Bacterial pathogen detection by conventional culture-based and recent alternative (polymerase chain reaction, isothermal amplification, enzyme linked immunosorbent assay, bacteriophage amplification, and gold nanoparticle aggregation) methods in food samples: A review
JOURNAL OF FOOD SAFETY
Authors: Kim, Sang-Oh; Kim, Sang-Soon
Abstract
The rapid, sensitive, and selective detection of foodborne pathogens is important to ensure food safety. Culture medium-based methods for bacteria detection have long been used since Robert Koch's first finding. These methods are simple and cheap but have limitations, such as being time-consuming, labor-intensive, and having low selectivity. In this regard, several alternative detection methods have been reported. Among these, recent studies related to the application of polymerase chain reaction, isothermal amplification, bacteriophage amplification, enzyme-linked immunosorbent assay, and gold nanoparticle aggregation for detection of pathogens in food are discussed in this review. The principles, advantages, and disadvantages of alternative methods are covered, including their rapidity, sensitivity, and selectivity. Finally, regulations related to bacterial pathogen detection in the United States and South Korea were compared with remarks for their progress.
Antimicrobial Activity of an Extract of Hermetia illucens Larvae Immunized with Lactobacillus casei against Salmonella Species
INSECTS
Authors: Lee, Kyu-Shik; Yun, Eun-Young; Goo, Tae-Won
Abstract
Simple Summary In this investigation, we found antimicrobial activity of the extract of Lactobacillus casei-infected Hermetia illucens larvae (HIL) against Salmonella species. The result demonstrates that the extract is a powerful natural antibiotic and preservative. The expressions of antimicrobial peptides (AMPs) in the larvae of the black soldier fly, Hermetia illucens, were significantly increased by pathogen or stimulant induced innate immunity activation. We immunized H. illucens fifth instar larvae with five different Lactobacillus species, that is, Lactobacillus acidophilus, L. brevis, L. casei, L. fermentum, or L. delbrueckii, to induce the mass production of AMPs and selected optimal immune inducers. Antimicrobial activities in hemolymph and H. illucens larvae (HIL) extract were evaluated against three salmonella species (Salmonella pullorum, Salmonella typhimurium, and Salmonella enteritidis). Highest antimicrobial activity was shown by the hemolymph of HIL immunized by L. casei and its activity was closely linked with the inductions of cecropin 1 (HiCec1) and defensin 1 (HiDef1) gene expressions. Furthermore, antimicrobial activity in hemolymph was stable to heat and pH and the growth of three Salmonella species were dramatically suppressed by HIL hemolymph and extract after immunization with L. casei. The minimal inhibitory concentration (MICs) of L. casei-immunized HIL extract against Staphylococcus aureus, Escherichia coli, and Salmonella species ranged from 100 similar to 200 mu g/100 mu L and no cytotoxicity to CaCo-2 and L929 cells were observed in the concentration range 100 similar to 40,000 mu g/100 mu L. Taken together, the present investigation demonstrates that L. casei-immunized HIL extract is a powerful natural antibiotic and preservative that can prevent contamination by Salmonella species.