Stephany Toschkova

Currently, there are no data and studies from Lake Vaya, Burgas city, on the status and quantity of microplastic (MP) particles in fish. This is the first study on the abundance, morphotype, size, polymer type, and color of MP in Gambusia affinis and Liza saliens from the lake. In this study, we also investigated the distribution of MPs in different parts of the fish. Within each morphological group of MPs, three size classes were recognized: 25–100 µm, 100–200 µm, and 200–500 µm. Microplastics were found in all studied fish tissues except for caviar, but in different proportions of pellets, fibers, and fragments. In our study, fibers were the most isolated, followed by irregularly shaped MPs—fragments. Two types of polymers were found—PET and PA. There are currently no studies in Lake Vaya that assess the risk of ingestion of microplastics for fish health and human health. Research shows that almost all aquatic environments worldwide are at risk of MP contamination. Laboratory and field studies highlighted that fish are particularly susceptible to MP ingestion, although freshwater species have been studied less than marine ones. The results of our study suggest that consumption of fish from Lake Vaya may expose citizens to risk.

Currently there is no data and studies from Lake Vaya, Burgas city on the status and quantity of microplastic (MP) particles in fish. This is the first study on the abundance, morphotype, size, polymer type and color of MP in Gambusia affinis, and Liza saliens from the Lake. We also investigated the distribution of MPs in different parts of the fish. Within each morphological group of MPs, three size classes were recognized: 25-100 µm, 100-200 µm and 200-500 µm. Microplastics were found in all studied fish tissues except for caviar, but in different proportions of pellets, fibers and fragments. In our study, fibers were the most isolated, followed by irregularly shaped MPs – fragments. Two types of polymers were found - PET and PA. There are currently no studies in Lake Vaya that assess the risk of ingestion of microplastics for fish health and human health. Research shows that almost all aquatic environments worldwide are at risk of MP contamination. Laboratory and field studies highlighted that fish are particularly susceptible to MP ingestion, although freshwater species have been studied less than marine ones. The results of our study suggest that consumption of fish from Lake Vaya may expose citizens to risk.

The accumulation of microplastics in the world oceans is one of the main global problems of the modern world. The Black Sea is the main source of seafood for people from several countries, including Bulgaria. The pollution of the Black sea is a result of various factors, especially anthropogenic. The present study demonstrated detailed MPs contamination of five fish species important for the commercial fishing (Garfish, Мullet, Knout goby, Pontic shad and Mediterranean horse mackerel) collected from the Sozopol area on the Bulgarian Black Sea coast. Within each microplastic morphological group, three size classes were recognized: 100-200 µm, 25-100 µm, and ≤ 25 µm. Microplastics were found in the soft tissues of all studied specimens but in a different ratio of pellets, fibers and fragments. Generally, the pellets were the most often registered particles, followed by irregularly-shaped fragments, whereas fibers were less numerous. The dominant part of the isolated plastics are made of polyethylene (PE), and polyethylene terephthalate (PET). Our results pointed out serious pollution with plastic particles in the Bulgarian Black Sea aquatory, which in the future may seriously affect the health of the fish population and also human health.

The accumulation of microplastics in the world oceans is one of the main global problems of the modern world. The Black Sea is the main source of seafood for people from several countries, including Bulgaria. The pollution of the Black sea is a result of various factors, especially anthropogenic. The aim of this study was to determine the presence and accumulation of microplastics in the Black Sea mussel Mytilus galloprovincialis L., 1819, harvested from different locations along the northern Bulgarian Black Sea coast. Within each microplastic morphological group, three size classes were recognized: 100-200 μm, 25-100 μm, and ≤ 25 μm. Microplastics were found in the soft tissues of all studied specimens but in a different ratio of pellets, fibers and fragments. Generally, the pellets were the most often registered particles, followed by irregularly-shaped fragments, whereas fibers were less numerous. The dominant part of the isolated plastics are made of polyethylene (PE), and polyethylene terephthalate (PET). Our results pointed out serious pollution with plastic particles in the Bulgarian Black Sea aquatory, which in the future may seriously affect the health of the mussel population and also human health.

An exopolysaccharide (EPS) was isolated from Lactobacillus plantarum Ts and purified by size exclusion chromatography train. L. plantarum showed the highest production (9.4 ± 0.8 g/l) of EPS. Furthermore, L. plantarum was cultured in medium with volume of 5 L and the EPS was extracted by ethanol precipitation. By HPLS analysis demonstrated, that the EPS has two fractions - polymer and olygomer. The molecular mass of the EPS from both fractions is respectively 8.3x104 Da for the greater pic and 5.0x102 Da. Fourier transform infrared spectroscopy analysis showed the presence of hydroxyl and carboxyl groups and glycosidic linkages. TLC analysis indicated that the EPS was a heteropolymer composed of fructose, and sucrose as monomeric constituent units. The strain L. plantarum and pathogenic E. coli 3398, St. aureus 745, B. subtilis 6633, S. typhimurium 3591, L. monocytogenes 863 and E. aerogenes 3691 were tested for their growth utilizing the EPS from L. plantarum as the sole carbon source for its possible use as a prebiotic. L. plantarum exhibited growth in the EPS supplied medium compared with sucrose as carbon source, whereas the pathogenic strains did not grow in the EPS-supplied medium. In vitro evaluations showed that, like other reported polysaccharides, this EPS displayed significant prebiotics properties.