Ongoing outbreaks of foodborne diseases remain a significant public health concern. Lytic phages provide promising attributes as biocontrol agents. This study characterized KFS-EC3, a polyvalent and lytic phage, which was isolated from slaughterhouse sewage and purified by cesium chloride density centrifugation. Host range and efficiency of plating analyses revealed that KFS-EC3 is polyvalent and can efficiently infect E. coli O157:H7, Salmonella spp., and Shigella sonnei. KFS-EC3 had a latent time of 20 min and burst size of ~71 phages/infected cell. KFS-EC3 was stable and infectious following storage at a pH range of 3 to 11 and a temperature range of −70 °C to 60 °C. KFS-EC3 could inhibit E. coli O157:H7 growth by 2 logs up to 52 h even at the lowest MOI of 0.001. Genomic analysis of KFS-EC3 revealed that it consisted of 167,440 bp and 273 ORFs identified as functional genes, without any genes associated with antibiotic resistance, virulence, allergenicity, and lysogenicity. This phage was finally classified into the Tequatrovirus genus of the Myoviridae family. In conclusion, KFS-EC3 could simultaneously infect E. coli O157:H7, S. sonnei, and Salmonella spp. with the lowest MOI values over long periods, suggesting its suitability for simultaneous pathogen control in foods.

The present study aimed to evaluate the safety of Bacillus subtilis (BS) IDCC1101, newly isolated from Cheonggukjang in Korea. Genome sequencing of BS IDCC1101 was performed to investigate the presence of secondary metabolites, virulence, antibiotic resistance, and mobile elements. Its phenotypic safety analyses included antibiotic susceptibility, enzyme activity, carbohydrate utilization, production of biogenic amines (BAs) and D-/L-lactate, hemolytic activity, and toxicities in HaCaT cells and rats. The genome of BS IDCC1101 consisted of 4,118,950 bp with 3077 functional genes. Among them, antimicrobial and antifungal secondary metabolites were found, such as fengycin, bacillibactin, and bacilysin. Antibiotic resistance and virulence genes did not exhibit transferability since they did not overlap with mobile elements in the genome. BS IDCC1101 was susceptible to almost all antibiotics suggested for assessment of BS’s antibiotic susceptibility by EFSA guidelines, except for streptomycin. BS IDCC1101 showed the utilization of a wide range of 27 carbohydrates, as well as enzyme activities such as alkaline phosphatase, esterase, esterase lipase, naphthol-AS-BI-phosphohydrolase, α-galactosidase, β-galactosidase, α-glucosidase, and β-glucosidase activities. Additionally, BS IDCC1101 did not exhibit the production of D-/L-lactate and hemolytic activities. Its toxicity in HaCaT cells and rats was also not detected. Thus, these genotypic and phenotypic findings indicate that BS IDCC1101 can be safely used for industrial applications.

This study aimed to isolate lactic acid bacteria (LAB) from a traditional Ethiopian fermented product, Tella, and evaluate their functional properties. Of forty-three isolates, seven LAB were screened and identified as Pediococcus pentosaceus, Latilactobacillus curvatus, Leuconostoc mesenteroides, and Lactiplantibacillus plantarum species. The isolates were tested for their alcohol tolerance, acid and bile resistance, auto-aggregation, co-aggregation, hydrophobicity, antibacterial activity, and antibiotic susceptibility. LAB isolates, specifically P. pentosaceus TAA01, L. mesenteroides TDB22, and L. plantarum TDM41, showed a higher degree of alcohol tolerance in 8% and 10% (w/v) ethanol concentrations. Additionally, these three isolates displayed survival rates >85% in both acidic pH and bile environments. Among the isolates, L. plantarum TDM41 demonstrated the highest auto-aggregation, co-aggregation, and hydrophobicity with (44.9 ± 1.7)%, (41.4 ± 0.2)%, and (52.1 ± 0.1)% values, respectively. The cell-free supernatant of the isolates exhibited antibacterial activity against foodborne pathogens of Escherichia coli, Salmonella Enteritidis, and Staphylococcus aureus. Each isolate exhibited various levels of resistance and susceptibility to seven antibiotics and resistance was observed against four of the antibiotics tested. After performing a principal component analysis, Pediococcus pentosaceus TAA01, L. mesenteroides TDB22, and L. plantarum TDM41 were selected as the most promising ethanol-tolerant probiotic isolates.

Velvet antlers (VA) sourced from red (Cervus elaphus), sika (C. nippon), and elk (C. canadensis) deer have become increasingly popular in Chinese, Korean and Japanese traditional and oriental medicines as supplements for disease prevention. Therefore, this study aimed to determine the chemical components (proximate composition, amino, uronic, and sialic acids) and to characterize the bacterial profile of VA extract. The yield and contents of uronic and sialic acids extracted from VA at 98-100°C for 29-36 sec were determined to be 40.71%, 28.06 mg/g and 0.73 mg/g, respectively. Overall, proximate parameters were higher in extracts recovered at 100°C compared with 90°C, and these parameters were: moisture (4.66%), crude protein (86.63%), crude fat (3.23%), crude ash (4.1%), and carbohydrate content (5.43%). Alanine was the most abundant among the identified amino acids. Analysis of 16S rRNA sequence identified 12 bacterial species, including seven gram-positive and five gram-negative bacteria. Among all bacteria, Chryseobacterium indologenes, Shigella flexneri ATCC 29903, Staphylococcus equorum, Staphylococcus xylosus, Staphylococcus succinus, and Vagococcus fluvialis had 100% identity in the VA extract. The morphology of C. indologene, S. flexneri ATCC 29903, and V. fluvialis was bacilli, whereas S. equorum, S. succinus, and S. xylosus were cocci.

The purpose of this study was to characterize lytic and genomic properties of phage KFS-EC3 used as a biocontrol agent. The morphology of KFS-EC was observed by transmission electron microscopy (TEM). The polyvalent bactericidal activity of KFS-EC3 was determined against various host bacteria by enumerating bacterial number after phage treatment at multiplicities of infection (MOIs) of 0.001, 0.1, and 1.0 for 4 h. Finally, whole-genome sequencing was performed and annotated to identify its lytic property, safety, and novelty. TEM observation revealed that KFS-EC had morphology of myophage with an icosahedral head and contractile tail. In addition, KFS-EC3 could reduce E. coli, The Salmonella, Shigella sonnei, and their bacterial cocktail by ∼3 log CFU/mL, even at the lowest MOI of 0.001. The genomic analyses revealed that KFS-EC3 consisted of 167,440 bp and 151 functional genes, without any genes related to antibiotic resistance, virulence, allergenicity, and lysogenicity. Among the genes involved in host cell lysis, endolysin, holin, and a receptor binding protein were identified. Furthermore, KFS-EC3 was classified into a new phage of the Tequatrovirus genus in the Myoviridae family. In conclusion, lytic and safe phage KFS-EC3 with a broad host range can be used as a biocontrol agent to control foodborne pathogens.

This study aimed to characterize a lytic Salmonella Typhimurium-specific (ST) phage and its biofilm control capability against S. Typhimurium biofilm on polypropylene surface. ST phage was isolated, propagated, and purified from water used in a slaughterhouse. The morphology of ST phage was observed via transmission electron microscopy. Its bactericidal effect was evaluated by determining bacterial concentrations after the phage treatment at various multiplicities of infection (MOIs) of 0.01, 1.0, and 100. Once the biofilm was formed on the polypropylene tube after incubation at 37°C for 48 h, the phage was treated and its antibiofilm capability was determined using crystal violet staining and plate count method. The phage was isolated and purified at a final concentration of ∼11 log PFU/mL. It was identified as a myophage with an icosahedral head (∼104 nm) and contractile tail (∼90-115 nm). ST phage could significantly decrease S. Typhimurium population by ∼2.8 log CFU/mL at an MOI of 100. After incubation for 48 h, biofilm formation on polypropylene surface was confirmed with a bacterial population of ∼6.9 log CFU/cm2. After 1 h treatment with ST phage, the bacterial population in the biofilm was reduced by 2.8 log CFU/cm2. Therefore, these results suggest that lytic ST phage as a promising biofilm control agent for eradicating S. Typhimurium biofilm formed on food contact surfaces.