Efficient photocatalytic conversion of CH4 into ethanol with O2 over nitrogen vacancy-rich carbon nitride at room temperature

An ethanol production rate as high as 281.6 μmol g−1 h−1 was achieved during the photocatalytic conversion of CH4 in the presence of O2 at room temperature.

Bioethanol Production From Leaves of Quercus Infectoria in Kurdistan Region

Quercus infectoria is one of the most abundant native oak species in the Kurdistan region of Iraq. This study focused on utilizing leaves of Quercus infectoria for ethanol production in the region. A typical three-step conversion process of acid pretreatment, enzymatic hydrolysis, and yeast fermentation was investigated to produce ethanol from the leaves. Under the selected acid pretreatment and enzymatic hydrolysis conditions, the glucose and xylose concentrations in the hydrolysates reached 11.4 g/L and 16.8 g/L, respectively, with the corresponding sugar conversions of 42.8% and 99.8%. A yeast strain, Kluyveromyces marxianus, was used to ferment mono-sugars in the hydrolysates for ethanol production. The ethanol production rate and conversion of K. marxianus in the fermentation were 0.17 g/L/h and 27%. The techno-economic analysis further concluded that a regional ethanol biorefinery can be established in the Zawita sub-district, Iraq to utilize Q. infectoria leaves to produce 200,000,000 kg ethanol/year with a positive energy balance of 745,052,623 MJ/year. The net annual revenue of the biorefinery is $123,692,804. The payback period of the biorefinery is 10 years.

Influence of autoinoculum on basic oenological parameters of wine

In this paper we focus on possibilities of using natural microflora from vineyards to enhance spontaneous fermentation. Obtained yeast isolates, naturally occurring in vineyards, which were previously isolated in 2017 and 2018, were used for inoculation of Hibernal grape must. Spontaneously fermented musts and musts with the yeast isolates from 2017 and 2018 were compared. Basic parameters of the musts (sugar concentration, pH, concentration of titratable acids, concentration of assimilated nitrogen) were analysed studied, and a sensory analysis of the resultant wines was performed. The fermentation with the yeast isolates was quick and smooth. In the spontaneous fermentation lower ethanol production rate was observed at the end of the fermentation process. During the sensory evaluation, fruitiness of the spontaneously fermented batch was lower, but its vegetal characteristic was pronounced. The variant with the yeast isolates from 2017 was described as smooth, and the variant with yeast isolates from 2018 was evaluated as slightly vegetal.

The optimization of the Ambonese arrack fermentation using co-culture Pichia polymorpha and Kloeckera javanica

Mahulette F, Astuti DI. 2020. The optimization of the Ambonese arrack fermentation using co-culture Pichia Polymorpha and Kloeckera javanica. Biodiversitas 21: xxxx. The fermentation process of the Ambonese arrack is still uncontrollable. As various microbes are involved in the fermentation, which causes inconsistent production of ethanol content. This research aimed to optimize the production of the Ambonese arrack using Pichia polymorpha and Kloeckera javanica in inoculum ratios of 1:1, 1:2, and 1:3. The number of yeast cells and chemical characteristics was observed every three hrs up to 24 hrs. The ethanol content of the fermented coconut sap and the arrack was measured using the titration and Gas Chromatography-Mass Spectrophotometry (GC-MS) methods, respectively. The numbers of P. polymorpha and K. javanica cells at 15 hrs of fermentation were 9.9 log CFU/mL and 10.7 log CFU/mL, respectively. The reducing sugar content decreased from 525 mg/L to 296 mg/L, while the pH from 6.46 to 4.82. The highest ethanol production rate was 1.4 mg/L.3hrs. (ratio 1:1), observed at 12 hrs of the fermentation, while the highest ethanol contents in the fermented coconut sap and the arracks were 11.3 mg/L and 300.400 mg/L, respectively. Different inoculum ratios affect the sensory characteristics of Ambonese arrack. The highest average value of sensory testing was 4.6 (ratio 1:2). Thus, the inoculum ratios of P. polymorpha and K. javanica 1:2 and 1:3 has the best quality in controlled Ambonese arrack processing.

Evoked Methane Photocatalytic Conversion to C2 Oxygenates over Ceria with Oxygen Vacancy

Direct conversion of methane to its oxygenate derivatives remains highly attractive while challenging owing to the intrinsic chemical inertness of CH4. Photocatalysis arises as a promising green strategy which could stimulate water splitting to produce oxidative radicals for methane C–H activation and subsequent C–C coupling. However, synthesis of a photocatalyst with an appropriate capability of methane oxidation by water remains a challenge using an effective and viable approach. Herein, ceria nanoparticles with abundant oxygen vacancies prepared by calcinating commercial CeO2 powder at high temperatures in argon are reported to capably produce ethanol and aldehyde from CH4 photocatalytic oxidation under ambient conditions. Although high-temperature calcinations lead to lower light adsorptions and increased band gaps to some extent, deficient CeO2 nanoparticles with oxygen vacancies and surface CeIII species are formed, which are crucial for methane photocatalytic conversion. The ceria catalyst as-calcinated at 1100 °C had the highest oxygen vacancy concentration and CeIII content, achieving an ethanol production rate of 11.4 µmol·gcat−1·h−1 with a selectivity of 91.5%. Additional experimental results suggested that the product aldehyde was from the oxidation of ethanol during the photocatalytic conversion of CH4.

Model-based transcriptome engineering promotes a fermentative transcriptional state in yeast

The ability to rationally manipulate the transcriptional states of cells would be of great use in medicine and bioengineering. We have developed an algorithm, NetSurgeon, which uses genome-wide gene-regulatory networks to identify interventions that force a cell toward a desired expression state. We first validated NetSurgeon extensively on existing datasets. Next, we used NetSurgeon to select transcription factor deletions aimed at improving ethanol production in Saccharomyces cerevisiae cultures that are catabolizing xylose. We reasoned that interventions that move the transcriptional state of cells using xylose toward that of cells producing large amounts of ethanol from glucose might improve xylose fermentation. Some of the interventions selected by NetSurgeon successfully promoted a fermentative transcriptional state in the absence of glucose, resulting in strains with a 2.7-fold increase in xylose import rates, a 4-fold improvement in xylose integration into central carbon metabolism, or a 1.3-fold increase in ethanol production rate. We conclude by presenting an integrated model of transcriptional regulation and metabolic flux that will enable future efforts aimed at improving xylose fermentation to prioritize functional regulators of central carbon metabolism.

Research on Ethanol Production by Biological Fermentation of Potato Pulp

Bioconversion of potato pulp to fuel ethanol, analysing the potato pulp chemical composition and determining the potato pulp in the role of microorganism produce ethanol under the best conditions is the major research. An analysis of the chemical composition of potato pulp showed that : the basic ingredients are Protein (9.72%), Starch (25.52%), Cellulose (17.90%). The effects of ethanol production rate of solid-liquid ratio, fermentation temperature, inoculumconcertration, fermentation time. The results showed that: the best conditions producting ethanol from potato pulp obtained by single factor experiments are: solid-liquid ratio: 1:15, fermentation temperature: 35°C, inoculumconcertration: 3mL, fermentation time: 20h. Under this occasion, the ethanol production rate was 0.183mL·g-1.

Cofermentation of Glucose, Xylose, and Cellobiose by the Beetle-Associated Yeast Spathaspora passalidarum

ABSTRACTFermentation of cellulosic and hemicellulosic sugars from biomass could resolve food-versus-fuel conflicts inherent in the bioconversion of grains. However, the inability to coferment glucose and xylose is a major challenge to the economical use of lignocellulose as a feedstock. Simultaneous cofermentation of glucose, xylose, and cellobiose is problematic for most microbes because glucose represses utilization of the other saccharides. Surprisingly, the ascomycetous, beetle-associated yeastSpathaspora passalidarum, which ferments xylose and cellobiose natively, can also coferment these two sugars in the presence of 30 g/liter glucose.S. passalidarumsimultaneously assimilates glucose and xylose aerobically, it simultaneously coferments glucose, cellobiose, and xylose with an ethanol yield of 0.42 g/g, and it has a specific ethanol production rate on xylose more than 3 times that of the corresponding rate on glucose. Moreover, an adapted strain ofS. passalidarumproduced 39 g/liter ethanol with a yield of 0.37 g/g sugars from a hardwood hydrolysate. Metabolome analysis ofS. passalidarumbefore onset and during the fermentations of glucose and xylose showed that the flux of glycolytic intermediates is significantly higher on xylose than on glucose. The high affinity of its xylose reductase activities for NADH and xylose combined with allosteric activation of glycolysis probably accounts in part for its unusual capacities. These features makeS. passalidarumvery attractive for studying regulatory mechanisms enabling bioconversion of lignocellulosic materials by yeasts.

Tolerance of plum (Prunus domestica L.) fruits stored in low-oxygen atmosphere

Plum fruits of the cultivars Stanley and Valjevka picked at the beginning of climacteric were stored in different storage atmospheres for 31 days at 3°C. The relations between the O₂ and CO₂ content during this period and after removal from the gas mixture to ethanol, acetaldehyde, non-volatile compounds and some textural values of fruits were investigated. Concentrations of ethanol in the flesh were related to levels of oxygen and CO₂ in ambient atmosphere. In anaerobic conditions (< 0.2% O₂) ethanol reached 1,109 mg/l for the cultivar Valjevka and 628 mg/l for Stanley. The results of single fruit analysis showed a steeply increasing concave curve of ethanol production in the period of anaerobic conditions, followed by the phase of a drop of the production rate in air stored fruit. The concentration of oxygen at a level of 0.9% (ultra low oxygen – ULO) does not physiologically harm the tissues of plums by producing mostly negligible content of ethanol and acetaldehyde, but an ethanol increase to half concentration after 31 days was observed to compare with anaerobic conditions in the cultivar Valjevka. From this aspect plums seem to be relatively sensitive to low oxygen. The post-storage period was extended up to 53 to 63 days, respectively. The senescence caused an increase in ethanol production rate that was exponentially increased after 20 days of cold storage atmosphere. The final concentration after 53 days was still higher for cv. Valjevka than for cv. Stanley at the respective content of 828 mg/land 498 mg/l. Skin firmness was differentiated for both cultivars, and softness was higher for the cultivar Valjevka.  

Simultaneous Biohydrogen and Bioethanol Production from Anaerobic Fermentation with Immobilized Sludge

The effects of organic loading rates (OLRs) on fermentative productions of hydrogen and ethanol were investigated in a continuous stirred tank reactor (CSTR) with attached sludge using molasses as substrate. The CSTR reactor with attached sludge was operated under different OLRs, ranging from 8 to 24 kg/m3·d. The H2and ethanol production rate essentially increased with increasing OLR. The highest H2production rate (10.74 mmol/hL) and ethanol production rate (11.72 mmol/hL) were obtained both operating at OLR = 24 kg/m3·d. Linear regression results show that ethanol production rate () and H2production rate () were proportionately correlated and can be expressed as (). The best energy generation rate was 19.08 kJ/hL, which occurred at OLR = 24 kg/m3·d. In addition, the hydrogen yield was affected by the presence of ethanol and acetic acid in the liquid phase, and the maximum hydrogen production rate occurred while the ratio of ethanol to acetic acid was close to 1.