Category Archives: Lactococcus

Research – Evaluation of the safety and efficacy of lactic acid to reduce microbiological surface contamination on carcases from kangaroos, wild pigs, goats and sheep

EFSA

Studies evaluating the safety and efficacy of lactic acid to reduce microbiological surface contamination from carcases of wild game (i.e. kangaroos and wild pigs) and small stock (i.e. goats and sheep) before chilling at the slaughterhouse were assessed. Wild pig and kangaroo hide‐on carcases may have been chilled before they arrive at the slaughterhouse and are treated after removal of the hides. Lactic acid solutions (2–5%) are applied to the carcases at temperatures of up to 55°C by spraying or misting. The treatment lasts 6–7 s per carcass side. The Panel concluded that: [1] the treatment is of no safety concern, provided that the lactic acid complies with the European Union specifications for food additives; [2] based on the available evidence, it was not possible to conclude on the efficacy of spraying or misting lactic acid on kangaroo, wild pig, goats and sheep carcases; [3] treatment of the above‐mentioned carcases with lactic acid may induce reduced susceptibility to the same substance, but this can be minimised; there is currently no evidence that prior exposure of food‐borne pathogens to lactic acid leads to the occurrence of resistance levels that compromise antimicrobial therapy; and [4] the release of lactic acid is not of concern for the environment, assuming that wastewaters released by the slaughterhouses are treated on‐site, if necessary, to counter the potentially low pH caused by lactic acid, in compliance with local rules.

Research – Antagonistic Effects of Conjugated Linoleic Acids of Lactobacillus casei Against Foodborne Enterohemorrhagic Escherichia coli 

Journal of Food Protection

Probiotics in fermented foods or commercially available supplements benefit the host by providing metabolites/peptides. The production of these metabolites varies with available substrates/prebiotic present in the system and their concentration. In this study, 0.5% peanut flour (PF) was used to stimulate the growth and production of metabolites of wild-type Lactobacillus casei (LC wt ) and compare with an engineered L. casei (LC CLA ) capable of converting a higher amount of conjugated linoleic acid (CLA). The total extracellular metabolites present in the cell-free cultural supernatant (CFCS) of LC wt (without peanut), LC wt+PF (with peanut), and LC CLA were collected after 24 h and 48 h of incubation, and their antagonistic activities against enterohemorrhagic Escherichia coli (EHEC EDL933) growth and pathogenesis were evaluated. All the collected metabolites exhibited varying efficiency in restraining EDL933 growth while supplementing low concentration of CLA to the 48-h CFCS from LC wt showed augmented antagonism toward EDL933. A downregulation of key virulence genes was observed from metabolites collected at 48-h time point. These observations indicate that the presence of metabolites in CFCSs including CLA, produced by Lactobacillus , which was further identified by gas chromatography-mass spectrometry; plays a critical role. This study demonstrates the potential applicability of Lactobacillus -originated CLA in the prevention of EDL933 mediated illnesses.

Research – Lactic Acid Bacteria as Antimicrobial Agents: Food Safety and Microbial Food Spoilage Prevention

MDPI

In the wake of continual foodborne disease outbreaks in recent years, it is critical to focus on strategies that protect public health and reduce the incidence of foodborne pathogens and spoilage microorganisms. Currently, there are limitations associated with conventional microbial control methods, such as the use of chemical preservatives and heat treatments. For example, such conventional treatments adversely impact the sensorial properties of food, resulting in undesirable organoleptic characteristics. Moreover, the growing consumer advocacy for safe and healthy food products, and the resultant paradigm shift toward clean labels, have caused an increased interest in natural and effective antimicrobial alternatives. For instance, natural antimicrobial elements synthesized by lactic acid bacteria (LAB) are generally inhibitory to pathogens and significantly impede the action of food spoilage organisms. Bacteriocins and other LAB metabolites have been commercially exploited for their antimicrobial properties and used in many applications in the dairy industry to prevent the growth of undesirable microorganisms. In this review, we summarized the natural antimicrobial compounds produced by LAB, with a specific focus on the mechanisms of action and applications for microbial food spoilage prevention and disease control. In addition, we provide support in the review for our recommendation for the application of LAB as a potential alternative antimicrobial strategy for addressing the challenges posed by antibiotic resistance among pathogens. View Full-Text

Research – Characterization of bacteria and antibiotic resistance in commercially-produced cheeses sold in China

Journal of Food Protection

The consumption of cheese in China is increasing rapidly. Little is known about the microbiota, the presence of antibiotic-resistant bacteria, or the distribution of antibiotic resistance genes (ARGs) in commercially-produced cheeses sold in China. These are important criteria for evaluating quality and safety. Thus, this study assessed the metagenomics of fifteen types of cheese using 16S rRNA gene sequencing. Fourteen bacterial genera were detected. Lactococcus , Lactobacillus , and Streptococcus were dominant based on numbers of sequence reads. Multidrug-resistant lactic acid bacteria were isolated from most of the types of cheese. The isolates showed 100% and 91.7% resistance to streptomycin and sulfamethoxazole, respectively, and genes involved in acquired resistance to streptomycin ( strB) and sulfonamides ( sul2) were detected with high frequency. To analyze the distribution of ARGs in the cheeses in overall, 309 ARGs from eight categories of ARG and nine transposase genes were profiled. A total of 169 ARGs were detected in the 15 cheeses; their occurrence and abundance varied significantly between cheeses. Our study demonstrates that there is various diversity of the bacteria and ARGs in cheeses sold in China. The risks associated with multidrug resistance of dominant lactic acid bacteria are of great concern.