Evaluation of sol-gel silica matrices as inoculant carriers for Mesorhizobium loti

ALVAREZ GS; PIECKENSTAIN FL; DESIMONE MF; ESTRELLA MJ; RUIZ OA; DÍAZ LE

Current Research, Technology and Education Topics in Applied Microbiology and Microbial Biotechnology

Formatex Research Center

Lugar: Badajoz; Año: 2010; p. 160 - 167

The aim of this work was to evaluate the potential of sol-gel silica matrices as alternative supports for long-term storage of rhizobia at room temperature. For this purpose Mesorhizobium spp. cells, which develop nitrogen-fixing nodules in narrow leaf birdsfoot trefoil (Lotus tenuis) roots, were used as the experimental system. Sodium silicate was used for the immobilization of rhizobia. The effect of additives such as glycerol and TY medium over immobilized bacteria viability were also evaluated. Sol-gel immobilized bacteria were found to retain their viability, metabolic activity and nodulation capability after 360 days stored at room temperature. The number of viable cells in soil inoculated with immobilized bacteria was higher than that inoculated with a bacteria suspension. Moreover, silica matrices have the ability to protect entrapped bacteria against acid conditions. The immobilization of rhizobia in sol-gel silica matrices was explored for the first time in this work and has been proven to be an efficient technological tool for the protection and preservation of cells for long periods of time at room temperature and at various pHs. Moreover, this technology can be extended for the delivery of rhizobia or other beneficial bacteria to soils.