Symbiotic potential and survival of native rhizobia kept on different carriers

Abstract

Native rhizobia are ideal for use as commercial legume inoculants. The characteristics of the carrier used to store the inoculants are important for the survival and symbiotic potential of the rhizobia. The objective of this study was to investigate the effects of peat (PEAT), perlite sugarcane bagasse (PSB), carboxymethyl cellulose plus starch (CMCS), and yeast extract mannitol supplemented with mannitol (YEMM) on the survival, nodulation potential and N2 fixation capacity of the native strains Sinorhizobium mexicanum ITTG R7T and Rhizobium calliandrae LBP2-1T and of the reference strain Rhizobium etli CFN42T. A factorial design (4 × 3) with four repetitions was used to determine the symbiotic potential of the rhizobial strains. The survival of the strains was higher for PEAT (46% for strain LBP2-1T, 167% for strain CFN42T and 219% for strain ITTG R7T) than for the other carriers after 240 days, except for CFN42T kept on CMCS (225%). All the strains kept on the different carriers effectively nodulated common bean, with the lowest number of nodules found (5 nodules) when CFN42T was kept on CMCS and with the highest number of nodules found (28 nodules) when ITTG R7T was kept on PSB. The nitrogenase activity was the highest for ITTG R7T kept on PEAT (4911 μmol C2H4 per fresh weight nodule h−1); however, no activity was found when the strains were kept on YEMM. Thus, the survival and symbiotic potential of the rhizobia depended on the carrier used to store them.

Effect of plant growth-promoting bacteria on the growth and fructan production of Agave americana L.

“…The plants were inoculated with 2 mL of a suspension of each PGPB strain at a concentration of 1 × 10 6 UFC mL −1 . 30 , 32 Uninoculated plants and others treated with 30 mg of KNO 3 -N per plant served as controls. Four replicates were used per treatment, and the plants were arranged in a completely randomized design.…”

Biofertilizers: An ecofriendly technology for nutrient recycling and environmental sustainability

“…Dry inoculants are dried by using freeze drying, air drying, dessication and spray drying. Spray drying and shade drying are low-cost methods while the methods like lyophilization as well as spray drying are equipment-based methods and are energy intensive due to which they are expensive ( Ruíz-Valdiviezo et al, 2015 ; Berninger et al, 2017 ; Basheer et al, 2018 ). Freeze drying is a soft dehydration method having a cell protector mixed with the bacterial cells ( Wessman et al, 2013 ; Berninger et al, 2016 ; Tamreihao et al, 2016 ).…”

Revealing potential functions of hypothetical proteins induced by genistein in the symbiosis island of Bradyrhizobium japonicum commercial strain SEMIA 5079 (= CPAC 15)

“…Transferases and hydrolases, each one containing four and three HPs, respectively, another protein was categorized as lyase, one as oxidoreductase, one as hydrogenase (chaperone), and one as ligase. Enzymes play several critical roles in rhizobia, being necessary for bacterial survival and nutrition [ 37 ], nodulation process [ 38 ], adaptation to stressful environments [ 39 ], competitiveness [ 40 ], growth in free-living conditions [ 30 ], physiological and metabolic processes [ 41 ], and virulence ability [ 33 ]. Saprophytic ability and competitiveness are important features to a successful symbiosis and in SEMIA 5079 these genes are located in the symbiosis island.…”