SOLID MEDIUM FOR THE GENETIC MANIPULATION OF THIOBACILLUS-FERROOXIDANS

A new solid medium, termed solid 2:2 medium, was developed for applica tion to the genetic manipulation of Thiobacillus ferrooxidans. The med ium contains a mixture of both ferrous iron and thiosulphate as energy sources for the growth of T. ferrooxidans at pH 4.6-4.8. Kanamycin an d streptomycin could be used in the medium to select recombinants. Tho usands of interspersing colonies can develop on each plate without any iron-oxidizing zones. T. ferrooxidans colonies on solid 2:2 medium ha ve distinct morphologies, and several types of colonies were described . A new type of colony morphology variant with high mutation and rever sion rates was also observed.