Summary

There are many applications of Lactobacillus in the agricultural industry, from improving animal health, to increasing the quality of the food on our plates. Due to the vast variety of species of Lactobacillus, identifying production strains for animal feed or for human probiotics can be a long and complex process. Colony pickers can be a useful way to speed up screening assays and identify antimicrobial properties such as through measuring zones of inhibition.

What is Lactobacillus?

Lactobacillus is commonly present in probiotics, providing beneficial effects for humans and animals. The Lactobacillus genera contain Lactobacillus bulgaricus, rhamnosus, sakei and at least 258 other species [1]. Using Lactobacillus in agriculture has gained worldwide attention over the last decade due to its potential in increasing the welfare of animals and improving productivity in food production. Applications of lactobacilli include pre-harvest in animal welfare; and post-harvest and processing procedures to increase food safety and reduce the risk of contaminants before consumption.


Lactobacillus in agriculture

Lactobacilli in probiotics reduces pathogenic organisms entering the food chain, especially in emerging nations where there is distrust in the safety of the food produced [2].

In poultry, Lactobacillus strains have been identified to inhibit salmonella colonisation reducing risk of spreading infection and also reducing risk to the end consumer [3].

In research, colony pickers can be used to pick and identify production strains, PIXL has previously been used to identify strains of lactobacilli picked from MRS agar, to then be cultured in bioreactors to be supplied as probiotics for chickens.


Focus on probiotics

Probiotics containing lactobacilli have an antimicrobial effect on E.coli. Lactobacillus rhamnosus has been shown to be effective in reducing pathogenic E.coli when given to mice in fermented milk [4]. L. rhamnosus also increases production of cytokines, working as an immunostimulatory agent [5]. PIXL can be used to screen strains, such as for their ability to produce cytokines in co-culture for livestock feed, to improve the immune systems of production animals such as dairy cattle.

Interestingly, feeding cattle directly with lactobacilli containing probiotics has no significant effect on methane production [6] however as a natural modifier in alfalfa silage, combined with gallnut tannin, it improves silage quality and modulates ruminal microbiota mitigating methane production [7].


Lactobacillus in food production

Post-harvest uses of Lactobacillus include spoilage prevention, improvement of storage stability and safety and enhancement of taste [8].

The antimicrobial properties of lactobacilli have many uses, such as in cheese spread to reduce listeria monocytogenes [9]. When tested in vivo the antimicrobial properties of lactobacilli produce zones of inhibition on agar plates.

Foods that contain lactobacilli, such as milk and yogurt, provide a huge health benefit to us. Lactobacilli in probiotics for humans can influence the immune response by modulating inflammatory mediators, and this can be used to make precision probiotics for therapeutic uses.

Lactobacillus increases CD40 and CD80 expression to inhibit tumour growth and increase caspase 1 to increase cleavage of IL-1B and IL-18 into their active form to stimulate the innate immune system. Lactobacillus can also increase Treg cell number for the prevention of autoimmune diseases [10].


Explore how PIXL can accelerate your screening workflows

colony pick with the standard PIXL set up

PIXL

Is for users looking to automate manual colony picking with an intuitive and user-friendly robot.

PIXL in Anerobic Chamber with automated setup

PIXL with Anaerobic Chamber

A customised anaerobic chamber designed for PIXL with user experience in mind, making integration seamless.


References

[1] Zheng et al, (2020) A taxonomic note on the genus lactobacillus: Description of 23 novel genera, emended description of the genus lactobacillus beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae, International journal of systematic and evolutionary microbiology.

[2] Miranda, C. et al. (2021) Role of exposure to lactic acid bacteria from foods of animal origin in human health, MDPI.

[3] Hai, D. et al. (2021) In vitro screening of chicken-derived lactobacillus strains that effectively inhibit salmonella colonization and adhesion, MDPI.

[4] Sharma, R. et al. (2014) Improvement in th1/th2 immune homeostasis, antioxidative status and resistance to pathogenic E. coli on consumption of probiotic lactobacillus rhamnosus fermented milk in aging mice – Geroscience, SpringerLink.

[5] Cross, M.L. et al. (2002) Dietary intake of lactobacillus rhamnosus HN001 enhances production of both th1 and th2 cytokines in antigen-primed mice – Medical Microbiology and Immunology, SpringerLink.

[6] Jeyanathan, J. et al. (2019) Bacterial direct-fed microbials fail to reduce methane emissions in primiparous lactating dairy cows – journal of animal science and biotechnology, SpringerLink.

[7] Chen et al, (2022) Evaluation of gallnut tannin and Lactobacillus plantarum as natural modifiers for alfalfa silage: Ensiling characteristics, in vitro ruminal methane production, fermentation profile and microbiota. Applied microbiology.

[8] Miranda, C. et al. (2021) Role of exposure to lactic acid bacteria from foods of animal origin in human health, MDPI.

[9] Martinez, R et al. (2015) Bacteriocin production and inhibition of listeria monocytogenes by lactobacillus sakei subsp. sakei 2a in a potentially synbiotic cheese spread, Food Microbiology.

[10] Mazziotta, C. et al. (2023) Probiotics mechanism of action on immune cells and beneficial effects on human health, MDPI.