27 research outputs found
Identification and bioactivity of native strains of Bacillus thuringiensis from grain-related habitats in Turkey
No full textHarsa, Hayriye Sebnem/0000-0001-6794-299X; Tarhan, Ozgur/0000-0001-7084-6253WOS: 000254869500003A native collection of Bacillus thuringiensis (Bt) strains originated from grain-related habitats in Turkey was characterized according to serotype, cry1 gene content, and bioactivity against Ephestia kuehniella (Lepidoptera: Phycitidae) and Spodoptera littoralis (Lepidoptera: Noctuidae). Twenty-three different scrotypes as well as 24 unknown serotypes were obtained from 56 positively agglutinated strains with previously characterized antisera. Most common serovars were sotto, kim, and tochigiensis with the percentages of 14, 14, and 13, respectively. Among the cry1 gene-positive 36 strains, cry1E (100%), cry1 Aa (94%), cry1 Ac (92%), and cry1D (83%) genes were the most abundant. Bioactivity tests with 56 Bt strains carrying cry1, cry2, and/or cry9 genes indicated that all of them resulted in growth retardation or inhibition of larvae of both E. kuehniella and S. littoralis; however, only one strain, 85PPb (serovar morrisoni), caused high mortality in both insects (84%. and 100%, respectively). Different crystal morphology was observed for the strain 85PPb and the standard strain B. thuringiensis subsp. morrisoni. Finally, no correlation was found among serotype, cry gene content and biotoxicity of Bt strains in the collection. (C) 2008 Elsevier Inc. All rights reserved
Optimization of the associative growth of novel yoghurt cultures in the production of biomass, β-galactosidase and lactic acid using response surface methodology
No full textThe associative growth of Streptococcus thermophilus 95/2 (St 95/2) and Lactobacillus delbrueckii ssp. bulgaricus 77 (Lb 77) isolated from the Toros mountain region of Turkey was investigated with respect to lactic acid, biomass and β-galactosidase enzyme production using response surface methodology (RSM). The ratio (St 95/2:Lb 77) of the strains and media formulation had significant effect on all responses (p < 0.001). The predicted enzyme activity (2.14 U mL-1), lactic acid (22.50 g L-1) and biomass (7.11 g L-1) production at optimum conditions were very close to the actual experimental values (2.14 U mL-1, 22.94 g L-1 and 7.86 g L-1, respectively). The optimum conditions were to use these cultures in a ratio of 1.66:1.62 (St 95/2:Lb 77) in a medium containing whey (5%), corn steep liquor (4%), potassium phosphate (2%) and peptone (2%) at 43 °C for 8 h. The associative growth provided 6.4% and 39% more β-galactosidase activity and 8.73% and 44% more lactic acid compared with the results obtained using pure St 95/2 and Lb 77 strains, respectively.TÜBİTAK TOVAG 1040270; DPT-2005 K 12057
Microencapsulation of L. acidophilus NRRL B-4495 in whey Protein-Pullulan Microparticles: Influence of Pullulan Concentration and Outlet Temperature
No full textBiochemical and thermal properties of β-galactosidase enzymes produced by artisanal yoghurt cultures
No full textβ-Galactosidases, produced by pure and mixed cultures of Streptococcus thermophilus 95/2 (St 95/2) and Lactobacillus delbrueckii ssp bulgaricus 77 (Lb 77) isolated from the Toros mountain region of Turkey, were characterised with respect to their biochemical and thermal properties. Optimum pH and temperature for maximum activity were determined and these enzymes were stable in the pH range 7-9 and in the temperature range 20-37 °C, retaining 80-90% of their initial activities. The inactivation energies of β-galactosidase from Lb 77, St 95/2 and mixed culture (Lb 77 and St 95/2) were 51.3, 44.0 and 48.3 kcal mol-1, respectively. Moreover, thermodynamic (ΔG, ΔS, ΔH) and kinetic constants (Km and Vmax) were determined and effects of metal ions were investigated. As a result, these enzymes could be considered as potential candidates for lactose hydrolysis of milk and milk products. © 2009 Elsevier Ltd. All rights reserved.TÜBİTAK (TOVAG 104O270) and State Plan Organization (DPT-2005 K 120570
EDITORIAL: Functional Food Products & Ingredients For Gut Health
No full textGUEST EDITOR'S COMMENTAR
Prevalence and Antibiotic Resistance of Foodborne <i>Staphylococcus aureus</i> Isolates in Turkey
No full textIn this study, 154 Staphylococcus aureus isolates were detected from 1070 food samples (14.4%) collected from seven cities in Turkey. Antimicrobial susceptibility testing against 21 antibiotics was performed by agar disk diffusion method, and those isolates resistant to any antibiotic were further analyzed to determine minimum inhibitory concentration by E-test and polymerase chain reaction analysis of vanA and mecA genes. According to disk diffusion test results, a total of 139 strains were resistant to at least one tested antibiotic, with 39 (25.3%) strains being multidrug resistant (MDR) and the other 15 strains being susceptible to all antibiotics. Penicillin G, linezolid, erythromycin, and tetracycline took up 71.4%, 23.4%, 18.2%, and 15.6% of the tested strains, respectively. In addition, all of the strains were susceptible to vancomycin, oxacillin, cefoxitin, and imipenem. Only one strain (S158B) was resistant to both teicoplanin and cefazolin. On the other hand, the presence of vanA and mecA genes was not detected in the strains. Pulsed-field gel electrophoresis analysis was used to identify genetic-relatedness of the MDR strains. It is noteworthy that some strains from different sources showed 100% homology; however, some of MDR strains were found unrelated with 60% or less homology. The high diversity observed in pulsed-field gel electrophoresis results indicated the possible contamination of S. aureus from different sources and routes.The Scientific and Technological Research Council of Turkey (Turkey) (Project number:107T266
Microencapsulation of L. acidophilus NRRL B-4495 in whey Protein-Pullulan Microparticles: Influence of Pullulan Concentration and Outlet Temperature
No full textSpray drying technique is one of the oldest methods adapted to many industrial areas to protect bioactive components. In this study, pH and heat tolerance of encapsulated probiotic Lactobacillus acidophilus NRRL B-4495 cells were investigated. Additionally, influence of process conditions including outlet temperature and pullulan concentration on spray drying process was observed. Scanning electron microscopy images showed that incorporation of pullulan higher than 2.0 % in wall matrix created huge amount of fibrous particles. Spherical microcapsules having smooth surface were formed with 2.0 % pullulan (WPI-pullulan4.5:1) formulation leading to an improvement of barrier properties of microcapsules. Moreover, incorporation of pullulan improved the survival rate to 94.21 % after spray drying. Results suggested that decreasing outlet temperature exhibited much higher cell survivals up to 92.68 %. However, between outlet temperatures, significant differences (p≤0.05) in moisture content and recovery of final product indicated that more effective encapsulation of L. acidophilus NRRL B-4495 cells was achieved at 50 °C. During spray drying, due to dehydration and high heat, cytoplasmic membrane of bacterial cells undergo damage and therefore, microencapsulation in WPI-pullulan blend by spray drying provided the highest survival against heat stress at 45 ºC. Moreover results showed that encapsulated cells survived at minimum desired level (7 log CFU/g) at pH 2.0 in contrast to free cells
Microencapsulation of a potential probiotic Lactiplantibacillus pentosus and its impregnation onto table olives
No full textThis study aimed to demonstrate some probiotic properties of Lactiplantibacillus pentosus NRRL B-227 and impregnate the strain onto the table olive surfaces. In this respect, antioxidative ability, antibiotic resistance, and survivability after simulated digestion tests were carried out. Microencapsulation was performed using xylan and whey protein concentrate (WPC) using the water-in-oil emulsion technique to maintain cell viability. A vacuum impregnation process was performed to coat olive surfaces with L. pentosus. This strain demonstrated 71.6% DPPH radical scavenging activity and exhibited paramount resistance to antibiotics. The viable cell count of microencapsulated L. pentosus was found as 8 log CFU/g after 72 weeks of storage. After exposure to the simulated oral phase, 1-log reduction was detected, and gastric phase conditions led to a 3-log reduction of viability of microencapsulated as well as non-microencapsulated cells. The viability of microencapsulated L. pentosus on the surface of olives was also evaluated for one-month, and viable cell count was >= 6 log CFU/g. In the light of these findings, L. pentosus with antibiotic and digestion fluids resistant and antioxidant properties were successfully microencapsulated within xylan-WPC complex. Table olives can be considered as a suitable carrier for beneficial microorganisms that satisfies with the expectations of regulations for functional foods
Developing a functional lozenge with microencapsulated Lactiplantibacillus pentosus to improve oral and dental health
No full textIn this study, a functional lozenge was developed by using microencapsulated Lactiplantibacillus pentosus NRRL-B 227. Antimicrobial activity of L. pentosus was determined to find out the efficiency on cariogenic and pathogen microorganisms that are known to cause dental caries and gum diseases. Streptococcus mutans is a well-known cariogenic strain, which easily converts sugars to acids and exert adverse effects on dental health. Candida albicans is an opportunistic pathogen when body resistance is weak, it becomes dominant in the mouth, causing disruption of oral health. Within this context, by applying several methods (e.g. broth microdilution, disc diffusion, agar overlay and planktonic culture assays), L. pentosus showed antibacterial and antifungal activities against S. mutans ATCC 25175 and C. albicans DSMZ 5817, respectively. Thus, three different lozenge formulation were produced such as; CL control formulation without cells, CPL formulation containing micro encapsulated cells and FPL formulation containing free cells. The microbiological, physicochemical and sensorial studies were carried out for all formulations stored at 4 degrees C and 25 degrees C. Among these, CPL was found to be more stable than FPL, since microencapsulation with Pullulan/WPC water-in-oil emulsion play a protective role. L. pentosus viability has been lost after 1 month at 25 degrees C, however the viability was maintained without significant reduction at 4 degrees C in case of CPL samples. In the light of findings, lozenge formulation incorporated with L. pentosus can be considered as potential antimicrobial to improve oral health and therefore may become a promising candidate to contribute to the range of functional food products
