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Aditi Singh,1 Sudhakar Padmesh,1 Manish Dwivedi,1 Irena Kostova2 1Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Lucknow, 226028, India; 2Department of Chemistry, Faculty of Pharmacy, Medical University, Sofia, 1000, BulgariaCorrespondence: Aditi Singh, Email asingh3@lko.amity.edu; singh.aditi00@gmail.comAbstract: Bacteria survive on any surface through the generation of biofilms that provide a protective environment to grow as well as making them drug resistant. Extracellular polymeric matrix is a crucial component in biofilm formation. The presence of biofilms consisting of common opportunistic and nosocomial, drug-resistant pathogens has been reported on medical devices like catheters and prosthetics, leading to many complications. Several approaches are under investigation to combat drug-resistant bacteria. Deployment of bacteriophages is one of the promising approaches to invade biofilm that may expose bacteria to the conditions adverse for their growth. Penetration into these biofilms and their destruction by bacteriophages is brought about due to their small size and ability of their progeny to diffuse through the bacterial cell wall. The other mechanisms employed by phages to infect biofilms may include their relocation through water channels to embedded host cells, replication at local sites followed by infection to the neighboring cells and production of depolymerizing enzymes to decompose viscous biofilm matrix, etc. Various research groups are investigating intricacies involved in phage therapy to mitigate the bacterial infection and biofilm formation. Thus, bacteriophages represent a good control over different biofilms and further understanding of phage-biofilm interaction at molecular level may overcome the clinical challenges in phage therapy. The present review summarizes the comprehensive details on dynamic interaction of phages with bacterial biofilms and the role of phage-derived enzymes – endolysin and depolymerases in extenuating biofilms of clinical and medical concern. The methodology employed was an extensive literature search, using several keywords in important scientific databases, such as Scopus, Web of Science, PubMed, ScienceDirect, etc. The keywords were also used with Boolean operator “And”. More than 250 relevant and recent articles were selected and reviewed to discuss the evidence-based data on the application of phage therapy with recent updates, and related potential challenges.Graphical Abstract: Keywords: phage, extracellular polymeric substance, biofilm, antibiotic resistance, mitigating strategy, phage cocktail, phage lysins, depolymerases

Water quality is essential for maintaining good health, and preventing and controlling various diseases. The aim of this study was to determine the quality of drinking water from three water sources in the region of Targovishte - drinking water from the water supply network, water from a mineral spring, and spring water from the village of Razboyna. The investigated water samples from the Targovishte region comply with the controlled physicochemical parameters on the drinking water quality: colour on the Rublev scale, smell, turbidity, pH, oxidability, general hardness, chloride content, nitrite, sulphate, and iron. The results showed that the waters comply with all controlled microbiological parameters on drinking water quality: determination of Escherichia coli and coliform bacteria; determination of enterococci; determination of sulphite-reducing anaerobes spores; determination of the total number of aerobic and facultatively anaerobic bacteria; determination of Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Yoghurt is a traditional dairy product that is present on our table every day. Its quality, which is determined by the values of its physical, chemical, and microbiological indicators, is monitored by both producers and various public and scientific organisations. The aim of the present study is a comparative analysis and qualitative assessment of three commercially available Bulgarian yoghurts. After the first day of their purchase and during their storage for ten and 20 days, the variation of the main indicators - titratable acidity, pH, syneresis and total lactic acid bacteria count (Lactobacillus bulgaricus and Streptococcus thermophilus) was monitored. The samples were also subjected to organoleptic evaluation, which included determination of surface, colour, coagulum type, texture on cutting, consistency on breaking, taste and aroma. The data showed that all three yoghurt samples retained their quality characteristics and were edible throughout the storage period. [ABSTRACT FROM AUTHOR]

The propolis is a unique natural product that has been used by people in traditional medicine since ancient times. The aim of the present work is to determine the chemical composition and antioxidant activity of propolis, originating in 1993 from North-Eastern Bulgaria. The stored raw material has unchanged physical and chemical parameters - appearance, color, smell, content of mechanical impurities, wax content (19.6%), oxidizability index (16), active acidity (5.5), acid number (42.3 mg KOH/ g), ester number (152 mg KOH/g), boiling point (107°C). The data show that 40 components were identified, representing 99.14% of the total composition. The main components (over 2%) are: chrysin (18.37%), pinobanksin-3-etenoate (13.38%), pinobanksin-3-propanote (11.38%), pinobanksin-3-pentanoate (9.36%), squalene (6.36%), galangin (5.91%), dihydrochrysin (4.11%), pinobanksin-3-butenoate (2.94%), caffeic acid isomer 2 (2.74%), and (E)-sinapic acid (2.23%). Total phenols were 23.91 mg GAE/g. Antioxidant activity was determined by three methods: DPPH (1874.12 mMTE/g), FRAP (1039.18 mMTE/g), and ABTS (1539.52 mMTE/g). The antioxidant effect was monitored against goose fat and sunflower oil. The obtained data show maximally preserved physical parameters, chemical composition and antioxidant activity of the propolis sample stored for more than 30 years, which can be used in various products, an object of future research.