CONICET | Buscador de Institutos y Recursos Humanos

Bacterial chemotaxis is a primitive mechanism by which bacteria reponds to high concentrations of attractants and is activated by changes in pH, temperature, osmolarity, viscosity and chemical compounds, some of which are nutrients and secondary metabolites. Most motile bacteria can sense and respond to low concentration by this process. There is evidence that chemotaxis can enhance biodegradation, presumably by rapidly bringing cells into close contact with degradable substrates.Isolates AR92 and AR 109, related to <i>Paenibacillaceae</i> were obtained from bagasse liquor and the batteries in active fermentation for the production of paper, according to their ability to produce xylanases at pH conditions between 5 and 6 at a temperature of 25 to 30º C. Both isolates were Gram + bacillus, mobile, catalase positive. Scanning electron microscopy showed the presence of polar flagella in both strains, as a physiological property related to bacterial motility. Swimming ability related with chemotaxis of both isolates was evaluated in minimal media with birchwood xylan and hemicellulose extracted from sugar cane bagasse with the addition of Tween 80 at two concentrations: 0.02% and 0.2% and minerals salts. Plates were solidified by using agarose 0.3% and incubated at 30 º C for 48h. Results showed that AR 109 exhibited higher swimming, apparently masking clarification of medium due to xylan hydrolysis. This effect was significantly enhanced when calcium and magnesium salts as well as Tween 80 were added to final concentrations of 20 mM and 0.2%, respectively. Isolated AR92 behavior was different, showing smaller colonies with clarification halos of xylan hydrolysis and bigger hydrolytic halos when Tween 80 was added. As a whole, behavior of both isolates tested was for the most part modified by salts and Tween 80 additions to the media. Regarding the carbon source both, colony size and halos were higher when birchwood xylan was used.