Biotechnological Potential of Soybean Plant Growth-Promoting Rhizobacteria

Abstract

Technologies that use rhizobacteria to promote plant growth are increasing in agriculture, results have shown improvements in soil quality, increases in productivity, and decreases in the use of synthetic inputs, The objective of work was to characterize bacterial isolates regarding their biological activity and growth promotion of soybean plants grown in a controlled environment. Fifteen bacteria were isolated from soils with continuous use of biological fertilizer. They were evaluated for enzymes production (amylase and protease), nitrogen fixation, antagonistic activity to phytopathogenic fungi, and indoleacetic acid (IAA) production, Soybean seeds were inoculated with bacterial isolates in a greenhouse and evaluated for plant development and soil chemical attributes. The results showed that 8 of the 15 isolates presented production of amylase, protease, or both and 4 isolates presented nitrogen-fixing capacity. The percentage of isolates with high or moderate inhibitory action against the fungi Sclerotinia sclerotiorum, Macrophomina phaseolina, and Fusarium solani were 73.3%, 66.6%, and 73.3%, respectively. The IAA production varied from 8.56 to 31.33 µg mL-1 (5 isolates had low, 6 had moderate, and 4 had high production). The soybean development was significantly higher in 80% of the treatments with inoculation with bacterial isolates. Five bacterial isolates effectively present all characteristics for use as inoculant (biofertilizer) to promote the development of soybean plants.

Effect of the digestibility of cassava flour (Manihot esculenta crantz) by enzymes extracted from corn malt

“…According to Malumba et al (31), this phenomenon activates at 70°C for barley malt amylase and above, which is well below the optimal temperature of α-amylase but close to that of β-amylase. Indeed, the likely optimal temperatures for β-amylase would be at 50°C, and for α-amylase at 90°C (25). The concentrations did not have signi cant differences, which shows that these concentrations can also be used on an industrial scale to digest cassava starch by corn malt enzymes.…”

“…The digestibility of cassava our by corn enzymes or simply the hydrolysis of its starch will depend on the choice of the right temperature and pH conditions. Paula et al (25) reports that the success of the malting process of corn will depend on this. This is a process that has as its objective the development of enzymes, the disaggregation of the constituents of the grain (starch, proteins, wall, etc.)…”

“…The choice of starch hydrolysis conditions is also one of the key factors in the success of this process (hydrolysis). Paula et al (25) reports that α-amylase retains 80% activity in a pH range between 4.0 and 6.5. This is similar to literature reports, as the optimal pH of most α-amylases have been reported between pH 4.5 and 6.5 (26-27-28-29-30).…”

“…Studies conducted by Paula et al (25) determined the different temperatures for a good response of amylase enzymes. These are 50°C for the activity the optimal temperature of β-amylase and 90 ° C optimal temperature the α-amylase β-amylase, and 90°C for the α-amylase activity.…”