PCR-based screening, isolation, and partial characterization of motile lactobacilli from various animal feces

Shunya Suzuki,Shizunobu Igimi,Yuh Shiwa,Akihito Endo,Koki Fujita,Shintaro Maeno,Akinobu Kajikawa,Kenji Yokota

doi:10.1186/s12866-020-01830-7

Abstract

BackgroundMost lactobacilli found in animal intestines are generally non-motile, but there are few exceptions. Our previous work showed that Lactobacillus agilis BKN88, which is a highly motile strain originating from a chicken, takes advantage of motility in gut colonization in murine models, and thus motile lactobacilli likely have unique ecological characteristics conferred by motility. However, the ecology and habitat of gut-derived motile lactobacilli are still rarely understood. In addition, the limited availability of motile Lactobacillus isolates is one of the major obstacles for further studies. To gain insight into the ecology and habitat of the motile lactobacilli, we established a routinely applicable detection method for motile lactobacilli using PCR and subsequent selective isolation in semi-solid MRS medium for the collection of additional motile lactobacilli from animal feces.ResultsWe applied the PCR detection using motile lactobacilli-specific primers, based on the motor switch protein gene (fliG) of flagella, to 120 animal feces, followed by selective isolation performed using 45 animal feces. As a result, motile lactobacilli were detected in 44 animal feces. In the selective isolation, 29 isolates of L. agilis and 2 isolates of L. ruminis were obtained from 8 animal species.ConclusionsThese results indicated that motile lactobacilli are distributed in different animal species. Moreover, phylogenetic analysis of the L. agilis isolates suggests co-evolution with the host, and adaptation to a particular environmental niche.

Highlights

Most lactobacilli found in animal intestines are generally non-motile, but there are few exceptions
To validate the specificity of each primer pair, Polymerase chain reaction (PCR) amplification was performed with genomic DNA from eleven strains of motile lactobacilli including two strains of L. agilis and two strains of L. ruminis, and a non-motile Lactobacillus and E. coli (Table 2)
The sensitivity of each primer pair was tested by PCR amplification with DNA extracted from murine fecal pellets supplemented with serial dilutions of L. agilis BKN88 bacterial cells

Summary

Introduction

Most lactobacilli found in animal intestines are generally non-motile, but there are few exceptions. The ecology and habitat of gut-derived motile lactobacilli are still rarely understood. The limited availability of motile Lactobacillus isolates is one of the major obstacles for further studies. To gain insight into the ecology and habitat of the motile lactobacilli, we established a routinely applicable detection method for motile lactobacilli using PCR and subsequent selective isolation in semisolid MRS medium for the collection of additional motile lactobacilli from animal feces. Motility is a minor characteristic in the genus Lactobacillus, and only the small part of the species. Suzuki et al BMC Microbiology (2020) 20:142 belonging to the phylogenetic group of L. salivarius possesses motility with an exception of the specific species Lactobacillus curvatus [7]. The motilityrelated genes are usually located in single operon, which appears to be conserved [7]

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Discussion

Conclusion