• Comparative genomics of lactic acid bacteria reveals a niche-specific gene set

      O'Sullivan, Orla; O'Callaghan, John; Sangrador-Vegas, Amaia; McAuliffe, Olivia; Slattery, Lydia; Kaleta, Pawel; Callanan, Michael J.; Fitzgerald, Gerald F; Ross, R Paul; Beresford, Tom (Biomed Central, 05/03/2009)
      Background: The recently sequenced genome of Lactobacillus helveticus DPC4571 1 revealed a dairy organism with significant homology (75% of genes are homologous) to a probiotic bacteria Lb. acidophilus NCFM 2. This led us to hypothesise that a group of genes could be determined which could define an organism's niche. Results: Taking 11 fully sequenced lactic acid bacteria (LAB) as our target, (3 dairy LAB, 5 gut LAB and 3 multi-niche LAB), we demonstrated that the presence or absence of certain genes involved in sugar metabolism, the proteolytic system, and restriction modification enzymes were pivotal in suggesting the niche of a strain. We identified 9 niche specific genes, of which 6 are dairy specific and 3 are gut specific. The dairy specific genes identified in Lactobacillus helveticus DPC4571 were lhv_1161 and lhv_1171, encoding components of the proteolytic system, lhv_1031 lhv_1152, lhv_1978 and lhv_0028 encoding restriction endonuclease genes, while bile salt hydrolase genes lba_0892 and lba_1078, and the sugar metabolism gene lba_1689 from Lb. acidophilus NCFM were identified as gut specific genes. Conclusion: Comparative analysis revealed that if an organism had homologs to the dairy specific geneset, it probably came from a dairy environment, whilst if it had homologs to gut specific genes, it was highly likely to be of intestinal origin. We propose that this "barcode" of 9 genes will be a useful initial guide to researchers in the LAB field to indicate an organism's ability to occupy a specific niche.
    • The potential of non-starter lactic acid bacteria from Cheddar cheese to colonise the gut

      Leeuwendaal, N.; STANTON, CATHERINE; O'Toole, P.W.; Beresford, Tom; Teagasc Walsh Fellowship Programme; Science Foundation Ireland; JPI Food Processing for Health; 2014073 (Elsevier BV, 2021-05-27)
      This study was undertaken to assess the potential of Non-Starter Lactic Acid Bacteria (NSLAB) from Cheddar cheese to survive gastric transit and display probiotic-related traits including bile salt hydrolase activity, the ability to adhere to the gut epithelium and inhibition of enteropathogen binding. Populations of NSLAB, up to 107 CFU/g per cheese were recovered following exposure of cheese to Simulated Stomach Duodenum Passage (SSDP) conditions. A total of 240 isolates were randomly selected from twelve Cheddar cheeses and assessed for probiotic traits. Two strains Lactobacillus paracasei DPC 7150 and Lactobacillus rhamnosus DPC 7102 showed the most probiotic potential. The Lb. paracasei and Lb. rhamnosus strains displayed adhesion rates of 64% and 79%, respectively and inhibited binding of pathogenic Escherichia coli by >20%. This research demonstrates that Cheddar cheese harbours potentially beneficial bacteria, a large portion of which can survive simulated digestion and potentially exhibit health beneficial effects once ingested.
    • The Prevalence and Control of Bacillus and Related Spore-Forming Bacteria in the Dairy Industry

      Gopal, Nidhi; Hill, Colin; Ross, R Paul; Beresford, Tom; Fenelon, Mark; Cotter, Paul D.; Teagasc Walsh Fellowship Programme; Irish Dairy Levy Research Trust (Frontiers Media S. A., 21/12/2015)
      Milk produced in udder cells is sterile but due to its high nutrient content, it can be a good growth substrate for contaminating bacteria. The quality of milk is monitored via somatic cell counts and total bacterial counts, with prescribed regulatory limits to ensure quality and safety. Bacterial contaminants can cause disease, or spoilage of milk and its secondary products. Aerobic spore-forming bacteria, such as those from the genera Sporosarcina, Paenisporosarcina, Brevibacillus, Paenibacillus, Geobacillus and Bacillus, are a particular concern in this regard as they are able to survive industrial pasteurization and form biofilms within pipes and stainless steel equipment. These single or multiple-species biofilms become a reservoir of spoilage microorganisms and a cycle of contamination can be initiated. Indeed, previous studies have highlighted that these microorganisms are highly prevalent in dead ends, corners, cracks, crevices, gaskets, valves and the joints of stainless steel equipment used in the dairy manufacturing plants. Hence, adequate monitoring and control measures are essential to prevent spoilage and ensure consumer safety. Common controlling approaches include specific cleaning-in-place processes, chemical and biological biocides and other novel methods. In this review, we highlight the problems caused by these microorganisms, and discuss issues relating to their prevalence, monitoring thereof and control with respect to the dairy industry.