) with five different primers. The patients were attended from May 1997 to February 1998 at the Reference Ambulatory for American Tegumentary Leishmaniasis at Júlio Müller University Hospital of the Federal University of Mato Grosso, Brazil. In a first screening by PCR and DNA hybridization 94.1% of 68 patients, from whom parasites were isolated in culture medium, were found to be infected with species of the Le. braziliensis complex. Only four patients (5.9%) were infected with species of Le. mexicana complex. Thirty-three samples of Le. braziliensis complex and three of Le. mexicana complex were typed by isoenzyme analysis as Le. ( V.) braziliensis sensu stricto and Le. (Leishmania) amazonensis, respectively. The predominant species was Le. ( V.) braziliensis, although most of the patients of this study came from the northern area of Mato Grosso, which is part of the Amazonian region of Brazil, where other known species of both subgenus Viannia ( Le. braziliensis complex) and Leishmania ( Le. mexicana complex) are present. The results of RAPD showed higher genetic variability among the Le. ( V.) braziliensis samples from Mato Grosso. The importance of these results concerning the taxonomic status of New World Leishmania, and their implications for both clinical and epidemiological data is discussed.

Common RAPD pattern of Pseudomonas aeruginosa from patients and tap water in a medical intensive care unit

The epidemiology of Pseudomonas aeruginosa infections and colonizations was studied prospectively on a 12-bed medical intensive care unit. Patients were monitored for P. aeruginosa colonization by performing throat swabs or tracheal aspirates on admission and weekly thereafter over a period of 6 months. Cultures of possibly infected sites were taken as clinically indicated. Water samples from all patient care-related tap water outlets were collected in 2-weekly intervals and examined for the presence of P. aeruginosa. Strains isolated from patients and water samples were analysed by serotyping and random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) typing. During the 6-month period, 60 of 143 (42%) water samples contained P. aeruginosa at various levels ranging from 1 to >100 colony-forming units per 100 ml sample. Genotypically, water samples contained 8 different clonotypes. Nine patients had infections due to P. aeruginosa and 7 patients were colonized. Isolates from patients showed a similar distribution of genotypes as did tap water isolates, and strains of identical genotype as patient strains had been isolated previously from tap water outlets in 8 out of 16 (50%) infection or colonization episodes. However, patients also harboured strains not previously isolated from tap water. Thus, in addition to tap water, other environmental or unknown reservoirs appeared to play a role for the epidemiology of P. aeruginosa infections on this ward. However, because tap water played a significant role for strain transmissions, we conclude that intensified water site care is justified.

Host Lewis phenotype‐dependentHelicobacter pyloriLewis antigen expression in rhesus monkeys

Both human and H. pylori populations are polymorphic for the expression of Lewis antigens. Using an experimental H. pylori challenge of rhesus monkeys of differing Lewis phenotypes, we aimed to determine whether H. pylori populations adapt their Lewis phenotypes to those of their hosts. After inoculation of four monkeys with a mixture of seven strains identified by RAPD-polymerase chain reaction, H. pylori Lewis expression was followed in 86 isolates obtained over 40 wk. Host Lewis(a/b) secretion status was characterized by immunological assays. Fingerprints of the predominating strain (J166) were identical in all four animals after 40 wk, but its Lewis phenotype had substantial variability in individual hosts. At 40 wk, J166 populations from two Lewis(a-b+) animals predominantly expressed Lewis(y). In contrast, J166 populations had switched to a Lewis(x) dominant phenotype in the two Lewis(a+b-) animals; a frame shift in futC, regulating conversion of Lewis(x) to Lewis(y), accounted for the phenotypic switch. The results indicate that individual cells in H. pylori populations can change Lewis phenotypes during long-term colonization of natural hosts to resemble those of their hosts, providing evidence for host selection for bacterial phenotypes.

Female-specific DNA sequences in ostriches

Ostrich absence of heteromorphic sex chromosomes, unique sequences or markers located in the ostrich W-chromosome. Random amplified polymorphic DNA (RAPD) fingerprinting was carried out to investigate the sex-specific DNA sequence for sexing in ostrich. One hundred and forty random primers were used for random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). One of these primers, OPAJ-13, produced a sex-specific band only found in tested females, which was isolated and constructed into plasmids for nucleotide sequencing. A 760bp novel female-specific sequence was obtained. Two primers (OstSexOPAJ13-F and -R) were designed according to the cloned female sequence to amplify the female-specific fragment from genomic DNA of ostriches for sexing by PCR. The sex-specific band was represented in females but none were found in the males. This result showed that the sex of ostrich could be easily and effectively identified using the female-specific primers for PCR technique.

Pseudomonas aeruginosa Epidemic Strain Carrying blaSPM Metallo-Beta-Lactamase Detected in Rio de Janeiro, Brazil

The present study was designed to characterize β-lactamase genes and evaluate polymerase chain reaction (PCR) typing for multidrug-resistant Pseudomonas aeruginosa pulsed-field gel electrophoresis (PFGE) genotype A isolates from Rio de Janeiro, Brazil, collected between April 1999 and March 2000 and one additional isolate collected in June 2002. As reported previously, all of the genotype A isolates produced non-characterized metallo-β-lactamase. These isolates (22) were screened for the blaSPM gene by PCR and dot-blotting. Isolates were typed by PCR fingerprinting with primers RAPD-1, 272, 208, 1290, ERIC-1 and ERIC-2. The blaSPM gene was detected in 18 (82%) of the 22 isolates. PCR fingerprinting gave results that correlated with PFGE, except with primer 1290. In Rio de Janeiro and other Brazilian states, nearly all SPM -producing P. aeruginosa isolates belong to a single PFGE type accounting for a large proportion of drug-resistant P. aeruginosa hospital infections. RAPD PCR fingerprinting may be a useful technique to screen for an epidemic multidrug-resistant strain in Brazil.

넙치와 조기의 원산지 판별을 위한 random amplified polymorphic DNA 패턴 연구

본 연구에서 넙치와 조기의 원산지를 판별하기 위한 도구로 RAPD PCR 방법의 가능성을 확인하였다. 넙치는 한국의 주문진 자연산, 통영 양식산, 거제 양식산 그리고 북한 자연산을 실험에 사용하였다. 조기는 한국산과 중국산을 사용하였다. 넙치의 RAPD 패턴에서는 뚜렷하고 일관성이 있는 진단용 띠들을 쉽게 찾을 수 있었다. 조기의 경우에는 유전적인 이질성으로 인하여 각 개체의 RAPD 패턴에서는 일관성이 있는 진단용 띠를 찾기 어려웠지만 각 원산지별로 얻은 RAPD 패턴에서는 가능성이 있는 진단용 띠들을 찾을 수 있었다. The random amplified polymorphic DNA (RAPD) technique was investigated as a potential tool for the origin identification of olive flounder (Paralichthys olivaceus) and redlip croaker (Pseudosciaena polyactis). Olive flounder specimens were collected from North Korea and several locations of South Korea (Jumunjin, Tongyoung and Geoje). Fishes obtained from Tongyeong and Geoje were cultured products. Redlip croaker specimens were collected from South Korea and China. Consistent and distinct diagnostic bands were easily identified in the RAPD patterns of the olive flounder specimens. Although consistent diagnostic bands rarely appeared in the RAPD pattern of redlip croaker specimens because of their genetic heterogeneity, we were able to find potential diagnostic bands in the average RAPD pattern of each origin.

Random amplified polymorphic DNA profiles of Trypanosoma cruzi isolates from chagasic patients with different clinical forms

The genetic variability of 61 Trypanosoma cruzi isolates from 47 chronic chagasic patients of Minas Gerais state was analyzed by random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) using M13-40, lambdagt11-F, and L15996 primers. Cluster analysis by unweighted pair group method analysis was applied to RAPD profiles, and cluster analysis used to verify a possible correlation among different clinical forms of the disease from these patients. The T. cruzi isolates showed distinct grouping on tree topology, with the isolates not being possible to establish a correlation to the clinical forms of Chagas' disease. These data showed that the T. cruzi isolates from these patients would compose a group of populations well correlated genetically.

Geobacillus toebii subsp. decanicus subsp. nov., a hydrocarbon-degrading, heavy metal resistant bacterium from hot compost

A thermophilic, spore-forming bacterial strain L1(T) was isolated from hot compost "Pomigliano Environment" s.p.a., Pomigliano, Naples, Italy. The strain was identified by using a polyphasic taxonomic approach. L1(T) resulted in an aerobic, gram-positive, rod-shaped, thermophilic with an optimum growth temperature of 68 degrees C chemorganotrophic bacterium which grew on hydrocarbons as unique carbon and energy sources and was resistant to heavy metals. The G+C DNA content was 43.5 mol%. Phylogenetic analysis of 16S rRNA gene sequence and Random Amplified Polymorphic DNA-PCR (RAPD-PCR) analysis of L1(T) and related strains showed that it forms within Geobacillus toebii, a separate cluster in the Geobacillus genus. The composition of cellular fatty acids analyses by Gas-Mass Spectroscopy differed from that typical for the genus Geobacillus in that it is lacking in iso-C15 fatty acid, while iso-C16 and iso-C17 were predominant. Isolates grew on a rich complex medium at temperatures between 55-75 degrees C and presented a doubling time (t(d)) of 2 h and 6 h using complex media and hydrocarbon media, respectively. Among hydrocarbons tested, n-decane (2%) was the more effective to support the growth (1 g/L of wet cells). The microorganism showed resistance to heavy metal tested during the growth. Furthermore, intracellular alpha-galactosidase and alpha-glucosidase enzymatic activities were detectable in the L1(T) strain. Based on phenotypic, phylogenetic, fatty acid analysis and results from DNA-DNA hybridization, we propose assigning a novel subspecies of Geobacillus toebii, to be named Geobacillus toebii subsp. decanicus subsp. nov., with the type strain L1(T) (=DSM 17041=ATCC BAA 1004).

Technological and molecular characterisation of enterococci isolated from north–west Italian dairy products

Abstract In the present study, 68 enterococcal isolates collected from dairy products in north–west Italy were characterised by randomly amplified polymorphic DNA-PCR (RAPD-PCR) and by their technologically relevant biochemical properties. After the comparison of RAPD-PCR profiles with the profiles of the enterococcal type strains, isolates were assigned to the species Enterococcus faecalis (35 isolates), E. faecium (27 isolates) and E. durans (6 isolates). Phenotypic identification based on carbohydrate fermentation profile galleries gave different results from RAPD-PCR in 17.6% of the cases (10 E. faecium and 2 E. durans isolates). With respect to biochemical activities, the majority of the strains displayed weak acidification activity in milk. High values for redox activity were detected for 80% of E. faecalis isolates, while E. faecium provided the most lipolytic species. Proteolytic activity was generally low, except for 10 E. faecalis isolates that displayed values ⩾ 0.5 mg tyrosine 5 mL - 1 of milk. None of the isolates carried vanA or vanB (vancomycin resistance) genetic determinants.