Browsing by Author "Tamer, AÜ"

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    A study on the effects of chilling on the microbiological quality of poultry carcasses and surface decontamination with lactic acid
    Tosun, H; Tamer, AÜ
    Effects of immersion chilling on the microbiological quality of poultry carcasses and cross contamination of Salmonella were studied. Levels of aerobic mezophilic bacteria, coliform, Escherichia coli and the incidence of Salmonella were determined prechill and postchill. The level of coliform and E. coli were reduced by immersion chilling (P < 0.01). The reduction of aerobic mezophilic bacteria was not significantly significant (P > 0.05) but there was an increase in Salmonella incidence in carcasses exiting the immersion chiller indicating that this may be the point of most significant cross contamination in broiler processing plants. Experiments on microbial decontamination of poultry carcasses with lactic acid were performed. The microbial levels of poultry carcasses were reduced significantly by lactic acid treatment (P < 0.05). Treatment with lactic acid (1%) resulted in a 1.259, 1.685 and 2.023 logaritmic unit reduction in colony forming units of aerobic mezophilic bacteria, coliform and E. coli. Other treatments with lactic acid (3%) resulted in a 2.502, 3.876 and 3.820 logaritmic unit reduction in colony forming units of aerobic mezophilic bacteria, coliform and E. coli compared with the control samples. Salmonella was not isolated from decontaminated broiler carcasses with 1% and 3% of lactic acid solutions. Lactic acid can be used eliminate Salmonella from poultry carcasses and extend the shelf life of processed broilers. However undesirable organoleptic characteristics may occur when it is used at high concentrations.
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    Antimicrobial and Antioxidant Activities of Mycelia of 10 Wild Mushroom Species
    Kalyoncu, F; Oskay, M; Saglam, H; Erdogan, TF; Tamer, AÜ
    Antimicrobial and antioxidant activities of mycelia obtained from 10 wild edible mushrooms-Armillaria mellea, Meripilus giganteus, Morchella costata, Morchella elata, Morchella esculenta var. vulgaris, Morchella hortensis, Morchella rotunda, Paxillus involutus, Pleurotus eryngii, and Pleurotus ostreatus-were investigated. For determination of antimicrobial activities of these mushrooms, ethanol extracts were examined with 11 test microorganisms by the agar well diffusion method. P. ostreatus and M. giganteus were the most active species against both bacteria and yeast. Antioxidant properties of ethanol extracts were studied by the 1,1-diphenyl-2-picrylhydrazyl free radical scavenging method. Among the mushroom extracts, M. elata showed the most potent radical scavenging activity. This research has shown that these 10 wild macrofungi have potential as natural antioxidants and antibiotics.
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    Isolation, characterization and numerical taxonomy of novel oxalate-oxidizing bacteria
    Sahin, N; Gökler, I; Tamer, AÜ
    The present work is aimed at providing additional new pure cultures of oxalate utilizing bacteria and its preliminary characterization for further work in the field of oxalate-metabolism and taxonomic studies. The taxonomy of 14 mesophilic, aerobic oxalotrophic bacteria isolated by an enrichment culture technique from soil, rhizospheres, and the juice of the petiole/stem tissue of plants was investigated. Isolates were characterized with 95 morphological, biochemical and physiological tests. Cellular lipid components and carotenoids of isolates were also studied as an aid to taxonomic characterization. All isolates were Gram-negative, oxidase and catalase positive and no growth factors were required. In addition to oxalates, some of the strains grow on methanol and/or formate. The taxonomic similarities among isolates, reference strains or previously reported oxalotrophic bacteria were analysed by using the Simple Matching (S-SM) and Jaccard (S-J) Coefficients. Clustering was performed by using the unweighted pair group method with arithmetic averages (UPGMA) algorithm. The oxalotrophic strains formed five major and two single-member clusters at the 70-86% similarity level. Based on the numerical taxonomy, isolates were separated into three phenotypic groups. Pink-pigmented strains belonged to Methylobacterium extorquens, yellow-pigmented strains were most similar to Pseudomonas sp. YOx and Xanthobacter autotrophicus, and heterogeneous non-pigmented strains were closely related to genera Azospirillum, Ancylobacter, Burkholderia and Pseudomonas. New strains belonged to the genera Pseudomonas, Azospirillum and Ancylobacter that differ taxonomically from other known oxalate oxidizers were obtained. Numerical analysis indicated that some strains of the yellow-pigmented and nonpigmented clusters might represent new species.
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    Taxonomic position of Pseudomonas oxalaticus strain Ox1T (D5M 1105T) (Khambata and Bhat, 1953) and its Description in the genus Ralstonia as Ralstonia oxalatica comb. nov.
    Sahin, N; Isik, K; Tamer, AÜ; Goodfellow, M
    Pseudomonas oxalaticus strain Ox1(T) (= DSM 1105(T)), which was described as an oxalate-decomposing bacterium, was reinvestigated to clarify its taxonomic position. 16S ribosomal DNA sequence comparisons demonstrated that this species is phylogenetically related to the species of the genus Ralstonia and represents a new species. The result of the DNA-DNA hybridization value was supported in this placement. Strain Ox1(T) is closely related to Ralstonia eutropha with a less than 60% DNA-DNA hybridization value. The new name Ralstonia oxalatica comb, nov. is proposed to strain Ox1(T), on the basis of these results and previously published data for the G+C content of the genomic DNA and the phenotypic characters.