# The Role of Microorganisms and Their Antibacterial Compounds in Food Biopreservation
## 1 Introduction
The Potential of Microorganisms in Producing Antimicrobial Compounds and Their Role in Food Biopreservation  
Food biopreservation is based on the rational use of the antimicrobial potential of naturally occurring microorganisms and their metabolites in food. Bioconversion strategies also involve the use of the antimicrobials of the specific strains of microorganisms or their metabolites obtained from natural sources such as bacteria, fungi, plants, or animals. Natural compounds are more active and safer than synthetic compounds, they can deactivate microorganisms and enzymes without compromising sensory or nutritional properties. They can be incorporated into meat, fruits, and vegetables, as well as edible packaging. The main objectives are to extend shelf life by inhibiting food spoilage and increasing food safety by inhibiting the growth of pathogenic bacteria. The application of natural preservatives by the food industry to a certain extent can minimize chemical processing and reduce the intensity of technological treatments [1]. Traditional methods of food preservation, such as fermentation, cooking, drying, smoking, refrigeration, freezing, canning, pasteurizing, dehydrating, freeze-drying, salting, and pickling, comply with consumer expectations [2]. The rising concern about consumers' \"natural\", \"preservative-free\" and at the same time \"high quality\" food makes food manufacturers look for new technological solutions to meet these market requirements. In general, biopreservation meets these requirements. It is defined as the preservation of food using natural or isolated primary and/or secondary metabolites from sources such as bacteria, fungi, plants, and animals. Examples of biopreservatives include bacteria-derivedbacteriocins and lipopeptides as well as oils, plant extracts, or the enzymes of plant and animal origin [3]. Many microorganisms, including probiotic microorganisms, especially lactic acid bacteria (LAB) synthesize various types of biologically active compounds that possess antimicrobial properties [4; 5]. Bacteria produce two types of antimicrobial proteins (AMPs), namely bacteriocins that are synthesized ribosomally and non-ribosomally (no structural encoding genes), e.g., \(\varepsilon\)-poly-L-lysine produced by _Streptomyces albulus_[4]. Their size varies from 10-50 amino acids. Their attributes are low toxicity, thermal stability, and activity over a broad range of pH, which meets the requirements for food processing and preservation [6]. Bacteriocins are the most potent and valuable antimicrobial agents that have attracted the food industry toward their application as food preservatives. Food processing and preservation require different physicochemical processing. Microorganisms synthesizing antimicrobial compounds encounter sometimes extreme conditions, especially when they are used as a starter culture. They must remain viable throughout food manufacturing to produce enough antimicrobial agents to ensure food preservation. Adjunct cultures can be subjected to various harmful factors appearing during transportation, distribution, and storage. It includes environmental stress factors such as temperature and pH changes, oxidative stress, osmotic stress, nutrients depletion or the impact of chemical preservatives such as salt or nitrate and food additives [7]. Antimicrobial activity is associated with cell growth and can be changed with the altering of environmental conditions [8]. Generally, bacteriocins are produced during the exponential growth phase, and in the stationary phase, the synthesis is limited or stopped. Therefore, the optimal physicochemical conditions and food matrix/medium with substrates, such as carbohydrates, nitrogen sources, vitamins, and salts are essential for microorganism antimicrobial activity and adequate bioactive compound production [9].