Evaluation of Brown Midrib Sorghum Mutants as a Potential Biomass Feedstock for 2,3-Butanediol Biosynthesis

Three sorghum backgrounds [Atlas, Early Hegari (EH), and Kansas Collier (KC)] and two bmr mutants (bmr6 and bmr12) of each line were evaluated and compared for grain and biomass yield, biomass composition, and 2,3-butanediol production from biomass. The data showed that the bmr6 mutation in EH background led to a significant decrease in stover yield and increase in grain yield, whereas the stover yield was increased by 64% without affecting grain yield in KC background. The bmr mutants had 10 to 25% and 2 to 9% less lignin and structural carbohydrate contents, respectively, and 24 to 93% more non-structural sugars than their parents in all sorghum lines, except EH bmr12. The total fermentable sugars released were 22 to 36% more in bmr mutants than in parents for Atlas and KC, but not for EH. The bmr6 mutation in KC background produced the most promising feedstock, among the evaluated bmr mutants, for 2,3-butanediol production without affecting grain yield, followed by KC bmr12 and Atlas bmr6, but the bmr mutation had an adverse effect in EH background. This indicated that the genetic background of the parent line and type of bmr mutation significantly affect the biomass quality as a feedstock for biochemical production

Effects of bacterial inoculants and an enzyme on the fermentation quality and aerobic stability of ensiled whole-crop sweet sorghum

________________________________________________________________________________ Abstract A study was conducted to evaluate the effects of bacterial inoculation and cellulase on the fermentation quality of ensiled whole-crop sweet sorghum (WCSS, Sorghum bicolor L. Moench). The WCSS (323 g dry matter (DM)/kg, 251 g water soluble carbohydrates (WSC)/kg DM, 43 g crude protein (CP)/kg DM and 439 g neutral detergent fibre (NDF)/kg DM) was ensiled with i) no additive (control); ii) Lactobacillus buchneri (LB); iii) Lactobacillus plantarum (LP); and iv) LB+E, a combination of LB and enzyme. These treatments were ensiled in 1 L anaerobic jars for 25 days. The jars were opened on days 3, 7 and 15 to determine pH, while those of day 25 were sampled to determine nutrient composition, fermentation characteristics and aerobic stability. Inoculation reduced pH, butyric acid and ammonia-N and increased lactic acid content in sweet sorghum silage compared with the control. The aerobic stability of WCSS was improved with LB, while it was reduced with the homofermentative LP treatment compared with the control. The LB+E reduced the fibre, but increased residual WSC of silage. The aerobic stability of LB+E silage was lower than LB treated silage. Using enzymes to increase the WSC content of crops that already have high levels of WSC may result in reduced aerobic stability of silage. Further work is needed to evaluate these effects on silage produced on farm scale and on animal production performance. _______________________________________________________________________________