Process Optimization of Bioethanol Production by Stress Tolerant Yeasts Isolated From Agro-Industrial Waste

Abstract

The need of Bioethanol or biofuel is increasing worldwide day by day due to renewable resources and ease of production form cheap raw materials. There are several factors that affect on bioethanol production by using yeast. The main objective of this research work was to isolate stress tolerant yeast from agro industry and optimize a process for ethanol production by considering all the factors. Several fermentation batches were carried out by 3 stress tolerant strains varying temperature, pH, sugar concentration, aeration, immobilization and metal ions. From different experiments it was found that temperature 30°C, reducing sugar concentration ranged between 5-6%, pH between 5.0-6.0 and shaking condition were optimum for maximum yield of ethanol by strains Saccharomyces unisporous (P), Saccharomyces cerevisiae (C) and (T).The Bioethanol production capacity of yeasts were found P-15.00%, C-12.50% and T-10.15%at pH 6.0, 30 o C temperature in media with 5.5% initial reducing sugar concentration in shaking condition (115 rpm).Pilot scale ethanol production by P strain was 13.10%, C strain 11.15% andT strain 9.80% at 60 hours. Immobilized cells were produced more ethanol than free cells with same culture conditions. Effect of potassium, magnesium, chromium and boron was investigated on ethanol production. Potassium, Magnesium was shown stimulatory effect on ethanol production.

PERBAIKAN BIOPROSES UNTUK PENINGKATAN PRODUKSI BIOETANOL DARI MOLASE TEBU / Bioprocess Improvement for Enhanching Bioethanol Production of Sugarcane Molase

“…Hasil penelitian Fakruddin et al, (2013) menunjukkan bahwa produksi etanol menggunakan tiga strain S cerevisiae yaitu P, C, dan T, diperoleh hasil yang berbeda-beda. Strain P dan C menghasilkan produksi maksimum pada pH 5,5 setelah 60 jam.…”

“…Peningkatan atau penurunan konsentrasi gula reduksi akan menurunkan hasil etanol. Fakruddin et al, (2013) menguji tiga strain S. cereviseae dalam aplikasi gula reduksi pada awal konsentrasi 5 -6% selama 60 jam, dan diperoleh produksi etanol maksimum bila dibandingkan pada konsentrasi gula reduksi lebih dari 6%. Sedangkan menurut Wardani dan Pertiwi (2013), konsentrasi gula sebesar 15% dapat menghasilkan etanol maksimum sebesar 8,792%.…”

“…Menurut Fakruddin et al, (2012), pemberian suplemen garam logam tembaga sulfat (CuSO4) dapat menurunkan produksi etanol, namun pemberian suplemen kalium dikromat (K2Cr2O7) dan asam borat dapat meningkatkan produksi etanol. Pada penelitian berikutnya, penggunaan tiga strain S. cerevisiae yaitu strain P, C, dan T, dan penambahan kalium dikromat dengan konsentrasi 0,04% dapat meningkatkan produksi etanol masing-masing sebesar 15,50%, 14,64%, dan 13,53% (Fakruddin et al, 2013). Nofemele et al, (2012) melaporkan adanya pengaruh baik dari pemberian urea.…”

Introducing Textiles as Material of Construction of Ethanol Bioreactors

“…Bioethanol fermentation takes place under slightly acidic conditions (pH between 4 and 6), temperatures ranging from 25 to 38 °C, generally without oxygen, and in a liquid medium. Ensuring that only the desired microorganism is what grows in the bioreactor is necessary to ensure the fermentable sugars are converted to the product of interest [15]. It is essential that the material used for constructing bioreactors for producing bioethanol does not affect the fermentation process and can be sterilized when needed.…”

“…Temperature control is essential for optimal product formation as every microorganism has a temperature range in which it functions optimally. For anaerobic condition that for S. cerevisiae is around 30 °C [15]. For lab scale production heat is normally added to the system while for the large industrial bioreactors with low surface to volume ratio, cooling is necessary [11].…”