Pentose sugars present in lignocellulosic hydrolysates or hexuronic acids D-galacturonic acid (abundant in pectin-rich waste streams such as peels and pulps), and glucose can be used negative control.The use of antibiotic selection and positive and negative controls are important elements of interpreting data from a bacterial transformation. In negative control, an active repressor (encoded by the R gene) can be used.Operon regulation can be either negative or positive by induction or repression.

what is the bacteria you are using

you should be able to find E. coli mutants which do not grow on glucoronate

@ Suhas,

I am using Bacillus amyloliquefaciens subsp. plantarum bacteria. Thanks