Escherichia coli K12 strain

Bacteria. Supplied as a culture in a glass bottle.

Q = What's the difference between E. Coli K12 Strain and E. Coli B Strain?
A = Escherichia coli is a Gram-negative, facultatively anaerobic, rod-shaped bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms. B Strain is susceptible to T4 bacteriaphage where as K12 is not.
 

Q = Is this Lac+?
A = This culture is Lac+ (Lactose-fermenting).