Abstract

HERNANDEZ-FLORES, Lina et al. Native bacterial populations: Sustainable alternative to agriculture. Terra Latinoam [online]. 2012, vol.30, n.2, pp.129-138. ISSN 2395-8030.

Modern agricultural production requires high amounts of agrochemical derivatives of petroleum. Their production and use contaminate the atmosphere, generating damage to health of living beings. An alternative to the exclusive use of agrochemicals, while maintaining a profitable agricultural production and aiming for sustainable management, is the application of nitrogen fixing microorganisms. In this way, this alternative reduces costs (economic and environmental) without affecting crop productivity. Our objective was to generate a technology with potentially useful native rhizobia strains as biofertilizers, applied to agricultural crops in localities of the state of Chihuahua. In 11 agricultural soil samples, bacterial populations were evaluated, finding levels from 1 × 102 a 6.6 × 103 training units of colonies (UFC g-1); showing the negative effect of chemical fertilizers on microbial soil populations. Some strains showed very low survival capacity in vitro. We obtained a collection of 24 strains isolated from soil and 7 strains isolated from root nodules. The 31 isolates were identified by 16S rDNA sequencing, mainly Rhizobium and Ensifer were found. Growth in culture medium was evaluated under different physiological conditions (pH 4.0, 5.5, 6.8 and 8.0; temperature of 32 and 42 ºC, and NaCl concentration of 0.01, 0.51 and 0.85 mol L-1). Strains with capacity to grow under adverse conditions were obtained. This capacity suggests physiological flexibility and adaptation to environmental conditions. The difference in effectiveness observed for inoculated strains on leguminous crops visibly shows the necessity of multistrain inoculants as an alternative for sustainable agriculture.

Keywords : biofertilizers; leguminous; nodulation; rhizobia.

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