Microorganisms G. diazotrophicus strain 166 (CM-INICA),
isolated from sugarcane, was maintained in N-poor solid medium
(1) containing 10% (w/v) sucrose at pH 5.5. Cultures were maintained
for 5 d at 30C and the formation of acid in parallel to the
culture growth was tested by adding bromothymol blue to the medium
(20). This indicator is green at pH 5.5 and changes to yellow
at pH 5.0.
X. albilineans strain NCPPB 887 was cultured on Willbrink medium
(21), at 37 C.
Plant material, infection and isolation of xanthans Saccharum
officinarum L., cv. Mayarí 55-14, plants were developed
from agamic seeds (segments of stalk internodes containing a
vegetative bud) and grown in field conditions at the Real Jardín
Botánico Alfonso XIII (Complutense University, Madrid) for 7
months.