Use of Phage Cocktail for Improving the Overall Microbiological Quality of Sprouts—Two Methods of Application

Abstract

Background: the aim of this study was to improve the overall microbiological quality of five different sprouts (alfalfa, kale, lentil, sunflower, radish) using newly isolated bacteriophages. Method: in this study we had isolated from sewage 18 bacteriophages targeting bacteria dominant in sprouts. Five selected bacteriophage strains were photographed using a transmission electron microscope (TEM), and we analyzed the rate of attachment, resistance to chloroform, the burst size, and the latency period. Two methods of application of the phage cocktail were investigated: spraying, and an absorption pad. Results: the spraying method was significantly more efficient, and the maximum reduction effect after 48 h of incubation was 1.5 log CFU/g. Using pads soaked with phage lysate reduced the total number of bacteria to only about 0.27–0.79 log CFU/g. Conclusion: the reduction of bacteria levels in sprouts depended on the method of phage application. The blind strategy for searching phage targeting bacteria dominant in sprouts can be useful and economically beneficial as a starting point for further investigation in phage cocktail application for improving the overall microbiological quality of food. The main result of our research is to improve the overall quality of kale and radish sprouts by spraying them with a phage cocktail.

Characterization and Genome Study of Novel Lytic Bacteriophages against Prevailing Saprophytic Bacterial Microflora of Minimally Processed Plant-Based Food Products

“…In recent years, great attention has been paid to biological methods of food preservation [22,23]. Recently, there has been growing interest in the use of lytic bacteriophages as an innovative bio-preservative of fresh and minimally processed food products that can inhibit the growth of food-borne pathogens and spoilage microorganisms [22,24,25].…”

The use of bacteriophages against saprophytic mesophilic bacteria in minimally processed food [pdf]

“…There are many studies available that assess the microbiological quality of minimally processed plant products. An assessment of microbiological quality of sprouts carried out by Gientka et al (2021) showed that the most microbiologically contaminated were alfalfa sprouts (TNB = 8.14 log CFU/g). In other studies (Berthold-Pluta et al, 2017), the total count of aerobic mesophilic bacteria in samples of lettuces, sprouts and non-pasteurized fruit, vegetable and fruitvegetable juices was in the range of 5.6-7.6, 6.7-8.4 and 2.9-7.7 log CFU/g, respectively.…”

“…We found only one study in which the effect of adding a bacteriophage suspension on the level of TNB was tested. In the experiment of Gientka et al (2021), similarly to this article, various methods for applying phage suspensions were used. The spraying method was significantly more efficient on sprouts than a pad soaked with phage, and the maximum reduction effect after 48 h of incubation was 1.5 log CFU/g.…”

“…The use of bacteriophages prolongs the shelf life of the product without altering its physical properties . Bacteriophages are highly specific bacterial viruses which can usually infect only one species or one type of bacteria, and, unlike antibiotics, they do not destroy the natural commensal microbiota in the gastrointestinal tract of humans (Gientka et al, 2021). Research shows that phages are invulnerable to many stressful conditions during food processing (wide temperature range, pH).…”

“…Phages are applied in three sectors in the food industry: primary production (mainly used to prevent the formation of biofilms on the surface of equipment), bio-sanitization (mainly used in production facilities), and bio-preservation (used to extend the shelf life of products by combatting pathogenic bacteria that spoil food). In the case of minimally processed food, the reduction of product quality due to the growth of accompanying saprophytic microflora poses a significant problem (e.g., spoilage of products, rotting, deterioration of color and taste; Gientka et al, 2021).…”