AUTHOR=Schäfer Lea , Volk Frank , Kleespies Regina G. , Jehle Johannes A. , Wennmann Jörg T. 

TITLE=Elucidating the genomic history of commercially used Bacillus thuringiensis subsp. tenebrionis strain NB176

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2023.1129177

DOI=10.3389/fcimb.2023.1129177

ISSN=2235-2988

ABSTRACT=<p><italic>Bacillus thuringiensis</italic> subsp. <italic>tenebrionis</italic> (Btt) produces a coleopteran-specific crystal protoxin protein (Cry3Aa δ-endotoxin). After its discovery in 1982, the strain NB125 (DSM 5526) was eventually registered in 1990 to control the Colorado potato beetle (<italic>Leptinotarsa decemlineata</italic>). Gamma-irradiation of NB125 resulted in strain NB176-1 (DSM 5480) that exhibited higher cry3Aa production and became the active ingredient of the plant protection product Novodor<sup>®</sup> FC. Here, we report a comparative genome analysis of the parental strain NB125, its derivative NB176-1 and the current commercial production strain NB176. The entire genome sequences of the parental and derivative strains were deciphered by a hybrid <italic>de novo</italic> approach using short (Illumina) and long (Nanopore) read sequencing techniques. Genome assembly revealed a chromosome of 5.4 to 5.6 Mbp and six plasmids with a size range from 14.9 to 250.5 kbp for each strain. The major differences among the original NB125 and the derivative strains NB176-1 and NB176 were an additional copy of the <italic>cry3Aa</italic> gene, which translocated to another plasmid as well as a chromosomal deletion (~ 178 kbp) in NB176. The assembled genome sequences were further analyzed <italic>in silico</italic> for the presence of virulence and antimicrobial resistance (AMR) genes.</p>