Osmoprotective properties of sucrose against nodule bacteria inoculants for legumes

FSBSI All-Russian Research Institute of Agricultural Microbiology, 196608, Pushkin-8, Podbelskogo Highway, 3, St. Petersburg, Russia

^* Corresponding author: laktionov@list.ru

Abstract

In this study, the resistance of soybean nodule bacteria B. japonicum st. 634b, A21, H9 to drying on inoculated soybean seeds of the EN Argenta variety was studied and the effectiveness of sucrose as an osmoprotector of rhizobia was determined. To assess the degree of rhizobia resistance to osmotic stress, soybean seeds were treated with an aqueous solution of the corresponding bacterial culture (control variants) or 20% sucrose solution (experimental variants). Further, the treated seeds were periodically washed with sterile water, followed by determining the number of viable cells by sowing a series of 10-fold dilutions on Petri dishes with agarized nutrient medium, followed by counting the characteristic bacterial colonies formed. Washes were performed 1,2,3,4, and 7 days after seed treatment. It was shown that among the studied strains, strain H9 is the most osmotically stable, and strain 634b is the least. Osmoprotective activity of a 20% sucrose solution was revealed against all three types of rhizobia, which was expressed in a significant slowdown in the rate of reduction of the number of viable cells on inoculated seeds over time.