CONICET | Buscador de Institutos y Recursos Humanos

The recycling of photosynthetically fixed carbon through the action of microbial plant cell wall hydrolases is a key biological process. Xylan, one of the most abundant plant structural polysaccharides, is a heterogeneous polymer that requires multiple xylanolytic enzymes to be efficiently hydrolyzed. Moreover, a tight interaction between the enzymes and their substrates and the cooperation of multiple enzymes are also required to enhance hydrolysis due to the complex structures of their substrates, such as endo-1,4-β-xylanase (1,4-β-D-xylanylanohydrolase [EC 3.2.1.8]) and β-xylosidase (EC 3.2.1.37) that cleave the backbone chain and α-L-arabinofuranosidase (EC 3.2.1.55), acetyl esterase (EC 3.1.1.6), and α-D-glucuronidase (EC 3.2.1.1). Several bacteria were isolated from both, sugar cane bagasse and from the liquor that flows through the sugar cane bagasse pile during its pre-treatment for paper production. In this work we report the improvement of xylanase production during aerobic growth of selected isolates preliminary characterized as novel members of <i>Paenibacillaceae</i> according to their 16S rDNA sequence as well as morphologycally and biochemically by using standard procedures. Our results showed that the use of hemicelluloses extracted from sugar cane bagasse as substrate, xylanolytic activity is higher than that obtained with birchwood xylan as a carbon source, which could indicate the adaptation to their natural environment. Enzymatic activities were better when minimal media was supplemented with calcium and magnesium. Furthermore, addition of tween 80 at concentrations ranging from 0.02 to 0.4% to the media led to increments of xylanolytic activities of 50% to 90% for members to <i>Paenibacillaceae</i>, showing different magnitud of effect, no effect or growth inhibition for other bacilli isolated in this work.