Distribution of phenotypes among Bacillus thuringiensis strains.
An extensive collection of Bacillus thuringiensis isolates from around the world were phenotypically profiled using standard biochemical tests. Six phenotypic traits occurred in 20-86% of the isolates and were useful in distinguishing isolates: production of urease (U; 20.5% of isolates), hydrolysis of esculin (E; 32.3% of isolates), acid production from salicin (A; 37.4% of isolates), acid production from sucrose (S; 34.0% of isolates), production of phospholipase C or lecithinase (L; 79.7% of isolates), and hydrolysis of starch (T; 85.8% of isolates). With the exception of acid production from salicin and hydrolysis of esculin, which were associated, the traits assorted independently. Of the 64 possible combinations of these six phenotypic characteristics, 15 combinations accounted for ca. 80% of all isolates, with the most common phenotype being TL (23.6% of isolates). Surprisingly, while the biochemical traits generally assorted independently, certain phenotypic traits associated with the parasporal crystal were correlated with certain combinations of biochemical traits. Crystals that remained attached to spores (which tended to be non-toxic to insects) were highly correlated with the phenotypes that included both L and S. Among the 15 most abundant phenotypes characterizing B. thuringiensis strains, amorphous crystals were associated with TLE, TL, T, and Ø (the absence of positive tested biochemical traits). Amorphous crystal types displayed a distinct bias toward toxicity to dipteran insects. Although all common phenotypes included B. thuringiensis isolates producing bipyramidal crystals toxic to lepidopteran insects, those with the highest abundance of these toxic crystals displayed phenotypes TLU, TLUA, TLUAE, and TLAE.
Martin
Phyllis A W
PA
USDA/ARS Invasive Insect Biocontrol and Behavior Laboratory, Beltsville, MD 20705, USA. Phyllis.martin@ars.usda.gov <Phyllis.martin@ars.usda.gov>
Gundersen-Rindal
Dawn E
DE
Blackburn
Michael B
MB
D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry / Q000145:classification* / Q000201:enzymology / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D015373:Bacterial Typing Techniques; D001592:Benzyl Alcohols / Q000378:metabolism; D004175:Diptera / Q000187:drug effects; D004731:Endotoxins / Q000096:biosynthesis / Q000737:chemistry / Q000633:toxicity; D004929:Esculin / Q000378:metabolism; D005960:Glucosides; D006460:Hemolysin Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000633:toxicity; D007915:Lepidoptera / Q000187:drug effects; D010641:Phenotype; D010740:Phospholipases / Q000378:metabolism; D013171:Spores, Bacterial / Q000737:chemistry; D013213:Starch / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism; D014510:Urease / Q000378:metabolism
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001592:Benzyl Alcohols; D004731:Endotoxins; D005960:Glucosides; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D004929:Esculin; C005696:salicin; D013395:Sucrose; D013213:Starch; D010740:Phospholipases; D010738:Type C Phospholipases; D014510:Urease