Comparision of biological and genomic characteristics of five virulent bacteriophages against Enterobacter hormaechei.

Enterobacter hormaechei is a zoonotic bacteria that may cause respiratory diseases in animals and neonatal sepsis in humans. Bacteriophages are increasingly considered as potential biocontrol agents to control pathogens in the food industry. In this study, five E. hormaechei virulent phages, named as Ehp-YZU08, Ehp-YZU10, Ehp-YZU9-1, Ehp-YZU9-2 and Ehp-YZU9-3, were isolated from sewage in China and analyzed for their biological and whole-genome characteristics, and a comparative genomic analysis was performed to study the functional genes and phylogenetic evolution of phages. The results showed that four of the phage strains belong to the Podoviridae family and one belongs to the Myoviridae family. The burst sizes were 70-283 PFU/cell after a latent period of 5-40 min. Phages were able to survive in a pH range of 5-10 and resist temperatures up to 60 °C for 60 min. The sequencing results showed that the full length of the genomes of the five phages ranged from 39,502 to 173,418 bp. Each phage contained multiple genes related to phage replication, and genes related to bacterial virulence or drug resistance were not found. The five phages belonged to three different groups by a construction of a phylogenetic tree, and the significant genetic evolutionary distance from each E. hormaechei phage was observed. The inhibition assay showed that all five phages could completely inhibit the growth of E. hormaechei at 37 °C within 8 h, suggesting that the phages in this study have great potential for the development of biocontrol agents against E. hormaechei in the food industry.

Bacteriophages: A weapon against mixed-species biofilms in the food processing environment.

Mixed-species biofilms represent the most frequent actual lifestyles of microorganisms in food processing environments, and they are usually more resistant to control methods than single-species biofilms. The persistence of biofilms formed by foodborne pathogens is believed to cause serious human diseases. These challenges have encouraged researchers to search for novel, natural methods that are more effective towards mixed-species biofilms. Recently, the use of bacteriophages to control mixed-species biofilms have grown significantly in the food industry as an alternative to conventional methods. This review highlights a comprehensive introduction of mixed-species biofilms formed by foodborne pathogens and their enhanced resistance to anti-biofilm removal strategies. Additionally, several methods for controlling mixed-species biofilms briefly focused on applying bacteriophages in the food industry have also been discussed. This article concludes by suggesting that using bacteriophage, combined with other 'green' methods, could effectively control mixed-species biofilms in the food industry.

Isolation and genomic characterization of P.A-5, a novel virulent bacteriophage against Enterobacter hormaechei.

Enterobacter hormaechei is a foodborne pathogen responsible for neonatal sepsis in humans and respiratory disease in animals. In this work, a new virulent phage (P.A-5) infecting E. hormaechei was isolated from domestic sewage samples and characterized. Transmission electron microscopy revealed that P.A-5 belonged to the family Myoviridae having a head size of 77.53 nm and a tail length of 72.24 nm. The burst size was 262 PFU/cell after a latent period of 20 min. Phage P.A-5 was able to survive in a pH range of 4-9 and resist temperatures up to 55 °C for 60 min. The genome sequence of P.A-5 had homology most similar to that of Shigellae phage MK-13 (GenBank: MK509462.1). Pork artificially contaminated with E. hormaechei was used as a model to evaluate the potential of P.A-5. The results clearly showed that P.A-5 treatment can completely inhibit E. hormaechei growth in pork within 8 h, indicating the potential use of P.A-5 as a biocontrol agent for E. hormaechei.

Lactic acid bacteria biofilms and their antimicrobial potential against pathogenic microorganisms.

The continuous growth of pathogenic microorganisms and associated biofilms poses severe public health challenges, particularly in food and clinical environments. However, these difficulties have enabled scientists to develop novel and safe methods for combating pathogens. The use of biofilms produced by lactic acid bacteria (LAB) against pathogenic bacteria has recently gained popularity. This review provides an in-depth look at LAB biofilms, their distribution, and mechanisms of action against pathogenic bacteria. More importantly, the bioactive substances produced by LAB-forming biofilm may be active against undesirable microorganisms and their products, which is of great interest in improving human health. Therefore, this review implies that a combination of LAB biofilms and other LAB products like bacteriocins could provide viable alternatives to traditional methods of combating pathogenic microorganisms and their biofilms.

Characterization and comparative genomic analysis of novel lytic bacteriophages targeting Cronobacter sakazakii.

Cronobacter sakazakii, a foodborne pathogen, can contaminate powdered infant formula (PIF) and cause life-threatening meningitis, necrotizing colitis and meningoencephalitis in infants. Bacteriophages are increasingly considered an efficient approach to target pathogenic microorganisms. In the current study, four virulent phages that can infect C. sakazakii were isolated from sewage samples, and their biological and complete genomic characteristics were analyzed. A comparative genomic analysis was performed to investigate the functional genes and phylogenetic evolution of the four phages. The results revealed that all four phages belonged to the Ackermannviridae family. Notably, the viral burst size of the phages ranged from 10 to 250 PFU/cell, following a latent period of 5 min to 20 min. Moreover, phages were stable over a pH range of 4 to 10 and a temperature range of 50 ℃ to 60 ℃. The full length of the complete genomes of the four phages ranged from 41,929 bp to 146,806 bp, containing lysis genes but no virulence genes. Phylogenetic tree analysis showed that the four phages were members of two distinct genetic groups with a significant genetic evolutionary distance between each C. sakazakii phage. Furthermore, the antibacterial assay revealed that all phages could inhibit the growth of C. sakazakii for up to 24 h. Taken together, the four phages have huge prospects as additives in dairy products to counter C. sakazakii.

Characterization and valorization of soybean residue (okara) for the development of synbiotic ice cream.

There is an increasing challenge in probiotic viability and stability during food product formulation, processing, and storage. However, synbiotic functional foods have promising potential to deliver the targeted benefits. This study aimed to isolate the okara from soybean residue, and obtained okara flour was further characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Synbiotic ice cream was developed by fortification with Lactobacillus rhamnosus GG and okara at different concentrations (1-3%). Additionally, the synbiotic ice cream was subjected to physicochemical and sensory attributes over 60 days of storage. High viability of L. rhamnosus GG (8.17 log CFU/mL) was observed during storage at 3% okara. Moreover, adding okara at 2% or higher improved viscosity, reduced overrun, and maintained probiotic viability. When compared to the control (ice cream without okara), synbiotic ice cream exhibited a higher protein content and a lower fat level. The synergistic combination of probiotics and okara in ice cream is a potentially novel approach for developing functional ice cream. The addition of okara is not only helpful in increasing the nutritional value of the ice cream but will also be a way forward to minimize agricultural waste. Synbiotic ice cream developed in this study may be considered a potential functional food rich in protein and low in fat.

Understanding of food biofilms by the application of omics techniques.

Biofilms constitute a protective barrier for foodborne pathogens to survive under stressful food processing conditions. Therefore, studies into the development and control of biofilms by novel techniques are vital for the food industry. In recent years, foodomics techniques have been developed for biofilm studies, which contributed to a better understanding of biofilm behavior, physiology, composition, as well as their response to antibiofilm methods at different molecular levels including genes, RNA, proteins and metabolic metabolites. Throughout this review, the main studies where foodomics tools used to explore the mechanisms for biofilm formation, dispersal and elimination were reviewed. The data summarized from relevant studies are important to design novel and appropriate biofilm elimination methods for enhancing food safety at any point of food processing lines.