Characterization of extracellular beta-lactamases from penicillin G-resistant cells of Streptococcus thermophilus

In this study, biochemical properties of two extracellular beta-lactamases produced by penicillin-resistant Streptococcus thermophilus cells were investigated. Both beta-lactamases showed specificity for penicillins but not for cephaloridins. The p-lactamases exhibited different affinities for penicillin G. The one with the higher molecular weight (F1) had a K(m) value of 3.44 mu M and a V(max), value of 8.33, mu mol/min/mg of protein, whereas the beta-lactamase with the lower molecular weight (FII) had a K(m) value of 4.76 mu M and a V(max) value of 3.13 mu mol/min/mg of protein. Both beta-lactamases were inhibited by iodine, copper sulfate, and iron sulfate but not by EDTA. The optimal pH ranged between 6 and 7. and the optimal temperatures were between 40 and 45 degrees C for both enzymes.


Evaluation of high hydrostatic pressure sensitivity of Staphylococcus aureus and Escherichia coli O157 : H7 by differential scanning calorimetry
Alpas, Hami; BOZOGLU, F; KALETUNC, G (Elsevier BV, 2003-11-01)
Differential scanning calorimetry (DSC) was used to evaluate the relative high hydrostatic pressure (HHP) resistances of bacterial strains from Staphylococcus aureus and Escherichia coli O157:H7 in vivo. The total apparent enthalpy change and thermal stability were two DSC parameters used to compare bacterial strains of untreated control and pressure-treated bacteria. DSC thermograms indicated that ribosomal denaturation appears to be a major factor in cell death by both thermal and high pressure treatments...
High hydrostatic pressure induced inactivation kinetics of e. coli o157:h7 and s. aureus in carrot juice and analysis of cell volume change
Pilavtepe, Mutlu; Alpas, Hami; Department of Food Engineering (2007)
The main objective of this study was to determine the pressure induced inactivation mechanism of pressure-resistant Escherichia coli O157:H7 933 and Staphylococcus aureus 485 in a low acid food. Firstly, inactivation curves of pathogens were obtained at 200 to 400 MPa at 40ºC in peptone water and carrot juice. First-order and Weibull models were fitted and Weibull model described the inactivation curves of both pathogens more accurately than first-order model, revealing that food systems could exhibit eithe...
Investigation of cytocidal effect of K5 type yeast killer protein on sensitive microbial cells
Sertkaya, Abdullah; İzgü, Kadri Fatih; Department of Biology (2005)
Some yeasts secrete polypeptide toxins, which are lethal to other sensitive yeast cells, gram-positive pathogenic bacteria and pathogenic fungi. Therefore these are designated as killer toxins. Killer toxins are suggested as potent antimicrobial agents especially for the protection of fermentation process against contaminating yeasts, biological control of undesirable yeasts in the preservation of foods. Moreover they are promising antimicrobial agents in the medical field; due to immune system suppressing ...
Evaluation of hemicellulose as a coating material with gum arabic for food microencapsulation
Tatar, Feyza; Tunc, Merve Tugce; DERVİŞOĞLU, MUHAMMET; Çekmecelioğlu, Deniz; KAHYAOĞLU, TALİP (Elsevier BV, 2014-03-01)
In this study, hemicellulose-based coatings were assessed for use in microencapsulated fish oil. The fish oil emulsions were prepared using the solutions of gum arabic (GA), gum arabic-hemicellulose (GA-HC) and hemicellulose (HC) as the coating materials, amended with maltodextrin as a cheap filler material. The fish oil was then encapsulated with these emulsions using the spray drying method. The effects of the hemicelluloses on the emulsions and the formed microcapsules were evaluated by physical and chem...
Analysis of a bac operon-silenced strain suggests pleiotropic effects of bacilysin in Bacillus subtilis
Ertekin, Ozan; Taskin, Ash Aras; Demir, Mustafa; Karataş, Ayten; Özcengiz, Gülay (Springer Science and Business Media LLC, 2020-04-01)
Bacilysin, as the simplest peptide antibiotic made up of only L-alanine and L-anticapsin, is produced and excreted by Bacillus subtilis under the control of quorum sensing. We analyzed bacilysin-nonproducing strain OGU1 which was obtained by bacA-targeted pMutin T3 insertion into the parental strain genome resulting in a genomic organization (bacA '::lacZ::erm::bacABCDEF) to form an IPTG-inducible bac operon. Although IPTG induction provided 3- to 5-fold increment in the transcription of bac operon genes, n...
Citation Formats
L. Chirica, N. T. Güray, G. C. Gültekin, and F. Bozoglu, “Characterization of extracellular beta-lactamases from penicillin G-resistant cells of Streptococcus thermophilus,” JOURNAL OF FOOD PROTECTION, pp. 896–898, 1998, Accessed: 00, 2020. [Online]. Available: