In this article, the presence and physiological characteristics of lactic acid bacteria (LAB) isolated from traditionally made cheese from Southeastern Serbia were examined. Three samples, from different households, were obtained in spring. The screening of antagonistic potentials, using agar‐well diffusion method, was evaluated. Briefly, three different genera of LAB (Enterococcus [32%], Lactococcus [53%], and Lactobacillus [15%]) were identified. The members of the genus Enterococcus were Enterococcus faecium and Enterococcus faecalis. The member of genus Lactococcus was Lactococcus lactis subsp. lactis var. diacetylactis. The members of genus Lactobacillus were Lactobacillus fermentum, Lactobacillus plantarum, and Lactobacillus paracasei subsp. paracasei. The antagonism of LAB on the growth of Escherichia coli ATCC 25922, Proteus mirabilis ATCC 12453, Klebsiella oxytoca KGPMF1, Klebsiella ornithinolytica KGPMF8, and Aeromonas hydrophila was examined. All tested isolates inhibited the growth of at least one indicator strain with growth inhibition zone from 10 to 21 mm. Results indicated that LAB demonstrated the potential of food biopreservation. Practical applications Traditionally made cheeses represent excellent source of unexplored microflora, especially of autochthonous lactic acid bacteria (LAB). In cheese from Sokobanja, the isolated LAB genera were Lactobacillus sp., Lactococcus sp., and Enterococcus sp. Also, the physiological activity of LAB, as well as their interaction with enterobacteria, which also was isolated from the mentioned cheese, was investigated. The results of this study demonstrated potential of LAB to interact agonistically with the growth of enterobacteria, which was important due to the well‐known fact that enterobacteria could affect the organoleptic properties of cheese. LAB showed potential of food biopreservation. Further investigation should include antagonistic potential related to food‐borne bacteria and the mechanisms of action.

In this study, we determined the concentration of total phenols, flavonoids, tannins, and proanthocyanidins in the water, diethyl ether, acetone, and ethanol extracts of Agrimonia eupatoria L. We also investigated the antioxidant activity of these extracts using two methods [2,2-diphenyl-1-picrylhydrazyl (DPPH) and reducing power] and their in vitro antimicrobial (antibacterial and antifungal) activity on some selected species of bacteria and fungi. In addition, the effects of the acetone and water extracts on the inhibition of biofilm formation of Proteus mirabilis and Pseudomonas aeruginosa were investigated using the crystal violet method. The concentration of total phenols was measured according to the Folin-Ciocalteu method and the values obtained ranged from 19.61 mgGA/g to 220.31 mgGA/g. The concentration of flavonoids was examined by the aluminum chloride method and the values obtained ranged from 20.58 mgRU/g to 97.06 mgRU/g. The total tannins concentration was measured by the polyvinylpolypyrrolidone method and the values obtained ranged from 3.06 mgGA/g to 207.27 mgGA/g. The concentration of proanthocyanidins was determined by the butanol-HCl method and the values obtained ranged from 4.15 CChE/g to 103.72 CChE/g. Among the various extracts studied, the acetone extract exhibited good antioxidant activity (97.13%, as determined by the DPPH method). The acetone extract was active in the absorbance value range from 2.2665 to 0.2495 (as determined by the reducing power method). The strongest antimicrobial activity was detected on G bacteria, especially on probiotic species, and the acetone extract demonstrated the highest activity. Biofilm inhibitory concentration required to reduce biofilm coverage by 50% values for acetone extract was 4315 μg/mL for P. mirabilis and 4469.5 μg/mL for P. aeruginosa. The results provide a basis for further research of this plant species.

In this paper, the presence of enterobacteria in autochthonous cheese from Southeast Serbia (Sokobanja), made in the traditional way, was investigated. The samples from different households, was taken during the summer and the autumn. Chemical and physical characteristics of samples (water content, fat content, acidity, pH, and sodium chloride content) were examined. In the analyzed samples of cheese, four different genera of family Enterobacteriaceae (Klebsiella [65%],, and Enterobacter [5%]) were identified. The members of genus Klebsiella were Klebsiella oxytoca, Klebsiella pneumoniae, and Klebsiella ornithinolytica, while in the genus Escherichia only one species, Escherichia coli was identified. Besides, two species of the genus Serratia, Serratia odorifera and Serratia marcescens biogp 1, and one species of the genus Enterobacter, Enterobacter gergoviae, were identified. Biochemical characteristics, proteolytic and lipolytic activity, sensitivity to streptomycin, chloramphenicol, and tetracycline were, also, determined. According to the rapid latex agglutination test, of the four E. coli isolates, two isolates belong to serotype E. coli O157. Practical applicationsThe results of this study contribute to better understanding of unexplored microflora of cheese from Sokobanja. The isolated genera were Klebsiella sp., Escherichia sp., Enterobacter sp., and Serratia sp. with twenty identified species. It is well known that bacteria from family Enterobacteriaceae could affect organoleptic properties of cheese. Bacteria isolated from cheese from Sokobanja mostly did not manifest proteolytic and lipolytic activity. The most number of isolates were susceptible to tested antibiotics. Further researches may contribute to better understanding of interaction between enterobacteria and lactic acid bacteria in autochthonous cheeses.

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The presence, biochemical and physiological characteristics of Lactobacillus and Lactococcus species isolated from traditionally made cheese from Southeastern Serbia (Sokobanja), was investigated. The screening of their antimicrobial potentials, using agar‐well diffusion method, and the ability of biofilm formation, using crystal violet method, was evaluated. The cheese samples, from different households, were obtained during the summer and the autumn. Chemical characteristics of cheese samples were examined. The members of genus Lactobacillus were: Lb. fermentum, Lb. brevis, and Lb. plantarum. The members of genus Lactococcus were: Lc. lactis subsp. lactis and Lc. lactis subsp. lactis biovar. diacetylactis. The antagonism of Lactobacillus and Lactococcus isolates on the growth of some Gram‐negative bacteria, isolated from the same cheese, was examined. The zones of growth inhibition ranged from 10 to 26 mm. The ability of biofilm formation of isolates was strains‐specific. Lactobacillus (KGPMF 28, KGPMF 29, KGPMF 35) and Lactococcus (KGPMF 23 and KGPMF 26) isolates demonstrated the potential for further investigation in natural preservation of food. Practical applications Lactic acid bacteria, which can be found in traditional dairy products, presents unique and autochthonous microflora responsible for fermentation and quality of dairy products. These bacteria often have a great potential in natural food preservation, but their number and diversity are depending of season, vegetation, and the nutrition of animals. In this paper, the seasonal differences in bacterial community (especially community of lactobacilli and lactococci) between cheese samples, were investigated. In addition, the antagonism against some enterobacteria, which can affect the hygienic safety of cheese, was screened. Also, it was showed that some isolates had the ability of biofilm formation. Further investigation need to include the potential of isolates to be uses like probiotic or starter cultures.

In this paper, we investigated the presence of enterobacteria in cheese from Southeastern Serbia which was produced in a traditional way. The samples from different households were collected in spring. Chemical and physical characteristics of samples (water content, fat content, acidity, pH, and sodium chloride content) were examined. In the analyzed samples of cheese, we found one genus of family Enterobacteriaceae, Escherichia sp. The genus Escherichia sp. includes only one species, Escherichia coli. We also determined biochemical characteristics, proteolytic and lipolytic activities, the ability to form a biofilm, sensitivity to streptomycin, chloramphenicol, and tetracycline. According to the rapid latex agglutination test, two isolates belong to serotype E. coli O157.Practical applicationsThese results contribute to a better understanding of the presence of enterobacteria in unexplored microbiota of cheese from Sokobanja. E. coli is the only member of enterobacteria that appears in the samples collected in spring. Since E. coli is among the indicators of contamination, it does not demonstrate the ability to change the organoleptic properties of cheese. E. coli does not exhibit lipolytic or proteolytic activity, but it demonstrates sensitivity to antibiotics. The bacteria showed no ability to form biofilm. Further research should focus on finding the sources of contamination, as well as on the interaction of E. coli with other members of the cheese microbiota.

Streptococcus uberis is an environmental bacterium responsible for bovine mastitis. It is occasionally described as a human pathogen. In our study, the isolation was undertaken of lactic acid bacteria from a local cheese from Southeastern Serbia, produced in a traditional way. S. uberis (7 isolates) and S. agalactiae (1 isolate) were isolated from the cheese samples taken in the summer. the biochemical and physiological characteristics of the isolates were examined. Using tetracycline, chloramphenicol, novobiocin and rifampicin, the antibiotic susceptibility of the isolates was evaluated. the results demonstrated that all the isolates were susceptible to all the tested antibiotics, with a growth inhibition zone from 36-48 mm. also, the antagonism was examined of S. uberis kGPMF1-7 and S. agalactiae kFPMF8 isolates on the growth of Escherichia coli atCC 25922, Proteus mirabilis atCC 12453, Klebsiella oxytoca kGPMF1, Klebsiella ornithinolytica kGPMF8 and Aeromonas hydrophila, as indicator stains. the results were compared with the activities of chloramphenicol, streptomycin and tetracycline on the tested indicator stains. the strongest antagonism was demonstrated by all Streptococcus isolates on the growth of K. oxytoca kGPMF1 (growth inhibition zone from 12-20 mm) and the A. hydrophila (growth inhibition zone from 13-20 mm). When these results were compared with the results of the sensitivity of tested indicator stains to antibiotics, S. uberis kGPMF1-7 and S. agalactiae kGPMF8 isolates showed a moderate antagonistic effect. Due to the specific way cheese is made in from Sokobanja, these isolates probably originate from cows' udders.

ABSTRACT. In this study, the effects of environmental factors (different media, temperature, pH, salt and sugar concentrations) on the planktonic growth, biofilm formation and formed biofilm of Escherichia coli KGPMF 16 and Escherichia coli KGPMF 17 were investigated. Tested bacteria were isolated from traditionally made cheese produced in Southeastern Serbia (Sokobanja region). The influence on planktonic growth, biofilm formation and formed biofilm was determined using spectrophotometric method. The limiting factors for the planktonic growth and biofilm formation were temperature of 4 °C and all tested concentrations of salt. The growth of tested bacteria was higher in media enriched with lactose than in media containing glucose. TSB was more congenial media to the planktonic growth of bacteria than MHB broth. None of the tested bacteria demonstrated the ability to form biofilm at 4 °C and 44 °C. Only E. coli KGPMF 17 showed ability to form biofilm in TSB at 37 °C. Different concentrations of salt, glucose and lactose exhibited inhibitory effect on biofilm formation, but all tested concentrations of lactose showed stimulating effect on formed biofilm of E. coli KGPMF 17. These results contribute to better understanding of the effects of environmental factors on the development of E. coli in cheese.