# The Role of Microorganisms and Their Antibacterial Compounds in Food Biopreservation
## 6 New Technologies of Food Bioconversion as an Alternative to Artificial Preservation
The cell-free supernatant contains a number of low- and high-molecular-weight bacterial metabolites with synergistic antimicrobial activity. [PERSON] et al. report that films supplemented with the _Lactobacillus sakei_ NRRL B-1917 cell-free supernatant on beef inoculated with _Escherichia coli_ ATCC 25922 or _Listeria monocytogenes_ Scott A exhibited antimicrobial activity. Sensory assessment did not show a significant impact of the addition of postbiotics to the packaging material on the quality of stored products [129]. The strategy of combining bioconversion with other preservation methods to achieve a synergistic effect seems to be the most valuable. The combination of preservation methods should consider the physiology and behavior of microorganisms in foods. An integrated intelligent approach to food preservation methods to create safe, stable, and nutritious food is the concept of the effective preservation of foods called hurdle technology [130; 131; 132]. For the past 45 years, hurdle technology, initially a combination of physicochemical preservation methods, has evolved into a multitarget preservation approach for food, concerning the physiology and behavior of microorganisms in foods. According to [PERSON], the disturbance of the homeostasis of microorganisms is the key phenomenon that may complicate food preservation [133; 134]. Bacteriocins can be employed in combination with novel non-thermal preservative methods such as pulsed electric field, high hydrostatic pressure, ultrasound waves or irradiation, and modified atmospheric packaging [135; 136; 137; 138]. The synergistic effect of such combinations was confirmed in various food matrices. Bacteriocins can be more effective in influencing the permeability of the outer membrane, thus increasing their effectiveness against microorganisms [139; 140; 2]. Another promising idea is the genetic modification of the naturally available bacteriocins. Bioengineering offers the creation of new bacteriocins with desired food industry properties, like augmented antimicrobial activity [47]. An example of genetic modification is nisin. The substitution of nisin amino acid generated a novel variant nisin Z, which has better solubility, thermal stability, and a wider range of pH activity along with broadened antibacterial activity against Gram-negative food-borne pathogens like _Shigella, Pseudomonas_, and _Salmonella_ species. The genetical engineering allowed the production of more effective chimeric bacterioxins within diverse groups, including nisin, pedicoxins, and enterocins [43]. The recombinant DNA technology enables, for example, the fusion of two genes to generate increased production of more efficacious bacteriocins. Furthermore, there are possibilities of chemical bacteriocin synthesis allowing for the modification of amino acid composition, which could help to find compounds of better properties feasible for food preservation [80]. Another promising approach is the combined use of bacteriocins and bacteriophages as food biopreservatives [141]. In the study of [PERSON] et al., phage mixtures were combined with nisin, showing a reduction in more than two log units of the _Listeria_ population [142]. Another study by [PERSON] et al. also shows the superiority of a combination of enterocin AS-48 and phage P100 against _L. monocytogenes_ in raw salmon and smoked salmon [143]. New technologies of food bioconversion, especially the idea of natural antimicrobial biodegradable packaging, are in concordance with ecological consumers' expectations. The use of one method of food preservation is associated with different limitations, especially at the industrial level. For example, the excessive use of chemical compounds can create potential health risks, high temperatures can decrease nutrient value and sensory organoleptic quality, or natural bioconversion alone can be insufficient for food preservation due to the low capacity of antimicrobial agent productions.