Biopolymers in the conservation of rizobacteria cells in alternative culture media

Abstract

The inoculants are formulated with microorganisms of beneficial action for plants in a simple and accessible composition. They need a quality carrier that guarantees the concentration of active cells, in addition to tolerating variations in temperature, humidity, aeration and storage time without presenting high levels of contaminants, making it necessary to use preservatives. Polymers such as carboxymethylcellulose (CMC) and xanthan gum (XG) have been used for the manufacture of inoculants related to their ability to limit heat transfer, and to their rheological properties, which is the measure of the viscosity and flow strain. Thus, the objective of this work was to evaluate the efficiency of these biopolymers in the preservation of Bradyrhizobium elkanii, Bradyrhizobium diazoefficiens and Azospirillum sp. in alternative culture media with 7, 15, 30 45, 60, 90, 120, 150, 180 and 210 days at 5 °C. The inoculants were evaluated at 210 days, checking the pH and counting CFU mL^-1 from the plating using the Spread Plate technique. It was concluded that the use of biopolymers was efficient in the conservation and viability of microorganism cells during the storage period, being the culture medium MS2 that obtained the best results in UFC mL^-1, obtaining at 210 days 3.0 x10⁸ CFU mL^-1 with use of CMC e 1.4 x10⁸ CFU mL^-1 with XG for B. elkanii, 1.3 x10⁷ CFU mL^-1 with CMC, and 6.0 x10⁶ CFU mL^-1 with XG for B. diazoefficiens, 8.5 x10⁸ CFU mL^-1 with XG for Azospirillum sp.