Bio-Based Antimicrobial Agents to Improve Agricultural and Food Safety

Surfactin is a biosurfactant of the lipopeptide-type that has excellent physicochemical properties and biological activity. However, surfactin’s high cost and low productivity of the wild strains restrict its large-scale manufacturing and application. Hence, numerous engineered bacteria have been utilized to boost surfactin biosynthesis. The current review includes information on the structure, physicochemical properties, and antibacterial mechanism of surfactin. This article also summarizes the regulatory network of surfactin biosynthesis, the molecular modification strategies, and the major function of surfactin, as well as its applications in agriculture, livestock, aquaculture and the food field. Finally, future prospects for surfactin research are discussed.

Fungi and mycotoxin contamination is one of the major concerns in agriculture as well as the food system, therefore, searching for environmentally friendly and efficient biogenic fungicides has become the path to ensure food safety. Bacillomycin is a new type of cyclic lipopeptide biogenic fungicide secreted by Bacillus sp. It not only has a strong antifungal function but also has the characteristics of green safety, high stability, and drug resistance. This chapter describes the structural types, biosynthesis and regulation, and culture optimization of bacillomycin in detail and introduces its applications in the protection of plant diseases and green preservation of fruits, vegetables, aquatic products, and cereal products.

Fengycin is a cyclic lipopeptide produced mainly by the Bacillus genus, which is structurally composed of a β-hydroxy fatty acid and 10 amino acids. The biosynthesis of fengycin is catalyzed by large non-ribosomal peptide synthetases. Fengycin is an amphiphilic molecule with strong surface activity and displays strong antimicrobial activity. In this chapter, the molecular structure and biological properties of fengycin, and the function and catalyzing mechanism of fengycin multienzyme were summarized. Multiple antimicrobial mechanisms of fengycin and the strategies for increasing the production of fengycin were introduced. Fengycin has the advantages of low toxicity, biodegradation and high stability. Its applications, including biological control of plant pathogens, bioremediation of a contaminated environment, postharvest disease control of fruit and vegetables, food processing and preservation, etc., were reviewed finally.

The bacterium Brevibacillus laterosporus, which forms spores, is found in various environments, including soil, water, plants, and food. Parasporal crystals of B. laterosporus are well known for their insecticidal properties against a wide range of invertebrate pests. In the chapter, the isolation and identification of various antimicrobials produced by B. laterosporus, such as lacterosporamine (C17H35N7O4), Basiliskamide A and Basiliskamide B, Tostadin, Gramicidin A-C, Gramididin S, Tyrocidine A-C, laterocidin, and Loloatin A-D, and the linear lipopeptides Bogorol AE, Brevibacillin were reviewed. Furthermore, their antimicrobial mechanism, biosynthesis, and potential applications in food and agriculture were introduced.

Bacteriocins are ribosomally-synthesized peptides or proteins with broad or narrow-spectrum antimicrobial activity. Bacteriocins produced by lactic acid bacteria (LAB) are considered natural preservatives with safe and green properties, and their use in food preservation meets consumer demand. In this paper, the classification of LAB bacteriocins and their antimicrobial mechanisms are described in detail. Its application in the preservation of food products such as meat, dairy, seafood, fruits and vegetables is reviewed. The application of bacteriocins in hurdle technology is also presented, including their combination with other antimicrobial agents such as essential oils, bacteriophages, lysozymes, chemical antimicrobial agents, as well as thermal and non-thermal processing technology. To sum up, this review will provide insights for researchers working with lactobacillus bacteriocins as well as for industry personnel looking for new methods of natural and safe food preservation.

Each year, economic losses in the food industry due to spoilage of grain, aquatic products and fruit are huge. People now express more concern about food safety and nutrition, therefore, the need for green preservatives is also growing. Epsilon-poly-L-lysine (ε-PL), a cationic polyamino acid with 25–35 L-lysine residues, possesses broad-spectrum antimicrobial activity, biodegradable properties, resistance to high temperature, and non-toxicity and can dissolve in water. So, it has been extensively applied in the field of preservatives for foodstuffs, agriculture and biomedicine. Thus, the chapter mainly focuses on the recent research on microbial synthesis, production enhancement, and antimicrobial mechanism, as well as improving food safety, its utilization in food packaging materials and agriculture of εPL . 

The application of bacteriophages (phages) that target and kill bacteria to safeguard foods and food production facilities has attracted attention over the last decade. As phages are often already present in foods and food production settings, their specificity and antimicrobial activity against foodborne bacterial pathogens can be harnessed to affect biocontrol/bio-sanitization with minimal risk to the product or the consumer. Efficacy studies on foodborne bacterial pathogens have established the utility of the approach, and these, coupled with the inherent safety of phages, have led to regulatory approvals and the marketing of phage products for food safety. Here, we review the supporting research that demonstrates the effects of phage on foods and food contact surfaces with specific reference to the challenges of controlling bacteria that can resist conventional cleaning processes either due to adaption and/or refuge in microbial biofilms. 

Plant-based antimicrobials have been intensively studied in response to consumers’ need to reduce the use of synthetic chemical antimicrobials, as well as the global antibiotic resistance crisis. Bioactive compounds extracted from plants exert potential antimicrobial activities. In this chapter, recent research on their antimicrobial activities against foodborne pathogens in planktonic or biofilm state, antimicrobial mechanisms, their applications and limitations in food were reviewed. Additionally, the delivery methods for plant-based antimicrobials, including multi-hurdle, nanoemulsions, and edible coating/film technologies, were summarized. Lastly, the future research needs on plant-based antimicrobials were discussed.