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Open Access Research article

Genotyping of B. licheniformis based on a novel multi-locus sequence typing (MLST) scheme

Elisabeth H Madslien12, Jaran S Olsen1, Per E Granum2 and Janet M Blatny1*

Author Affiliations

1 Forsvarets Forskningsinstitutt FFI, Norwegian Defence Research Establishment, P. O. Box 25, Kjeller, N-2027, Norway

2 Department of Food Safety and Infection Biology, Section for Food Safety, Norwegian School of Veterinary Science, P. O. Box 8146 Dep, Oslo, N-0033, Norway

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BMC Microbiology 2012, 12:230  doi:10.1186/1471-2180-12-230

Published: 10 October 2012

Abstract

Background

Bacillus licheniformis has for many years been used in the industrial production of enzymes, antibiotics and detergents. However, as a producer of dormant heat-resistant endospores B. licheniformis might contaminate semi-preserved foods. The aim of this study was to establish a robust and novel genotyping scheme for B. licheniformis in order to reveal the evolutionary history of 53 strains of this species. Furthermore, the genotyping scheme was also investigated for its use to detect food-contaminating strains.

Results

A multi-locus sequence typing (MLST) scheme, based on the sequence of six house-keeping genes (adk, ccpA, recF, rpoB, spo0A and sucC) of 53 B. licheniformis strains from different sources was established. The result of the MLST analysis supported previous findings of two different subgroups (lineages) within this species, named “A” and “B” Statistical analysis of the MLST data indicated a higher rate of recombination within group “A”. Food isolates were widely dispersed in the MLST tree and could not be distinguished from the other strains. However, the food contaminating strain B. licheniformis NVH1032, represented by a unique sequence type (ST8), was distantly related to all other strains.

Conclusions

In this study, a novel and robust genotyping scheme for B. licheniformis was established, separating the species into two subgroups. This scheme could be used for further studies of evolution and population genetics in B. licheniformis.