High production of fructooligosaccharides by levansucrase from Bacillus subtilis natto CCT 7712

Fructooligosaccharides (FOSs) are fructose oligomers known as prebiotics that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improving host’s health. FOS can be produced by the action of fructosyltranferases from microorganisms, including the Bacillus subtilis natto. The objective of the present study was applying response surface methodology in order to optimize the FOS production by levansucrase from B. subtilis natto CCT 771. The variables evaluated were sucrose concentration, pH and temperature. From the analysis of the results, the significant variables were pH and sucrose concentration (p < 0.05). Levansucrase of B. subtilis natto synthesized fructooligosaccharides in all experimental conditions, showing its potential for use in an industrial process of producing FOS from sucrose. The use of response surface methodology allowed the determination of the concentration of sucrose (334 g.L-1), pH (6.0) and temperature (45.8°C) for a maximum yield of 54.86 g.L-1 FOS.Keywords: Fructooligosaccharides, Bacillus subtilis, levansucrase, prebiotics.African Journal of Biotechnology Vol 13(27) 2734-274

Detached leaf culture: Viability to evaluate 2,4-D toxicity symptoms in cotton apex leaves

To study the viability of detached leaf culture technique, studies were carried out with detached leaves from cotton apex (true trilobed leaves). The prepared leaves were sprayed with 2,4-D amine and ester, at rates of 10, 30, 70, and 100% of the recommended doses. Detached leaves without herbicide spray were used as controls. Simultaneously, a greenhouse experiment was conducted with the same treatments as used for the detached leaves experiment. Toxicity was measured through a 0-to-5 grading according to the percentage of affected leaf area in the detached leaves experiment or examining the affected rate of whole plant as indicated in the greenhouse. Results showed that the ester form of the herbicide induced earlier and more severe toxicity symptoms in detached leaves and greenhouse grown plants. Positive and significant correlations (p < 0.001) were found between toxicity results obtained at 7 and 14 days after application in detached leaves and greenhouse plants (r = 0.97 and 0.92, respectively). Negative, significant correlations (p < 0.005) were found between the toxicity levels found at 7 and 14 days after application in detached leaves and dry matter of cotton plants grown in the greenhouse (r = -0.92 and -0.92, respectively)