Comparison of in vitro and in situ antagonism assays as tools for the selection of bio-preservative lactic acid bacteria (LAB) in poultry meat

Effects of quercetin- and Lactiplantibacillus plantarum-containing bioactive films on physicochemical properties and microbial safety of grass carp

In this study, the electrospinning technique was used to co-encapsulate Quercetin (Qu) and Lactiplantibacillus plantarum 1-24-LJ in PVA-based nanofibers, and the effect of bioactive films on fish preservation was evaluated at the first time. The findings indicated that both Lpb. plantarum 1-24-LJ and Qu were successfully in the fibers, and co-loaded fibers considerably outperformed single-loaded fiber in terms of bacterial survival and antioxidant activity. Following fish preservation using the loaded fibers, significant reductions were observed in TVB-N, TBARS, and microbial complexity compared to the control group. Additionally, the co-loaded fibers more effectively reduced the counts of H2S-producing bacteria and Pseudomonas. In the future, fibers with both active substances and LAB hold promise as a novel approach for fish preservation.

Antagonist action of Lactobacillus acidophilus against pathogenic strains in goat milk yogurt

Contamination by pathogenic bacteria is the major cause of foodborne diseases, which is an international public health issue. Probiotics added to fermented milk can fight against these pathogens. This research aimed to evaluate, by mathematical models, the behaviour of Lactobacillus acidophilus against pathogenic strains inoculated in goat milk yogurt. The Baranyi and Roberts' model was adjusted to data and statistically evaluated. A greater pathogens reduction occurred in the samples supplemented with probiotics, which exhibited antimicrobial activity against Pseudomonas aeruginosa. The reduction was less efficient against Escherichia coli. The primary models adjustment indicated that the Baranyi and Roberts fitted the reduction of P. aeruginosa, Salmonella typhimurium, E. coli and Staphylococcus aureus inactivation. The addition of L. acidophilus proved to be an effective alternative for the safer production of goat milk yogurt.

The biological effect of a beef-derived Latilactobacillus sakei on beef steaks during chilled storage

The aim of this study was to investigate the biological inhibiting effect of a beef-derived Latilactobacillus sakei (RS-25) on the spoilage of beef steaks in overwrapped packaging during the 12 days of storage at 4°C. Beef quality as well as microbial indicators were determined at different intervals during the storage after the inoculation of RS-25 at the 6 log CFU/g, and the high-throughput sequencing was applied to investigate the changes of microbial community structure during the storage. The inoculation of RS-25 on beef had no effect (p > .05) on pH, TBARS, and TVB-N during storage indicating the weak effect of such strain on the eat quality. Furthermore, the rise of L* and the delayed decline of a* and b* reveal the protection effect of RS-25 on the meat color. RS-25 reduced the re-contaminated Salmonella typhimurium by 1.16 log CFU/g (p < .01), and the growth of Brochothrix thermosphacta was also inhibited but no inhibition was found on the Pseudomonas spp. at the first 6 days of storage. The inhibiting effect of RS-25 was covered by the rapid growth of other microorganism during the following 6 days of storage. Consistent with the microbial counts results, high-throughput sequencing analysis confirmed that the inoculated L. sakei RS-25 was dominant at first 6 days, and then replaced by Pseudomonas spp. The findings obtained from the current study may provide basic information for the further application of bioprotective bacteria in preservation of beef steaks in the overwrapped packaging.

Active Biopolymeric Films Inoculated with Bdellovibrio bacteriovorus, a Predatory Bacterium

The objective of the present work was to evaluate novel active films made with biopolymeric matrices as carriers of a living Bdellovibrio bacteriovorus HD100 strain, a predatory bacterium with antimicrobial potentials against pathogens. Biopolymer films were prepared by a casting method using the following mixtures: collagen/sodium alginate/sorbitol (CA-S), collagen/sodium alginate/glycerol (CA-G), and tapioca starch/sodium alginate/glycerol (StA-G). The effects of the film formulations on the viability of the B. bacteriovorus was investigated by using Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM). SEM showed that Bdellovibrio bacteriovorus morphology was not altered in the polymeric films. FTIR spectroscopy provided information about the structural composition of the films. CA-S showed less reduction in the viability of B. bacteriovorus after its entrapment; thus, CA-S proved to be a better agent for the immobilization and preservation of B. bacteriovorus to enhance its predatory activities during application against Escherichia coli.