Beef as a source of multi-resistant Escherichia coli O157 harbouring transferable plasmid and resistance phenotype

Sixty five strains of enterohaemorrhagic Escherichia coli (EHEC) 0157 isolated frorq frozen imported beef, were examined for presence of plasmid DNA and their susceptibility to seventeen antimicrobial agents. Forty isolates were found to contain plasmid DNA ranging in sizes from 1.38 to 86 megadaltons. All were susceptible to cephalosporin, cepoferazone, kanamycin and nalidixic acid. but multiple resistance to at least four of the antibiotics tested was observed with resistance to bacitracin (100%), methicillin (100%), vancomycin (100%), clindamycin (97%) and novobiocin (92%) most common. In two of the selected multiply-resistant and plasmid containing isolates, resistance was associated with carriage of a 6O megadalton plasmid (EC 1.21) and 1.8, 3, 3.9, 5.1 and 60 megadaltons (EC1.38) plasmids, which were transmissible to the Escherichia coli K12 recipient. It is concluded that imported frozen beef form a reservoir of R plasmid carrying Escherichia coli O157 in the study area

Detection of shiga toxin 1 and 2 (stx1 and stx2) genes in escherichia coli 0157: H7 isolated from retail beef in Malaysia by multiplex polymerase chain reaction (PCR)

Twenty (n=20) beef isolates of Escherichia coli O157:H7 were examined for the detection of Shiga- toxin 1 and 2 (stx1 and stx2) genes by multiplex polymerase chain reaction (PCR) and characterized using Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) fingerprinting. All isolates were obtained from the laboratory of Food Science and Biotechnology, University Putra Malaysia, Serdang, Selangor. In the detection of stx1 and stx2 genes, 14 of isolates (14/20) were positive to stx1 and stx2. 5 isolates (5/20) were positive to stx1 and 1 isolate (1/20) was negative by either of stx1 or stx2 genes. Using RAPD-PCR analysis, two oligonucleotides were chosen because they yielded clearly and reproducible band. There were OPAR8 (5'-TGGGGCTGTC-3') and OPAR20 (5'-ACGGCAAGGA-3'). Subsequently, all 20 isolates of E.coli O157:H7 were subtyped using OPAR8 and OPAR20. Primer OPAR8 produced 8 RAPD-PCR fingerprinting namely P1 to P11. Whereas, OPAR20 produced 16 RAPD-PCR fingerprinting of Q1-Q18. Combination of two primers was analyzed using Unweighted Pair Group Method with Arithmetic mean (UPGMA). Dendogram performed from cluster analysis showed that all the 20 isolates of E.coli O157:H7 differentiated into 20 individual isolates which may suggest the high level of local geographical genetic variation

Volatile compounds and lactic acid bacteria in spontaneous fermented sourdough

The aim of this study is to identify the predominating lactic acid bacteria (LAB) in a spontaneous fermented wheat sourdough. At the same time, an investigation towards volatile compounds that were produced was also carried out. Lactobacillus plantarum has been identified as the dominant species of lactobacilli with characters of a facultative heterofermentative strain. The generated volatile compounds that were produced during spontaneous fermentation were isolated by solvent extraction method, analysed by gas chromatography (GC), and identified by mass spectrophotometer (MS). Butyric acid has been found to be the main volatile compound with relative abundance of 6.75% and acetic acid at relative abundance of 3.60%. Esters that were formed at relatively low amount were butyl formate (1.23%) and cis 3 hexenyl propionate (0.05%). Butanol was also found at low amount with relative abundance of 0.60%. The carbohydrate metabolism of Lactobacillus plantarum may contributed to the production of acetic acid in this study via further catabolism activity on lactic acid that was produced. However, butyric acid was not the major product via fermentation by LAB but mostly carried out by the genus Clostridium via carbohydrate metabolism which needs further investigatio

Leavening ability of yeast isolated from different local fruits in bakery product (Keupayaan Menaik Yis yang dipencilkan daripada Buah-Buahan Tempatan dalam Produk Bakeri)

This study focused on the isolation of yeast from a variety of Malaysian local fruits which can potentially be employed as a leavening agent in bakery products. A total of 6 yeast strains (SKS2, SMK9, SDB10, SRB11, SS12, SM16) were isolated from palm kernel pulp (Cocos nucifera L.), longan (Dimocarpus longan spp. malesianus Leenh), soursop (Annona muricata L.), bamboo shoot (Bambusa vulgaris), snake fruit (Salacca zalacca) and mango (Mangifera indica) using an enrichment procedure which can enhance the growth of yeast colonies and eliminat the fruits worm. The isolates were identified as Saccharomyces cerevisiae, through observation of the yeast cells morphology under microscope, temperature tolerance and fermentative capacity test. The leavening ability of the identified yeasts were examined by fermenting dough. Fermentation proofing was carried out at 30±5°C with 85% humidity for 120 min. The bread doughs were baked at 180°C for 8 min. Results showed that the yeast strains SRB11, SM16, SS12 and SMK9 were able to leaven the highest specific volume of 3.68 cm3/g, 3.41 cm3/g, 3.37 cm3/g and 3.23 cm3/g, respectively. Strain SDB10 and commercial yeast showed less ability with specific volume of 3.02 cm3/g and 2.84 cm3/g, respectively. Thus, the new yeast isolates from local fruits showed much superior with specific volume of more than 3.02 cm3/g

Kesan fermentasi terhadap ciri fizikokimia dan aktiviti antioksida ekstrak mengkudu (Morinda citrifolia L.)

Penyelidikan ini dijalankan untuk mengkaji kesan fermentasi terhadap ciri fizikokimia dan aktiviti antioksida ekstrak mengkudu. Analisis yang dilakukan adalah untuk menentukan nilai pH, keasidan tertitrat, jumlah pepejal terlarut (°Briks), jumlah kandungan fenolik (TPC) dan kuasa penyingkiran radikal bebas (DPPH) melibatkan fermentasi jangka pendek (0, 1 dan 2 minggu) dan jangka panjang (4, 6, 8, 10 dan 12 minggu). Bagi fermentasi jangka pendek, keputusan kajian menunjukkan nilai pH dan kuasa penyingkiran radikal bebas (DPPH) mengalami penurunan yang signifikan (p<0.05) berbanding ekstrak mengkudu segar. Nilai pH, kandungan fenolik jumlah (TPC) dan kuasa penyingkiran radikal bebas (DPPH) menurun secara signifikan (p<0.05) manakala keasidan tertitrat meningkat secara signifikan (p<0.05) bagi fermentasi jangka panjang. Keputusan kajian ini menunjukkan bahawa pH, keasidan tertitrat, jumlah kandungan fenolik dan aktiviti antioksida ekstrak mengkudu mengalami perubahan yang signifikan semasa fermentasi dijalankan. Hanya jumlah pepejal terlarut menunjukkan perubahan yang tidak signifikan (p<0.05) setelah menjalani fermentasi. Berdasarkan keputusan yang diperoleh, fermentasi buah mengkudu didapati tidak menghasilkan kesan yang positif kepada aktiviti antioksida dan jumlah kandungan fenolik bagi ekstrak buah mengkudu dengan fermentasi menghasilkan pengurangan aktiviti antioksida dan jumlah kandungan fenolik yang ketara

Detection of shiga toxin 1 and 2 (stx1 and stx2) genes in escherichia coli O157:H7 isolated from retail beef in Malaysia by Multiplex Polymerase Chain Reaction (PCR)

Twenty (n=20) beef isolates of Escherichia coli O157:H7 were examined for the detection of Shiga- toxin 1 and 2 (stx1 and stx2) genes by multiplex polymerase chain reaction (PCR) and characterized using Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) fingerprinting. All isolates were obtained from the laboratory of Food Science and Biotechnology, University Putra Malaysia, Serdang, Selangor. In the detection of stx1 and stx2 genes, 14 of isolates (14/20) were positive to stx1 and stx2. 5 isolates (5/20) were positive to stx1 and 1 isolate (1/20) was negative by either of stx1 or stx2 genes. Using RAPD-PCR analysis, two oligonucleotides were chosen because they yielded clearly and reproducible band. There were OPAR8 (5’-TGGGGCTGTC-3’) and OPAR20 (5’-ACGGCAAGGA-3’). Subsequently, all 20 isolates of E.coli O157:H7 were subtyped using OPAR8 and OPAR20. Primer OPAR8 produced 8 RAPD-PCR fingerprinting namely P1 to P11. Whereas, OPAR20 produced 16 RAPD-PCR fingerprinting of Q1-Q18. Combination of two primers was analyzed using Unweighted Pair Group Method with Arithmetic mean (UPGMA). Dendogram performed from cluster analysis showed that all the 20 isolates of E.coli O157:H7 differentiated into 20 individual isolates which may suggest the high level of local geographical genetic variation

Molecular typing of Salmonella weltevreden and Salmonella chincol by pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR)

Genomic DNA of Salmonella weltevreden (10 isolates from poultry, two isolates each from raw vegetables and river water) and S. chincol (15 isolates from poultry) were characterized by pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) analysis. These isolates originated from a single location in Kajang, Selangor. The results of the PFGE and ERIC-PCR were analysed and comparisons were made using GelCompar software. ERIC-PCR with primers ERIC1R and ERIC2 discriminated the S. weltevreden into five clusters and two single isolates and S. chincol into two clusters and two single isolates at a similarity level of 80%, respectively. PFGE produced a single cluster and eight single isolates for S. weltevreden, and one cluster and 11 single isolates for S. chincol at a similarity level of 80% after digestion with the restriction enzyme XbaI, respectively. These results demonstrate that both PFGE and ERIC-PCR are suitable tools for molecular typing of the isolates examined