ABSTRACT
AIMS: Lactic acid bacteria (LAB) were isolated and sequenced from the faeces of healthy dogs. Five of these strains were selected and further characterized to clarify the potential of these strains as probiotics for canine. METHODS AND RESULTS: LAB were found in 67% (14/21) of the canine faeces samples when plated on Lactobacilli Selective Media without acetic acid. Out of 13 species identified with partial 16S rRNA gene sequencing, Lactobacillus fermentum LAB8, L. mucosae LAB12, L. rhamnosus LAB11, L. salivarius LAB9 and Weissella confusa LAB10 were selected as candidate probiotic strains based on their frequency, quantity in faeces, growth density, acid tolerance and antimicrobial activity. The minimal inhibitory concentration values of these isolates were determined for 14 antibiotics. L. salivarius LAB9, W. confusa LAB10 and L. mucosae LAB12 were viable in pH 2 for 4 h (mLBS), indicating tolerance to acidity and thus the potential to survive in gastrointestinal tract of the canine. The LAB8-LAB12 strains showed antimicrobial activity against Micrococcus luteus A1 NCIMB86166. CONCLUSIONS: Thirteen different LAB species were found from the faecal microbiota of the healthy canines. Five acid tolerant and antimicrobially active LAB strains with the capacity to grow to high densities both aerobically and anaerobically were chosen to serve as candidate probiotics. SIGNIFICANCE AND IMPACT OF THE STUDY: The selected LAB strains are among the first host-specific LAB with antimicrobial activity isolated from canines that could serve as potential probiotics for canine use.
Subject(s)
Dogs/microbiology , Feces/microbiology , Lactobacillus/isolation & purification , Probiotics/isolation & purification , Animals , Anti-Bacterial Agents/pharmacology , Antibiosis , Bacteriological Techniques , Hydrogen-Ion Concentration , Lactobacillus/genetics , Microbial Sensitivity Tests , Probiotics/pharmacology , RibotypingABSTRACT
Lactic acid bacteria originating in the intestine have recently undergone intensive study for their potential probiotic properties. Here partial 16S rRNA gene sequencing of 8 Lactobacillus strains proved them to be Lactobacillus crispatus. Fatty acid analysis confirmed strains being closely related. These strains and type strain ATCC33820 were characterized for genetic engineering potential, thus determining aerobic growth, erythromycin sensitivity, and glycine tolerance. Out of 5 plasmids, a 2.9-kb plasmid (pLEB579) was successfully introduced into 4 chicken-originated wild-type L. crispatus strains. Transformation frequency was approximately 30 transformants per microgram of DNA, the first reported electrotransformation into chicken-originated L. crispatus. In spite of its low frequency, transformation enables bioengineering of these strains to improve the probiotic function in feed adsorption, chicken health, and food safety.
