Growth and disinfestation of 6 different bacteria in embryogenic suspension cultures of cotton.

Growth of 6 different common laboratory bacteria (Escherichia coli, Flavobacterium balustrum, Xanthomonas maltophilia, Enterobacter cloacae, Pseudomonas fluorescens, and Agrobacterium tumefaciens) in a bacterial medium, fresh plant medium, and "spent" plant media was initially measured. In all cases, bacteria grew best in the bacterial medium followed by the fresh plant medium. The spent plant medium did not support growth of the bacteria and apparently was actively toxic to bacterial cells. Proliferating, embryogenic suspension cultures of cotton (Gossypium hirsutum) were then inoculated with these 6 different bacteria. Two to three d following bacterial inoculation, embryogenic tissues were placed in various concentrations of bleach for various amounts of time, rinsed with sterile water, and placed on a bacterial culture medium. Clumps of embryogenic tissue which showed no visible bacterial growth after 3 d of culture were then transferred to an agar-solidified plant tissue culture medium to determine viability of bleachdisinfested tissues. Viable, single pieces of the disinfested embryogenic tissue were then used to reinitiate embryogenic suspension cultures. Treatment of contaminated tissue with a 1% bleach solution for 1-5 min resulted in the highest recovery of viable, disinfested tissues using 5 of the 6 bacteria. It was not possible to remove F. balustrum from clumps of embryogenic tissue without also killing the plant tissue.