Functional Properties (Acid and Bile Tolerance) and Antibiotic Susceptibility of Lactic Acid Bacteria Isolated from Newborn Calves for the Design of a Probiotic Product

Abstract

Diarrhea in young calves in dairy farms is one of the main causes of economic losses, morbidity and mortality. The use of probiotic products as feed additives or complements is a novel alternative for the prevention of intestinal syndromes. In order to include beneficial bacteria in the design of a probiotic product, their functional and safety characteristics must be studied. The aim of this work is to evaluate the behavior of the strains in some "in vitro" gastrointestinal conditions such as acid stress and bile salts in the specific physiological concentration of young calves. The antibiotic susceptibility of a group of lactic acid bacteria from calves which were identified due to their beneficial properties was also studied. The strains, genetically identified and used for the resistance assays were: Lactobacillus johnsonii CRL1692, CRL1693, CRL1699, CRL1700, CRL1701 and CRL1706; L. amylovorus CRL1697; L. murinus CRL 1695 and CRL1705; L. mucosae CRL1696 and CRL1698; L. salivarius CRL1694 and CRL1702; and Enterococcus faecium CRL1703. The results of gut resistance assays showed that all the strains were resistant to pH 4 and to a bile salts concentration of less than 0.5%. However, some of them were sensitive to pH 2. The most pH-sensitive strains were found to be L. johnsonii and L. amylovorus, and enterococci. However, pre-treatment at low pH increased the growth rate of the L. salivarius strains. The minimal inhibitory concentration showed that the strains were sensitive to Tetracycline, Erythromycin, Chloramphenicol and Ampicillin, while most of them were resistant to Kanamycin. The results allowed the selection of the most adequate strains to be included in a probiotic product that can be utilized most successfully in young calves.product on which we are working is directed to newborn calves, recognized as non-ruminant up to the time when the rumen becomes functional, which means that the digestive process is developed in a different way than in young animals. In calves, gastric juices are secreted daily by the stomach, resulting in the destruction of most of the microorganisms ingested with the food. Then, resistance to the acid conditions of the stomach is one of the selection criteria applied in the selection of probiotic bacteria [11].

Characterization and anti-salmonella activities of lactic acid bacteria isolated from cattle faeces

“…Lactobacilli are known to exhibit a wide range of antibiotic resistance naturally, which are not transmissible and do not form a safety concern [ 51 ]. The result of our antimicrobial susceptibility testing is corroborated with the report of Maldonado and Nader-Macías [ 52 ] where the entire LAB isolated from calves faeces were all susceptible to erythromycin, ampicillin and chloramphenicol and all but one isolate was resistant to the aminoglycoside kanamycin. Intrinsic resistance to aminoglycoside antibiotics in Lactobacillus spp has been reported by several authors [ 53 – 57 ].…”

Effect of Milk Fermented with Lactic Acid Bacteria on Diarrheal Incidence, Growth Performance and Microbiological and Blood Profiles of Newborn Dairy Calves

“…Nutritional parameters, microorganisms in feces and blood parameters on calves were assessed as well. The strains used were previously isolated from calves from the northwestern region of Argentina and selected on the basis of their beneficial, functional, compatible and safety characteristics [16,17]. Technological studies such as the production of the fermented milk and the resistance of LAB to dairy farm conditions were also conducted [19] .…”

Bacillus strains from the ovaries of Swiss albino mice (Mus musculus): deciphering of probiotic potential through an in vitro approach

“…In vitro experiments have shown that spores of various strains of Bacillus have the ability to survive under simulated gastrointestinal conditions such as acidic pH and bile salts (19). Previous research revealed that Lactic acid bacteria isolated from neonatal calves had strain-specific tolerance to bile salt and acidic pH (20). At a pH of -2.5, the OM03 and OM02 strains displayed a maximum survival percentage of 57.34 ±5.10 and 55±2.89, respectively, and a colony-forming unit count of 13 x 10 8 and 11 x 10 8 , respectively.…”

“…A good probiotic should preferably be nontoxic, and free of vectors capable of spreading antibiotic resistance as well as pathogenicity or toxicity factors (20). Except for OM02 and OM04, all other strains were found to be non-β-haemolytic, and making them suitable for usage as probiotics.…”