Determination of the antimicrobial activity of lactic acid bacteria isolated from the Black sea mussel Mytilus galloprovincialis Lamarck, 1819

The present study reports on the determination of the antimicrobial activity of lactic acid bacteria (LAB) isolated from the Black sea mussel Mytilus galloprovincialis Lamarck, 1819. The samples were collected in the period of August 2018 until March 2021. The BIOLOG system was used for microbiological determination. From the mussel M. galloprovincialis Lam. four species of LAB were isolated - Sporolactobacillus kofuensis, Lactobacillus sakei, Streptococcus gallolyticus ss gallolyticus and Lactibacillus brevis. The activity of the strains was determined against test cultures (Escherichia coli 3398, Staphylococus aureus 745, Bacillus subtilis 6633, Salmonella typhimurium 3591, Listeria monocytogens 863 Enterobacter aerogenes 3691, Aspergillus niger, Penicillium claviforme, Saccharomyces cerevisae, Candida albicans 8673 and Candida glabrata 72). Before the analysis for antimicrobial activity, the LAB were cultured in media with different concentrations of sugars - 2, 5 and 10%. The results showed that 4 strains S. kofuensis, L. sakei, S. gallolyticus ss gallolyticus and L. brevis cultured on glucose and oligosaccharides completely lost their activity in all studied variants. Therefore, some carbohydrates (glucose) and oligosaccharides induce the synthesis outside the cell of biologically active molecules, which can probably be attributed to peptides/proteins

Trace metal accumulation in tissues of wedge clams from sandy habitats of the Bulgarian Black Sea coast

The aim of the present study was to carry out an initial screening of trace metals bioaccumulation in soft tissues of the wedge clam (Donax trunculus Linnaeus, 1758) from different localities of the Bulgarian Black Sea coastal area and to evaluate the bioindicator potential of this species. Wedge clams were collected in June and September 2020 from sublittoral sandy habitats at different localities of the Bulgarian Black Sea coast. Soft tissues of individual clams were digested with nitric acid followed by ICP-OES analytical determination. The content of trace metals in the wedge clams differed significantly amongst localities. Higher metal content was present in wedge clams from Sveti Vlas, Shkorpilovtsi, Slanchev Bryag, Ahtopol and Kranevo. The highest values of lead (Pb) (2.51 mg/kg) and cadmium (Cd) (0.32 mg/kg) were found in samples from Sveti Vlas and the highest concentration of copper (Cu) (34.12 mg/kg), iron (Fe) (269.52 mg/kg) and nickel (Ni) (0.32 mg/kg) were detected in wedge clams from Shkorpilovtzi. Maximum content of chromium (Cr) (0.58 mg/kg) was present in samples from Slanchev Bryag, together with high values of Fe. The highest concentration of zinc (Zn) (18.04 mg/kg) together with high values of Cr and Fe were measured in wedge clams from Irakli. In conclusion, the wedge clams from the localities known to have higher coastal inflows and touristic pressures, i.e. Varna, Shkorpilovtzi, Sveti Vlas, Slanchev Bryag and Ahtopol accumulated significantly higher metal elements in their tissues. Only few significant seasonal differences in the concentration of metal elements in wedge clams were present and the observed seasonal variations were probably connected to the hydrological parameters of the ecosystems. The wedge clam D. trunculus is a suitable bioindicator for assessment and monitoring of metal pollution in the Bulgarian Black Sea environment

Study of the dynamics of the microbial communities in the wedge clam Donax trunculus (Linnaeus, 1758) from the Bulgarian aquatory of the Black Sea

In the present work, we investigated the dynamics of the microbial communities in the wedge clam Donax trunculus (Linnaeus, 1758) from the Bulgarian coastal waters of the Black Sea. The samples were collected in the period of January 2020 until December 2022 from Arkutino, Ahtopol, Obzor and Tsarevo. The BIOLOG system was used for microbiological determination. In our investigation were isolated the following microorganisms: Enterococcus cancerogenus, Enterococcus hirae, Escherichia vulneris, Citrobacter farmeri, Acinetobacter gyllenbergii, Enterococcus hirae, Escherichia vulneris, Enterobacter cloacae, Escherichia hermannii, Pseudomonas mendocina, Pseudomonas fulva, Pseudomonas alcaligenes, Pseudomonas putida, Acinetobacter johnsonii, Acinetobacter gyllenbergii, Enterococcus hirae, Escherichia vulneris, Enterococcus gallinarum, Citrobacter sedakii, Pseudomonas putida, Streptococcus lugdunensis, Enterococcus casseliflavus, Vibrio cincinnatiensis, Vibrio alginolyticus, Vibrio parahaemolyticus, Enterococcus hirae, Streptococcus aureus, Staphylococcus lugdunensis and Enterococcus casseliflavus. During the winter period, we detected the presence of Pseudomonas sp. – P. alcaligenes, P. putida, and A. gyllenbergii. In the autumn months we isolated C. sedakii, C. farmeri, A. gyllenbergii, A. johnsonii, P. fulva and E. casseliflavus. In the spring, E. cancerogenus, E. hirae and Pseudomonas mendocina were found. During the summer, the highest biodiversity of microorganisms - E. hirae, E. vulneris, E. cloacae, E. gallinarum, P. putida, V. cincinnatiensis, V. alginolyticus, V. parahaemolyticus, S. aureus, E. hermannii and S. lugdunensis were registered. Although our three-year research showed that some species are permanent and others are transient, we tend to accept the conclusion that there is only a transient microbiota in mussels and it changes depending on environmental conditions or is a result of pollution of the Black Sea

Study of the dynamics of the microbial communities in the wedge clam Donax trunculus (Linnaeus, 1758) from the Bulgarian aquatory of the Black Sea

In the present work, we investigated the dynamics of the microbial communities in the wedge clam Donax trunculus (Linnaeus, 1758) from the Bulgarian coastal waters of the Black Sea. The samples were collected in the period of January 2020 until December 2022 from Arkutino, Ahtopol, Obzor and Tsarevo. The BIOLOG system was used for microbiological determination. In our investigation were isolated the following microorganisms: Enterococcus cancerogenus, Enterococcus hirae, Escherichia vulneris, Citrobacter farmeri, Acinetobacter gyllenbergii, Enterococcus hirae, Escherichia vulneris, Enterobacter cloacae, Escherichia hermannii, Pseudomonas mendocina, Pseudomonas fulva, Pseudomonas alcaligenes, Pseudomonas putida, Acinetobacter johnsonii, Acinetobacter gyllenbergii, Enterococcus hirae, Escherichia vulneris, Enterococcus gallinarum, Citrobacter sedakii, Pseudomonas putida, Streptococcus lugdunensis, Enterococcus casseliflavus, Vibrio cincinnatiensis, Vibrio alginolyticus, Vibrio parahaemolyticus, Enterococcus hirae, Streptococcus aureus, Staphylococcus lugdunensis and Enterococcus casseliflavus. During the winter period, we detected the presence of Pseudomonas sp. – P. alcaligenes, P. putida, and A. gyllenbergii. In the autumn months we isolated C. sedakii, C. farmeri, A. gyllenbergii, A. johnsonii, P. fulva and E. casseliflavus. In the spring, E. cancerogenus, E. hirae and Pseudomonas mendocina were found. During the summer, the highest biodiversity of microorganisms - E. hirae, E. vulneris, E. cloacae, E. gallinarum, P. putida, V. cincinnatiensis, V. alginolyticus, V. parahaemolyticus, S. aureus, E. hermannii and S. lugdunensis were registered. Although our three-year research showed that some species are permanent and others are transient, we tend to accept the conclusion that there is only a transient microbiota in mussels and it changes depending on environmental conditions or is a result of pollution of the Black Sea

A study of the microbiology of the intestinal tract in different species of Teleost fish from the Black Sea

This paper presents a study on the microbial status of different fish species and their habitats in the Bulgarian Black Sea area. The samples were collected in the period of January 2021 until March 2021. The fish species we used in this study were Black Sea turbot (Scophthalmus maximus), round goby (Neogobius melanostomus), shore rockling (Gaidropsarus mediterraneus) and European anchovy (Engraulis encrasicolus). The BIOLOG system was used for microbiological determination. From the different fish species, different species of microorganisms were isolated (using selective nutrient media). From the torbut, we isolated species Enterococcus villorum with 24 × 103 cells in 1 ml, Moraxella nonliquefaciens with 70 × 103 cells in 1 ml and Pseudomonas synxantha with 123 × 103 cells. Pseudomonas putida was isolated from the round goby with 20 × 103 cells in 1 ml. The species Streptococcus entericus with 123 × 103 cells in 1 ml was isolated from the shore rockling. Pseudomonas fulva with 60 × 103 cells in 1 ml was isolated from the European anchovy. A total of 223 × 103 cells in 1 ml of Pseudomonas agarici were isolated from Trachinus draco. Pseudomonas tolaasii with 145 × 103 cells in 1 ml were isolated from Merlangius merlangus. A different species of bacteria of the genus Pseudomonas was found for each of the investigated species of Black Sea fish. Apparently, the species Pseudomonas is characteristic of marine Teleostei and is important for the life and metabolism of these vertebrates. These microorganisms probably are resident species and developed not as result of pollution or environmental change

Seasonal variations of the microflora of wedge clam Donax trunculus (Linnaeus, 1758) from the region of Arkutino (Bulgarian Black Sea aquatory)

The main goal of the present study was to investigate the impact of the state of the environment on the microbiota of the wedge clam Donax trunculus (Linnaeus, 1758) from the region of Arkutino (Bulgarian Black Sea aquatory). The species Enterococcus hirae was isolated during the summer (from May to August). The species P. mendocina prefers the warmer months and the species P. alcaligenes the colder ones. The temperature followed a course of decrease during the period September 2020 to January 2021, followed by a slow increase from February 2021. Comparing May 2020 with May 2021, it became evident that in 2021 the temperature was 1.5 °C lower. We can say that the number of the species P. alcaligenes was twice as high in May 2021. It is likely that this species preferred lower optimum temperatures and constant other parameters. For the species Enterococcus hirae such dependence was not observed - the number remained constant in May, but with increasing temperature the number of microorganisms decreased during the summer months. The species seemed to preferably develop at pH 7.78. The species A. gyllenbergii preferably grows at temperatures between 20.3–25.7 °C and the optimal temperature was 25.7 °C. For C. farmeri the optimum conditions were temperature 26.2 °C and pH 7.3. The species E. vulneris was probably related not only to the increase in water temperature, but also to the anthropogenic factor, as it was found only in July