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  • Autor: Margarita Terentjeva x
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Microorganisms of Grape Berries

Abstract

Grape surface is an unstable habitat that changes greatly according to the stage of grape ripening. Different bacteria and yeasts can colonise the surface of grape berry and the diversity of microorganisms depends on the stage of ripening, pesticide application and health condition. The aim of this study was to study the microflora of the surface of grape berries. Altogether, 19 grape samples from Slovakia were collected. The spread plate method was applied and a 100 μL inoculum of each dilution (10−2, 10−3) was plated on TSA, MEA, and MRS agar for isolation of microorganisms from grapes. Proteins were extracted from cells by ethanol/formic acid extraction procedure. MALDI-TOF Mass Spectrometry was used for identification of microorganisms. In total, 11 genera of Gram-negative bacteria, 11 of Gram-positive bacteria and nine of yeasts were identified. Among 200 isolates, Gram-negative, Gram-positive bacteria and yeasts represented 11%, 27% and 62% of the total number of isolates studied. The most common genera of isolated yeasts were Hanseniaspora (37%), Metschnikowia (31%), and Rhodotorula (10%). The most frequently isolated among Gram-negative bacteria were Acinetobacter (22%), Pseudomonas (22%) and Sphingomonas (13%). The most common genera of Gram-positive bacteria were Bacillus (20%), Lactobacillus (19%), Leuconostoc and Staphylococcus (11%), respectively.

Open access
Antimicrobial Effect of Sage (Salvia officinalis L.) and Rosemary (Rosmarinus officinalis L.) Essential Oils on Microbiota of Chicken Breast

Abstract

The aim of the study was to evaluate the antimicrobial effect of sage and rosemary essential oils (EO) on microbiota of fresh chicken breast. Sample treatments were stored without packaging, vacuum-packaged, vacuum-packaged with EDTA 1.5% v/w, sage and rosemary EO treatment 0.2% v/w. Assessment of food quality was done by anaerobic plate count (APC), and Enterobacteriaceae, lactic acid bacteria (LAB) and Pseudomonas spp. counts a period of 16 days of storage at 4 ± 0.5 °C. Bacterial species were identified with a MALDI TOF MS Biotyper. Antimicrobial activity of isolates against both EO were tested. The APC varied from 2.97 log CFU/g to 6.81 log CFU/g, LAB from 2.35 log CFU/g to 3.36 log CFU/g and Enterobacteriaceae from 0.00 log CFU/g on day 0 to 4.77 log CFU/g with the highest counts on day 16 and in control unpackaged samples. Pseudomonas spp. was found only on days 0, 4, 8, and 12, with counts from 0.00 log CFU/g on day 16 to 2.89 log CFU/g on day 4 in control unpackaged samples. APC were represented by Staphylococcus and Kocuria, LAB with Lactobacillus and Enterobacteriaceae with Buttiauxella, Escherichia, Hafnia, Serratia and Yersinia. The Pseudomonas genus was represented by ten species. The best antimicrobial effect on APC, Enterobacteriaceae, LAB and Pseudomonas was achieved by application of EO. The results suggest the potential use of Salvia officinalis L. and Rosmarinus officinalis L. EOs as natural food preservatives and potential sources of antimicrobial ingredients in the food industry.

Open access
Antibacterial Activity of Melissa officinalis L., Mentha piperita L., Origanum vulgare L. and Malva mauritiana against Bacterial Microflora Isolated from Fish

Abstract

The aim of the present study was to detect the antibacterial activity of medicinal plants against fish microflora. A total of 4 ethanolic extracts of 6 plant species were collected from local environments of Slovakia and screened for antibacterial activity against bacterial microflora. Extracts of Melissa officinalis L., Mentha piperita L., Origanum vulgare L. and Malva mauritiana were used. Bacterial strains were isolated from common bleak (Alburnus alburnus) and common rudd (Scardinius erythrophthalmus) of Latvian origin. All bacterial strains were identified with the Matrix- Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). Among fish microflora, Acinetobacter pittii, A. baumannii, Buttiauxella agrestis, Delftia acidovorans, Enterobacter cloacae, Serratia liquefaciens, Pseudomonas alcaligenes, Ps. oryzihabitans, Staphylococcus epidermidis, St. caprae, Pantoea agglomerans, Lelliottia amnigena, Providencia rettgeri, Escherichia coli and Rahnella aquatilis were identified. It has been shown that all plant extracts exhibit different degrees of antimicrobial activity against the tested bacteria. All bacterial strains in the present study were moderate sensitive to all extracts applied. The strongest antimicrobial effect of Malva mauritiana and Melissa officinalis L. against Pseudomonas oryzihabitans (6.67±1.53 resp. 9.67±0.58 mm) were found. The best antimicrobial activity of Mentha piperita L. was against Staphylococcus epidermis (7.33±0.58 mm) and strongest antimicrobial effect of Origanum vulgare L. was same against two bacterial strains Enterobacter cloacae and Serratia liquefaciens (9.67±0.58 mm).

Open access
Antibacterial Activity of Bees Gut Lactobacilli against Paenibacillus Larvae In Vitro

Abstract

The aim of this study was to evaluate antimicrobial activity of bees gastrointestinal Lactobacillus spp. of against Paenibacillus larvae. Content of the intestinal tract was cultured for isolation of Lactobacillus spp. Gut homogenates were plated on de Man, Rogosa and Sharpe agar (MRS, Oxoid) plates and incubated for 48-72h at 30°C anaerobically. Then, the identification of isolates with MALDI-TOF MS Biotyper was done. The bacterial strains Lactobacillus gasseri, L. amylovorus, L. kunkeei, L. fructivorans, Paenibacillus larvae were isolated from gut content of bees. The disc diffusion method was used for the determination of antimicrobial activities of the Lactobacillus supernatant against two strains of Paenibacillus larvae. The best antimicrobial activity of Lactobacillus against Paenibacillus larvae from gut was found in L. gasseri supernatant. Lesser degree of antimicrobial activity against P. larvae was found in L. kunkeei supernatant. The strongest antibacterial activity against P. larvae CCM 4438 was found in L. gasseri and L. amylovorus and the least antibacterial activity was found in L. fructivorans.

Open access
Determination of Biological and Sensory Profiles of Biscuits Enriched with Tea (Camellia sinensis L.) Powder

Abstract

The aim of this work was to characterise the biological and sensory profile of biscuits enriched with green (1 and 3%) and black tea (1 and 3%) powders. Biscuits without the addition of tea were used as a control. Phenolic concentration, flavonoid concentration, and antioxidant activity were determined spectrophotometrically. Amino acid composition was determined using automatic amino acid analyser AAA 400 and crude fibre content using an Ancom analyser. Sensory profiles were evaluated by comparison of enriched and control biscuit samples. The enriched biscuits showed higher phenolic and flavonoid concentration and antioxidant activity estimated by DPPH and phospholybdenum method in comparison with levels in the control group. The best results for antioxidant activity estimated by DPPH and phosphomolybdenum methods were achieved in biscuits enriched with black tea powder (3%): 2.25 and of 32.64 mg TEAC·g−1, respectively. Total phenolic concentration was 1.16 mg GAE·g−1, and total flavonoid concentration was 0.13 mg QE·g−1. These biscuits had higher concentration of crude fibre in comparison with the control group and the highest concentration (0.64%) was found in biscuits with addition of 3% green tea powder. The amino acid composition in samples, including in the control sample was balanced, with slightly higher concentration of threonine, serine, and methionine in enriched samples, but this parameter was not statistically significant. Biscuits enriched with green and black tea had higher sensory scores for taste, smell and aftertaste.

Open access