Bioethanol production from cassava peels using different microbial inoculants

The potential of bioethanol production using different microbial inoculants for the simultaneous saccharification and fermentation of cassava peels from three cassava cultivars was investigated. Peels obtained from three cassava cultivars namely TME 0505, TME 419 and TME 4779, were washed, dried in a laboratory air oven dryer at 120°C for 3 h, ground into a fine texture and sieved with 1.5 μ nylon sieve. The sieved material was cultured using the following inoculant combinations: A = Rhizopus nigricans + Saccharomyces cerevisiae; B = Aspergillus niger + Saccharomyces cerevisiae; C = Rhizopus nigricans + Aspergillus niger + Saccharomyces cerevisiae; D = Rhizopus nigricans + Spirogyra africana + Saccharomyces cerevisae; E = Aspergillus niger + Spirogyra africana + Saccharomyces cerevisiae. These combinations have not been tested before on cassava peels. The control was inoculated with S. cerevisiae only. The cultures were distilled on the 21st day and the quantity of ethanol produced in each treatment group recorded. Results obtained showed significant differences (P<0.05) in the amount of ethanol produced and in its concentration among the five inoculants. Significant differences (P<0.05) were also obtained in ethanol yield from the three cassava varieties. Cassava peels from TME 4779 gave the highest ethanol yield of 14.46 ± 2.08 g/cm3 using R. nigricans + S. africana+ S. cerevisiae. Similarly, cassava peels from TME 0505 gave the second highest ethanol yield of 13.33 ± 0.67 g/cm3 using the same combination, namely R. nigricans + S. africana + S. cerevisiae. Low ethanol yields of 4.82 ± 1.00, 6.43 ± 0.58 and 7.77 ± 0.88 g/cm3 were obtained from the cassava peels of TME 419, TME 0505 and TME 4779, respectively using S. cerevisiae alone. The yield reported in this study competes favorably with those reported from cassava peels, potato peels and millet husks using other inoculant treatments by other workers. Inoculants used in this study thus showed great potential for bioethanol production from cassava peels.Keywords: Bioethanol, cassava peels, microbial inoculant

Evaluation of Starch Biodegradable Plastics Derived from Cassava and Their Rates of Degradation in Soil

Starch derived from two cassava cultivars, one with high amylose (TMS 92/0325) and the other with high amylopectin contents (TMS 91/02324), were screened for their ability to produce biodegradable plastics using different compositions of plasticizers and other materials. The rate of degradation of the bioplastics produced was equally evaluated. It was observed that the degradation values for bioplastics derived from TMS 92/0325 were 70.0%, 85.4%, 90.2% and 98.6%, while those from TMS 91/02324 were 72.4%, 86.6%, 93.5% and 99.2% at the end of 7 weeks for products containing 45%, 60%, 75% and 90% of starch, respectively. This is an implicit indication that the rate of degradability of the bioplastics produced from cassava does not depend on the level of amylose and amylopectin in the starch per se but rather on the amount of the starch itself that is used in the formulation. Moreover, our results equally demonstrated that bioplastics produced from the starch derived from cultivar TMS 91/02324 had a higher tensile strength than those gotten from cultivar TMS 92/0325. Taken together, these results are suggestive of the fact that though bioplastics produced from starch having a higher amylopectin level would have a higher tensile strength, however, they do not necessarily have a faster and greater rate of degradation when composted.Key words: Amylopectin, bioplastics, cassava starch, degradation, environment, sorbito

EST-SSR development for Digitaria exilis and its relatives D. iburua and D. longiflora from transcriptome sequences

Digitaria exilis is an important indigenous cereal in West Africa. The first fonio reference transcriptome was released and became a key tool for developing new molecular markers contributing to a better understanding of its genetic diversity. A total of 126 new putative primer pairs were successfully designed in 37,327 unigenes from the D. exilis transcriptome. Thirty-seven primer pairs were randomly selected and tested for their ability to cross-amplify to related species. Clear amplification patterns were observed on 24 primer pairs. Of these, 71, 74 and 35% showed polymorphism in three species: D. exilis, D. longiflora and D. iburua. The transferability from D. exilis was 96% to D. longiflora and 71% to D. iburua. The new SSR markers confirmed the close genetic proximity of D. exilis with D. longiflora and its stronger genetic difference of D. exilis from D. iburua. These markers will be valuable for completing future knowledge on Digitaria evolutionary history, and for testing gene flows between related species

Towards conservation and sustainable use of an indigenous crop: A large partnership network enabled the genetic diversity assessment of 1539 fonio (Digitaria exilis) accessions

International audienceThe use of neglected and underutilized species (NUS) in agrosystems is a potential solution to the challenges arising from global change. These species could contribute to the equitable diversification of agricultural systems. Providing knowledge on their genetic diversity and fostering access to data and results is essential for the development of strong collaborative future research. The study addressed these issues by assessing the diversity of the largest fonio (Digitaria exilis) collection existing to date. Associated with a user-friendly Shiny application (https://shinyapps.southgreen.fr/ app/foniodiv), our results reinforce research efficiency and broaden the prospects for all actors involved in enhancing fonio and indigenous crops as valuable resources for the future