Microbial biofilm is an aggregation of microbial species that are either attached to surfaces or organized into an extracellular matrix. Microbes in the form of biofilms are highly resistant to several antimicrobials compared to planktonic microbial cells. Their resistance developing ability is one of the major root causes of antibiotic resistance in health sectors. Therefore, effective antibiofilm compounds are required to treat biofilm-associated health issues. The awareness of biofilm properties, formation, and resistance mechanisms facilitate researchers to design and develop combating strategies. This review highlights biofilm formation, composition, major stability parameters, resistance mechanisms, pathogenicity, combating strategies, and effective biofilm-controlling compounds. The naturally derived products, particularly plants, have demonstrated significant medicinal properties, producing them a practical approach for controlling biofilm-producing microbes. Despite providing effective antibiofilm activities, the plant-derived antimicrobial compounds may face the limitations of less bioavailability and low concentration of bioactive molecules. The microbes-derived and the phytonanotechnology-based antibiofilm compounds are emerging as an effective approach to inhibit and eliminate the biofilm-producing microbes.

Problem statement: Only limited information exists on nutrients in salmonoids meat in Bulgaria, which may to be different and vary to a greater extent than the nutrient composition of other fish items. The present paper is aimed to determine the proximate composition, macro and trace elements of Atlantic salmon`s meat. These data could be helpful in judging the value of nutrient composition data as a base for dietary recommendations. Organisms: 12 species of Atlantic salmon (Salmo salar). Approach: The aim of this study was to determine the proximate composition and levels of iron, potassium, sodium, calcium, phosphorus, magnesium, copper, selenium and zinc in Atlantic salmon cultivated for the first time in Bulgaria. The content of protein, fat and ash and concentrations of iron, potassium, sodium, calcium, phosphorus, magnesium, copper, selenium and zinc were determined by automatic systems and electro thermal atomic absorption spectrometry (ETAAS) after microwave digestion. Mean values and their respective coefficients of variation were calculated from the measured concentrations. Conclusion: In order to provide an accurate overview and to be able to calculate reliable dietary intakes, it is important to know the fish composition data.

Farmed mussels accumulate contaminants from their production environment rather than releasing them into water. This study reveals potential health risks associated with selenium, cadmium, mercury, and lead resulting from the consumption of mussels (Mytilus galloprovincialis) cultured along the coasts of Türkiye and Bulgaria. The concentrations of Se and toxic trace metals were measured by inductively coupled plasma mass spectrometry (ICP-MS). The detection limits (LOD) were 0.100, 0.015, 0.025, and 0.180 µg/kg for Se, Cd, Hg, and Pb, respectively. The mean Se concentrations were between 1.305 and 1.957 µg/g, and toxic metals were below the maximum limits. Due to Turkish and Bulgarian consumers’ limited mollusk consumption, mussels could only provide a maximum of 7.35% of the daily Se need. THQ and TTHQ of Se, Cd, and methyl-Hg were below 1, indicating that farmed mussels were safe for consumption. Percent PTWI values were calculated only for Cd and MeHg, as the PTWI value for Pb was discarded by the authorities and not determined for Se. Accordingly, weekly mussel consumption did not pose any risks. The margin of exposure approach was used to evaluate Pb intake. MOE-SBP and MOE-NE were significantly higher than 10, designating no significant health risks. Long-term consumption of mussels also does not pose a carcinogenic risk regarding the TR index calculated between 10⁻⁵ and 10⁻⁶ for Pb. Positive HBV_Se (10.13–37.27) indicated that Se in mussels overcame Hg-related potential health concerns. Consequently, mussels grown in Türkiye and Bulgaria did not pose a risk for human consumption, based on current risk analysis methods.

In the Bulgarian aquaculture sector, focusing research efforts on the technical specifications of the cultivation of African catfish (Clarias gariepinus) is important due to the need for more information. We aimed to assess the impact of light intensities on prolactin and cortisol levels as stress markers in African catfish. Fish were acclimated over an appropriate period to the short photoperiod (16D and 8L) and then distributed randomly to three groups, each separated by sex. Fish exposed to different light intensities (63, 51, and 40 lux, respectively) were followed for 45 days by lux meter. Blood samples were collected from the caudal vein using a 2 ml K2EDTA-coated syringe. A laser fluorescence reader assayed plasma prolactin and cortisol. The pituitary was removed from anesthetized fish and fixed for histological examinations. The results of our study suggest that increasing light intensity increases prolactin and cortisol levels in African catfish.

Proteins are crucial molecules of biological processes with particular functions. They are marginally stable biomolecules and are readily prone towards denaturation due to the occurrence of different stressed conditions in solution, dried, or frozen forms. Some factors, such as pH, storage containers, temperature, buffer systems, and repetitive freezing and thawing, play a critical role in maintaining the stability of proteins. This review summarizes the pragmatic methods for the storage of purified proteins, preserving an ample amount of biological activity. It elucidates the simple and empirical means of preventing proteolytic denaturation, microbial contamination, low-temperature storage, and the inclusion of several kinds of stabilizing agents. Various types of protease inhibitors are known to reduce proteolytic degradation with improved protein storage stability. The addition of antimicrobials (e.g., thiomersal and sodium azide) and filtration are used to prevent microbial contamination. Low temperature and freeze-drying (lyophilization) are also known as significant methods for protein storage. Additionally, the inclusion of stabilizing agents, such as osmolytes, reducing agents, ionic stabilizers, specific substrates, ligands, and exogenous proteins, and concentrating diluted proteins are effective strategies for reducing the degradation and enhancing the shelf-life of proteins. Several stabilizing agents, such as -mercaptoethanol, EDTA, EGTA, glycerol, and ethylene glycol, enhance protein stability with less to no damage. Thus, these strategies provide substantial directions for maintaining the integrity of proteins, facilitating both investigational reproducibility and commercial viability of protein-based products.

Waste non-standard fish combined with wheat bran filler in ratio 60:40 were used for production of new non-traditional protein component called Ribotricin. The aim of this study was to elucidate the effects of the new protein component Ribotricin on growth performance, feed utilization and feed ingredients digestibility of carp (Cyprinus carpio L., 1758) fish. The experiment (90 days) involved 160 carp reared in eight concrete tanks with an initial average weight of 0.046 ± 8.04 g in (RT) tank, and fish with an initial average weight of 0.047 ± 6.52 g in (FM) tanks. The experimental carp were equally divided into two groups of 80 (four replicates of 20 carp each). The obtained results at the end of the experiment, showed no significant differences between the groups` Body Weight (BW), Feed Conversion Ratio (FCR), Specific Growth Rate (SGR), Protein Efficiency Ratio (PER) (p> 0.05). Based on the obtained data, we can conclude that Ribotricin (RT) can be used as fish meal substitution in the diets of carp fish without adverse effects on the measured parameters.