On the Optimization of Fermentation Conditions for Enhanced Bioethanol Yields from Starchy Biowaste via Yeast Co-Cultures

Abstract

The present study aims to assess the impact of the type of yeast consortium used during bioethanol production from starchy biowastes and to determine the optimal fermentation conditions for enhanced bioethanol production. Three different yeast strains, Saccharomyces cerevisiae,Pichia barkeri, and Candida intermedia were used in mono- and co-cultures with pretreated waste-rice as substrate. The optimization of fermentation conditions i.e., fermentation time, temperature, pH, and inoculum size, was investigated in small-scale batch cultures and subsequently, the optimal conditions were applied for scaling-up and validation of the process in a 7-L fermenter. It was shown that co-culturing of yeasts either in couples or triples significantly enhanced the fermentation efficiency of the process, with ethanol yield reaching 167.80 ± 0.49 g/kg of biowaste during experiments in the fermenter.

Artificial microbial consortia for bioproduction processes

“…Hashem et al cultivated a consortium of S. cerevisiae, Pichia barkeri, and Candida intermedia on hydrolyzed rice waste, resulting in almost complete consumption of the sugars contained and an ethanol yield of 0.167 g g -1 or 96% of theoretically possible conversion, compared to 74.3 -80.3% with respective monocultures using a 7 L bioreactor [71]. Similarly, Pathania et al fermented hydrolyzed apple pomace waste with S. cerevisiae and Scheffersomyces stipitis to produce 34.46 g L -1 ethanol, which was further improved by immobilization to a maximum of 44.46 g L -1 [72].…”

“…Hashem et al. cultivated a consortium of S. cerevisiae , Pichia barkeri , and Candida intermedia on hydrolyzed rice waste, resulting in almost complete consumption of the sugars contained and an ethanol yield of 0.167 g g –1 or 96% of theoretically possible conversion, compared to 74.3 – 80.3% with respective monocultures using a 7 L bioreactor [ 71 ]. Similarly, Pathania et al.…”

Artificial Consortia of Bacillus Amyloliquefaciens HM618 and Bacillus Subtilis for Utilizing Food Waste to Synthetize Iturin A

“…It is well known that the degradation of complex substrates, such as food waste, is the rate-limiting step for microbial fermentation (Choi et al 2018). Usually, it is preferred to add commercial enzymes to degrade FW into small energy molecules that can be directly used by microorganisms (Rishi et Presently, the co-cultivation technology has been favored for the transformation of complex substrates into value-added products, by virtue of its advantages in the minimal operational cost and synergistic metabolism of two or more organisms (Mohapatra et al 2020;Izmirlioglu and Demirci 2017;Hashem et al 2021). Using FW as the substrate, two-strains consortia containing enzyme-producing fungus and B. amyloliquefaciens HM618 were constructed to produce surfactin (Pan et al 2021).…”

Efeito da contaminação microbiana de amostras de matérias-primas no rendimento etanólico da fermentação.

“…Concentrações baixas de inóculo pode aumentar demasiadamente o período de fermentação. E, concentrações iniciais de inóculo maiores tendem a aumentar a velocidade de formação de etanol (AZHAR et al, 2017;HASHEM et al, 2021;WANDERLEY;GOUVEIA, 2014). Os ensaios na terceira seção deste projeto foram conduzidos em mosto misto 80:20% v·v -1 variando a concentração inicial de inóculo em 2,5% m·v -1 , 5,0% m·v -1 e 7,5% m·v -1 , em massa úmida.…”

“…A concentração do inóculo afeta os parâmetros cinéticos na fermentação do etanol (AZHAR et al, 2017;HASHEM et al, 2021). O aumento da concentração de inóculo está relacionado ao aumento da concentração de biomassa, da taxa máxima de consumo e da taxa máxima de crescimento (TURHAN et al, 2010).…”