Identification of strain isolated from dates (Phœnix dactylifera L.) for enhancing very high gravity ethanol production

Abstract

Ethanol production from by-products of dates in very high gravity was conducted in batch fermentation using two yeasts, Saccharomyces cerevisiae and Zygosaccharomyces rouxii, as well as a native strain: an osmophilic strain of bacteria which was isolated for the first time from the juice of dates (Phoenix dactylifera L.). The phylogenetic analysis based on the 16S ribosomal RNA and gyrB sequence and physiological analysis indicated that the strain identified belongs to the genus of Bacillus, B. amyloliquefaciens. The ethanol yields produced from the syrup of dates (175 g L and 360 g L of total sugar) were 40.6% and 29.5%, respectively. By comparing the ethanol production by the isolated bacteria to that obtained using Z. rouxii and S. cerevisiae, it can be concluded that B. amyloliquefaciens was suitable for ethanol production from the syrup of dates and can consume the three types of sugar (glucose, fructose, and sucrose). Using Z. rouxii, fructose was preferentially consumed, while glucose was consumed only after fructose depletion. From this, B. amyloliquefaciens was promising for the bioethanol industry. In addition, this latter showed a good tolerance for high sugar concentration (36%), allowing ethanol production in batch fermentation at pH 5.0 and 28 °C in date syrup medium. Promising ethanol yield produced to sugar consumed were observed for the two osmotolerant microorganisms, Z. rouxii and B. amyloliquefaciens, nearly 32-33%, which were further improved when they were cocultivated, leading to an ethanol to glucose yield of 42-43%.

Isolation and Identification of Yeast Strains From Sugarcane Molasses, Dates and Figs for Ethanol Production Under Conditions Simulating Algal Hydrolysate

“…Concerning efficiency, it increased from 52 and 59% for S2 and S3, respectively, in the monoculture to 68% in the co-culture of S2 and S3. Djelal et al (2017) showed that the fermentation of by-products of dates by co-cultures of the isolated strain B. amyloliquefaciens and Z. rouxii showed an increase of the yield of ethanol by 12.5% compared with the single culture; they also demonstrated that the strain ratio did not affect the results of ethanol productivity. Kalyani et al (2013) observed that the co-culture of S. cerevisiae and Pichia stipitis produced 23% and 38% more ethanol than the amounts produced by S. cerevisiae and P. stipitis in pure cultures.…”

“…Various microorganisms of indigenous strains capable of producing ethanol have been isolated from different local sources such as dates (Djelal et al, 2017), different fruits (Lee et al, 2011), cheese whey (Boudjema et al, 2016), sugar cane and beet molasses (Hamouda et al, 2016). However, strains isolated from the natural substrate gave much better performance than commercial strains (Djelal et al, 2017). It should also be noted that the production of ethanol in cocultures allows higher results than single cultures.…”

“…For example, the co-immobilization of Saccharomyces cerevisiae and Scheffersomyces stipitis in an immobilized cell reactor increased ethanol production by 10% compared with a single culture of S. cerevisiae (Karagor and Ozkan, 2014). The co-culture of Bacillus amyloliquefaciens and Zygosaccharomyces rouxii from syrup of dates improved the yield of ethanol production by 25% compared with a single culture of Z. rouxii (Djelal et al, 2017). Some studies show a simultaneous improvement of saccharification and bioethanol production from industrial effluent with co-culture of Bacillus subtilis and S. cerevisiae (Tantipaibul et al, 2015), from industrial potato waste with co-culture of Aspergillus niger and S. cerevisiae (Izmirlioglu and Demirci, 2016), and from kitchen biowaste with S. cerevisiae and Pichia stipitis (Ntaikou et al, 2018) Several methods can be used for the identification of isolated strains.…”

Bioethanol Production from Sugarcane Molasses by Engineered Strain Lactobacillus Casei E1

“…It can affect the growth and metabolism of the strain, causing the dehydration and inactivation of protein, which hinder cell cycle and inhibit cell growth (Radmaneshfar et al 2013). Some studies have found that, with the increase of osmotic stress, the cell will actively regulate osmosis that causes intracellular water out ow, shrinking of cells, and even death (Djelal et al 2017).…”

Process engineering for pollution control and waste minimization

“…The objective was to treat the grey water for agricultural and industrial purposes. Djelal et al (2017) have identified a strain isolated from dates, which is able to enhance high gravity ethanol production.…”