The role of probiotics on slowing down the aging process.

The gastrointestinal (GI) microbiota is one of the most complex ecosystems in nature that are mainly comprised of bacteria and other microbes like fungi, protozoa, and viruses. More than 1000 bacterial species have been reported in the gut microbiome, of which most of these species belong to Firmicutes (31.1%), Proteobacteria (29.5%), Actinobacteria (25.9%), or Bacteroidetes (7.1%) phylum. A symbiotic relationship, which plays a critical role in host health, exists between intestinal microflora and its host. With aging, the intestinal microbiota profile changes are observed, generally characterized by the decrease in biodiversity, carriage of commensals, and enrichment of opportunistic pathogens. The dysbiosis associated with aging in the gut microbiota increases the risk of several diseases. Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host” and play crucial functions in improving gut health and disease in all age groups, particularly the elderly induvial. This review focuses on the promising effects of probiotics on slowing down the aging process, treating age-related diseases, and improving the quality of life in light of the current clinical studies.

Prevalence, antibiotic resistance, and enterotoxin production of Staphylococcus aureus isolated from retail raw beef, sheep, and lamb meat in Turkey.

The main objective of this study was to isolate and identify Staphylococcus aureus from retail raw red meat samples and evaluate their enterotoxin gene and antibiotic resistance profiles. A total of 452 retail raw meat samples, including beef (n = 200), sheep (n = 125), and lamb (n = 127) randomly purchased from various supermarkets and butchers in Ankara between July 2019 and November 2020, were tested for the prevalence of S. aureus. The S. aureus strain was identified using morphological and molecular (16S rRNA and nuc gene) methods. Moreover, nine Staphylococcal enterotoxin (SE) genes were screened using polymerase chain reaction. Antibiotic resistance of S. aureus was determined using the phenotypic disc diffusion method. The overall prevalence of S. aureus among screened samples was 21.23%. Additionally, 65.62% of S. aureus strains contained SE gene regions. The predominant SEs in the S. aureus strains were sea (50.79%), followed by sed (25.39%) and seb (23.80%). However, sec, see, seg, seh, sei, and sej genes were never detected. A substantial proportion (40-100%) of the isolates were found resistant to kanamycin, telithromycin, penicillin G, streptomycin, erythromycin, cloxacillin, ampicillin, pristinamycin, nalidixic acid, azithromycin, and ciprofloxacin. Multi-drug resistance (MDR) was observed in 96.87% of the S. aureus strains. These results show a low prevalence of S. aureus in raw red meat samples in Turkey. However, a high rate of SEA raises serious health concerns. Due to the high levels of MDR observed in this study, there is a need to strictly control antibiotic use in animals in Turkey.

Antimicrobial Resistance of Enterococcus Species Isolated from Chicken in Turkey.

The aim of the present work was to provide information about Enterococcus strains isolated from pre-packaged chicken samples in Ankara (Turkey), focusing on their prevalence, phenotypic and genotypic characteristics, and antibiotic resistance. We report the first study on the occurrence of antibiotic resistant enterococci in pre-packaged chicken samples in Ankara. A total of 97 suspicious enterococcal isolates were identified from 122 chicken samples. All isolates were identified to species level by phenotypic and molecular methods. In the 16S rDNA sequence analysis, Enterococcus faecium (61.85%) and Enterococcus faecalis (38.15%) were found to be the most frequently detected Enterococcus spp. Of the 97 isolates tested for hemolytic activity, 12.37% enterococcal strains were ß-hemolytic. ß-Hemolysin was most prevalent among E. faecium (58.33%) compared to E. faecalis (41.66%). Disk diffusion method was used for determining of antibiotic resistance. The analysis of the antimicrobial resistance of the 97 Enterococcus isolates revealed that the resistance to kanamycin (98.96%), rifampicin (80.41%) and ampicillin (60.82%) was most frequent. Furthermore, resistance to erythromycin (38.14%) and ciprofloxacin (34.02%) was also observed. The frequencies of resistance to tetracycline (9.27%), penicillin G (8.24%), and chloramphenicol (3.09%), gentamicin (2.06%) and streptomycin (1.03%) were low. None of the isolates was resistant to vancomycin. Multi-drug resistance was found in 97.93% of Enterococcus strains. E. faecium strains showed a more resistant phenotype than E. faecalis strains according to the antibiotic resistance levels. The results of this study indicated that chicken meat is a potential reservoir for the transmission of antibiotic resistance from animals to humans.

Phenotypic and genotypic identification of lactic acid bacteria isolated from traditional pickles of the Çubuk region in Turkey.

A total of 152 lactic acid bacteria (LAB) were isolated from pickles produced in the Ankara-Çubuk region. These isolates were clustered into eight groups on the basis of their phenotypic characteristics including cell morphology, CO2 production from glucose, growth at 10 and 45 °C, growth in 6.5 % NaCl, and growth at pH 9.6. API 50 CH carbohydrate fermentation test, 16S ribosomal RNA (rRNA) sequence analysis, and sodium dodecyl sulfate-acrylamide gel electrophoresis (SDS-PAGE) whole-cell protein profile analysis were also performed for precise identification of the isolates at the species level. Molecular identification revealed that the most prevalent LAB species involved in pickle fermentation were Pediococcus ethanolidurans (46 isolates, 30.3 %), Lactobacillus brevis (37 isolates, 24.3 %), Lactobacillus plantarum (37 isolates, 24.3 %), and Lactobacillus buchneri (15 isolates, 9.9 %). Other LAB were found in minor frequencies such as Pediococcus parvulus (8 isolates, 5.3 %), Lactobacillus namurensis (6 isolates, 3.9 %), Lactobacillus diolivorans (1 isolate, 0.7 %), Lactobacillus parabrevis (1 isolate, 0.7 %), and Enterococcus casseliflavus (1 isolate, 0.7 %). When results of phenotypic and genotypic identification methods were compared, differences in the species distribution of LAB associated with pickles were defined between the API and the 16S rRNA sequencing. The API 50 CHL test coincided with the 16S rRNA results in 71 out of the 152 tested isolates, indicating that API gave unreliable identification results. A clear correlation could not be found between the results of whole-cell SDS profiles and 16S rRNA sequencing. Therefore, molecular characterization by 16S rRNA sequencing was considered to be the most reliable method for identifying isolates. The results presented in this work provide insight in to the LAB population associated with traditional Çubuk pickles and constitute a LAB strain resource for further studies involving the development of starter cultures.

Thermal inactivation kinetics of Lactococcus lactis subsp. lactis bacteriophage pll98-22.

Survival curves of Lactococcus lactis subsp. lactis bacteriophage pll98 inactivated by heat were obtained at seven temperature values (50-80 degrees C) in M17 broth and skim milk. Deviations from first-order kinetics in both media were observed as sigmoidal shapes in the survival curves of pll98. An empirical model with four parameters was used to define the thermal inactivation. Number of parameters of the model was reduced from four to two in order to increase the robustness of the model. The reduced model produced comparable fits to the full model. Both the survival data and the calculations done using the reduced model (time necessary to reduce the number of phage pll98 six- or seven- log10) indicated that skim milk is a more protective medium than M17 broth within the assayed temperature range.

A kinetic study on the plasmid stability of three Lactococcus lactis strains.

The plasmid stability of three wild type Lactococcus lactis strains and their mutants was investigated at different incubation time and temperatures in two different media [M17 broth and reconstituted skim milk (RSM)]. The results showed that both incubation times and temperature are effective on plasmid loss. The plasmid profiles of wild type strains exhibited 8 to 9 distinct plasmid species with molecular weights from 2.1 to 24.0 kb. Lactose fermentation ability was found to be encoded by 22.2 (strain U70), 23.6 (strain U29) and 24.0 (strain U52) kb plasmids in the wild type strains, respectively. The stabilities of the plasmids were explained by applying a second-order polynomial modeling system. Reasonable fittings were obtained for the model and the adjusted regression coefficients (R ( 2 ) (adj)) were between 0.76 and 0.99 for the overall data. Overall, it was found that incubation time had the most profound effect on plasmid stability, with plasmid loss occurring after 72 h, while temperatures in the range of 15-40 degrees C also induced plasmid instability.

Identification of adsorption inhibition, restriction/modification and abortive infection type phage resistance systems in Lactococcus lactis strains.

98 Lactococcus lactis strains were isolated from traditional fermented milk products in Turkey tested against 60 lactococcal lytic phages to determine their resistance levels. While 82 L. lactis strains were sensitive against lactic phages at different levels, 16 L. lactis strains showed resistance to all phages tested. Types of phage resistance among 16 L. lactis strains were identified as phage adsorption inhibition in eight strains, restriction/modification in six strains and abortive infection (heat sensitive phage resistance) in two strains, using three broad-spectrum phages phi pll 98-32, phi pld 67-42 and phi pld 67-44.