Z. Kerényi

7004062220

Publications - 7

Tejsavbaktérium-izolátumok egyes probiotikus tulajdonságainak in vitro vizsgálata

Judit Süle Zoltán Hatvan Z. Kerényi László Varga

Publication Name: Elelmiszervizsgalati Kozlemenyek

Publication Date: 2023-01-01

Volume: 69

Issue: 1

Page Range: 4337-4349

Description:

No description provided

Open Access: Yes

DOI: 10.52091/EVIK-2023/1-2-HUN

In vitro evaluation of certain probiotic properties of lactic acid bacteria isolates

Judit Süle Zoltán Hatvan Z. Kerényi László Varga

Publication Name: Elelmiszervizsgalati Kozlemenyek

Publication Date: 2023-01-01

Volume: 69

Issue: 1

Page Range: 4350-4363

Description:

Bacteria carrying genes responsible for antibiotic resistance cannot be used in food production. For this reason, exploring the antibiotic resistance profile of probiotic candidates and the antimicrobial substances they produce are essential for probiotic strain selection. The aim of this study was to develop and evaluate additional elements of a complex in vitro test system for rapid and efficient selection of a large number of putative probiotic isolates. In a previous work, we had tested bacterial strains (n=217) isolated from Transylvanian raw sheep milk, cultured sheep milk, and sheep cheese samples and we reduced the sample number to a total of six Gram-positive, non-hemolytic, catalase-negative, well-aggregating, good acid and bile acid tolerating strains. In this research, we investigated the antibiotic resistance and antimicrobial production capacity of the pre-selected strains (n=6). The antimicrobial activity of the isolates was determined by the agar well diffusion assay. Strains E15, E66, E173, E198, and E216 were found to inhibit the growth of both Salmonella Enteridis ATCC 13076 and the control strain (i.e., Lactobacillus acidophilus ATCC 4356). Antibiotic resistance tests were performed by the agar disk diffusion method. All six isolates belonging to the species of Levilactobacillus brevis and Lactiplantibacillus plantarum were found to be resistant to several antibiotics and, therefore, cannot be used for the manufacture of commercial probiotic products. In conclusion, our in vitro test system proved to be capable of effectively screening out unsafe isolates.

Open Access: Yes

DOI: 10.52091/EVIK-2023/1-2-ENG

In vitro tesztrendszer alkalmazása probiotikus baktériumtörzsek szelektálására

Judit Süle Zoltán Hatvan Z. Kerényi László Varga

Publication Name: Elelmiszervizsgalati Kozlemenyek

Publication Date: 2022-06-30

Volume: 68

Issue: 2

Page Range: 3904-3915

Description:

No description provided

Open Access: Yes

DOI: 10.52091/EVIK-2022/2-4-ENG

Relationship between total cell counts and exopolysaccharide production of Streptococcus thermophilus T9 in reconstituted skim milk

E. Korcz Z. Kerényi László Varga

Publication Name: Lwt

Publication Date: 2021-08-01

Volume: 148

Issue: Unknown

Page Range: Unknown

Description:

The main objective of this study was to establish a correlation between total bacterial count (TBC) and exopolysaccharide (EPS) production in a specific Streptococcus thermophilus strain. TBC was determined based on real-time quantitative polymerase chain reaction (qPCR) standard curves of S. thermophilus T9 cultured in reconstituted skim milk. EPS yields were measured following isolation and purification steps using a dextran standard curve. The relationship between TBC of and EPS production by S. thermophilus T9 was analyzed alongside these standard curves. The results showed that EPS yield reached 36.6 ± 0.8 mg L−1 following 6 h of incubation. Over the same period, the streptococcal counts measured by qPCR increased from 4.71 ± 0.15 to 7.52 ± 0.09 log10 TBC mL−1. Overall, EPS biosynthesis has been shown to be a growth-related trait in S. thermophilus T9 (R2 = 0.991). In conclusion, the monitoring of TBC may provide an insight into the mechanism of EPS production and, therefore, its use can be recommended for this purpose and for EPS quantification. To our knowledge, this is the first research that has associated qPCR-based TBC with EPS yield in S. thermophilus.

Open Access: Yes

DOI: 10.1016/j.lwt.2021.111775

Serratia fajok jellemzése, valamint Serratia marcescens kvalitatív kimutatása nyers és pasztőrözött tejből polimeráz láncreakción alapuló vizsgálati módszerrel

E. Korcz Z. Kerényi László Varga

Publication Name: Elelmiszervizsgalati Kozlemenyek

Publication Date: 2021-01-01

Volume: 67

Issue: 2

Page Range: 3441-3452

Description:

No description provided

Open Access: Yes

DOI: 10.52091/EVIK-2021/2-4-HUN

Characterization of serratia species and qualitative detection of serratia marcescens in raw and pasteurized milk by an analytical method based on polymerase chain reaction

E. Korcz Z. Kerényi László Varga

Publication Name: Elelmiszervizsgalati Kozlemenyek

Publication Date: 2021-01-01

Volume: 67

Issue: 2

Page Range: 3453-3464

Description:

Serratia species are opportunistic pathogenic microorganisms primarily known as nosocomial infectious agents, which can also cause food quality problems. The appearance of the extracellular pigment-producing Serratia marcescens in cow’s milk causes its red discoloration, posing a challenge to the dairy industry and food certification laboratories. The detection of the bacterium by conventional procedures based on microbiological methods is time-consuming and labor-intensive, and in many cases does not lead to satisfactory results due to the competitive inhibitory effect of the accompanying microflora. Following the analysis of the relevant literature, the published endpoint PCR methods and the primers used for the detection of S. marcescens were evaluated in in silico and in vitro assays, and then the procedure was tested on farm milk samples. Using the method, a total of 60 raw and pasteurized milk samples were analyzed, more than half of which (i.e., 32) were identified as S. marcescens positive. The significance of our work is mainly represented by the application of the published test methods in food industry practice. Our results highlight to the importance of detecting this bacterial species.

Open Access: Yes

DOI: 10.52091/EVIK-2021/2-4-ENG

Dietary fibers, prebiotics, and exopolysaccharides produced by lactic acid bacteria: Potential health benefits with special regard to cholesterol-lowering effects

E. Korcz Z. Kerényi László Varga

Publication Name: Food and Function

Publication Date: 2018-06-01

Volume: 9

Issue: 6

Page Range: 3057-3068

Description:

The gastrointestinal (GIT) microbiota, which plays a crucial role in human health, is influenced by a number of factors including diet. Consumption of specific dietary ingredients, such as dietary fibers and prebiotics, is an avenue by which the microbiota can be positively modulated. These substances may also reduce serum cholesterol levels through various mechanisms. Interest has increased in methods of reducing blood cholesterol level, because dyslipidemia is recognized as a contributory risk factor for the development of cardiovascular diseases. Several drugs have been developed for the treatment of hypercholesterolemia; however, undesirable side effects were observed, which have caused concerns about their long-term therapeutic use. Alternatively, many nonpharmacological approaches were tested to reduce elevated serum cholesterol levels. Dietary fibers and prebiotics have particularly beneficial effects on the GIT microbiome, and can also reduce serum cholesterol level through various mechanisms. Lactic acid bacteria (LAB) are potentially capable of synthesizing different polysaccharides, e.g. exopolysaccharides (EPS), which may play a role as prebiotics. LAB-based EPS have the potential to affect the gastrointestinal microbiome and reduce cholesterol. However, as dietary fibers comprise a complex group of substances with remarkably diverse structures, properties, and impacts, EPS also differ greatly and show a multitude of beneficial health effects. This review discusses the current knowledge related to the effects of dietary fibers and prebiotics on the human GIT microbiome, the prebiotic properties of EPS produced by LAB, and the health-promoting benefits of these polymers with special emphasis being given to cholesterol lowering.

Open Access: Yes

DOI: 10.1039/c8fo00118a