Asian Journal of Biotechnology and Bioresource Technology https://journalajb2t.com/index.php/AJB2T <p style="text-align: justify;"><strong>Asian&nbsp;Journal of Biotechnology and Bioresource Technology (ISSN:&nbsp;2457-0125)&nbsp;</strong>aims to publish&nbsp;high quality papers (<a href="/index.php/AJB2T/general-guideline-for-authors">Click here for Types of paper</a>)&nbsp;in all areas of Biotechnology and Bioresource Technology. The journal also encourages the submission of useful reports of negative results. This is a quality controlled,&nbsp;OPEN&nbsp;peer reviewed, open access INTERNATIONAL journal.&nbsp;</p> SCIENCEDOMAIN international en-US Asian Journal of Biotechnology and Bioresource Technology 2457-0125 Studies on Bioethanol Production with Thermo Tolerant Yeast Isolates and their Co-Cultures using African Wild Cocoyam as Feedstock https://journalajb2t.com/index.php/AJB2T/article/view/30105 <p>In this work different ways of optimally producing bioethanol at various pH with thermotolerant yeasts and their cocultures using a non-human edible starchy food as feedstock was examined. African wild cocoyam, <em>Xanthosoma roseum</em>, sourced from abandoned farmlands in Obukpa, Nsukka, Nigeria was used as the substrate, while strains of <em>Kluyveromyces marxianus</em> and <em>Pichia stipitis</em> were used to ferment them. First the tubers were gelatinized by boiling under pressure above 100<sup>o</sup>C before hydrolysis with concentrated H<sub>2</sub>SO<sub>4</sub>. The hydrolysates were then fermented at 35<sup>o</sup>C with the thermotolerant yeasts for five days at different pH. Results obtained showed that gelatinized sample of the substrate gave optimum glucose yield when hydrolysed with 1M H<sub>2</sub>SO<sub>4 </sub>for 60 minutes. <em>Kluyveromyces marxianus</em> produced more ethanol than <em>Pichia stipitis</em> at all the four fermentation pH values tested. However, optimum ethanol production was obtained when the two yeast strains were used as coculture at pH 4.5. The peak time for ethanol production was 96 hours for the individual yeast cultures while that of their coculture was 72 hours. The results of the study indicated that wild cocoyam is an excellent feedstock for bioethanol production with many advantages including being non-edible, thereby eliminating concerns for food security, and containing high amount of carbohydrate. The study also revealed that fermenting sugar hydrolysates with a coculture of microorganisms during bioethanol production is a more efficient process than using individual cultures.</p> I. Nnamchi Chukwudi U. Nwachi OkeChukwu A. Ndubuisi Ifeanyi C. Amadi Onyetugo ##submission.copyrightStatement## 2021-07-03 2021-07-03 1 10 10.9734/ajb2t/2021/v7i430105