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J Appl Microbiol. 2014 Sep;117(3):654-62. doi: 10.1111/jam.12560. Epub 2014 Jun 30.

Bacillus thuringiensis HD-1 Cry- : development of a safe, non-insecticidal simulant for Bacillus anthracis.

Author information

1
Detection Department, Defence Science and Technology Laboratory, Salisbury, Wiltshire, UK.

Abstract

AIMS:

A representative simulant for spores of Bacillus anthracis is needed for field testing. Bacillus thuringiensis is gaining recognition as a suitable organism. A strain that does not form the insecticidal, parasporal crystals that are characteristic of this species is a more accurate physical representative of B. anthracis spores. We developed noninsecticidal derivatives of two isolates of B. thuringiensis HD-1.

METHODS AND RESULTS:

Two plasmid-cured derivatives of B. thuringiensis HD-1, unable to make crystal toxins ('Cry(-) '), were isolated. These isolates and the existing Cry(-) strain, B. thuringiensis Al Hakam, were probed with PCR assays against the known insecticidal genes cry, vip and cyt. Their genomic DNA was sequenced to demonstrate a lack of insecticidal genes. This was confirmed by bioassays against a number of invertebrate species. Real-time PCR assays were developed to identify the B. thuringiensis HD-1 Cry(-) derivatives and an effective differential and selective medium was assessed.

CONCLUSIONS:

All three Cry(-) isolates are devoid of known insecticidal determinants. The B. thuringiensis HD-1 Cry(-) derivatives can easily be recovered from soil and identified by PCR with some selectivity.

SIGNIFICANCE AND IMPACT OF THE STUDY:

The B. thuringiensis HD-1 Cry(-) derivatives represent accurate, nongenetically manipulated simulants for B. anthracis with excellent human and environmental safety records.

KEYWORDS:

Bacillus anthracis; Bacillus thuringiensis; noninsecticidal; safety; simulant; spore

PMID:
24903218
DOI:
10.1111/jam.12560
[Indexed for MEDLINE]
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