Paenibacillus

Paenibacillus is a genus of bacteria, originally included within Bacillus. The name reflects this fact: Latin paene means almost, and so the Paenibacilli are literally almost Bacilli. The genus includes P. larvae, which causes American foulbrood in honeybees.

Characteristics
Formally considered a morphotype of B. subtilis, Paenibacillus species display complex patterns including the T type (tip-splitting), the C type (chiral), and the V type (vortex). These forms are stably inherited and exhibit many physiological and genetic traits distinct from B. Subtilis including β-galactosidase-like activity causing colonies to turn blue on X-gal plates and multiple drug resistance (MDR) (ampicillin, tetracycline, spectinomycin, and streptomycin. Drug resistance is not shown in liquid media, that is why this particular resistance is believed to be due to a surfactant-like liquid front that actually forms a particular pattern on the petri plate. Although drug resistance and the presence of the B-gal gene as well as their particular morphology on the petri plate are used to identify and characterize the species visually, because of their drug resistance it is very difficult to find selective criteria for mutant strains and therefore to select for insertion sequences flagged with drug resistance genes.