Bioconversion of Agro-industrial Wastes into Xanthan Gum

Green coconut shell, passion fruit peel, straw and corn cobs, agro-industrial wastes, were evaluated as alternative substrates for xanthan gum production, which is one of the most important commercial biopolymers obtained by fermentation, widely used in the food industry and with applications in the oil, petrochemical, agrochemical and pharmaceutical industry. The residues were sanitized, dried at 50 degrees C and milled, being subjected to self-hydrolysis with water in a ratio of 9:100 (w:v) at 121 degrees C for 15 minutes with subsequent filtration. The extracted broth was placed in 250 mL Erlenmeyer flasks, supplemented with urea (0.01%) and potassium phosphate (0.1%), pH adjusted to 7.0, sterilized at 121 degrees C for 15 min and then fermented on an orbital shaker at 150 rpm for 100 hours by the bacterium Xanthomonas campestris pv. campestris (1078). The substrate consumption and the production of xanthan gum in green coconut shells (50% and 5.5 g/L) and passion fruit (54.7% and 6.7 g/L) were significantly higher than maize straw (straw - 72.6% (1 g/L) and cob 46.6 (2.2 g/L)).