Yeast Isolates Research Articles

Isolation and identification of yeasts from local fruits in Thua Thien Hue province, Vietnam

In this study, a total of 30 yeast isolates were recovered from local fruits in Thua Thien Hue province. Genetic characterization based on the ITS sequences identified isolates belonging to 3 species including Saccharomyces cerevisiae, Lachancea fermentati, and Clavispora fructus, with high sequence homology (over 99%) compared to published sequences in the GenBank. All identified S. cerevisiae isolates could grow well at 30°C and ferment several sugar including fructose, galactose, sucrose, mannose, maltose, and raffinose with different performances, but were inhibited at temperature higher than 35°C. The strains also grew well in the medium containing 5% ethanol (v/v) and 200 g/L glucose, but their growth ability was decreased gradually with an increase in ethanol and glucose concentrations. Interestingly, D14 strain was able to grow in the medium supplemented with 12% of ethanol, and 500 g/L of glucose at 45°C, while D7 strain could utilize both mannitol and glycerol at a low level. Our results also indicated that some strains have relatively high sedimentation efficiency, which are favorable conditions for beer fermentation and biomass recovery. The isolated yeast strains with good tolerance properties may provide a potential source of valuable raw materials for applications in beverage production and food processing.

Phenol Biodegradation by Free and Immobilized Acinetobacter calcoaceticus K5 and Candida tropicalis YM2 Isolated from Persian Gulf

Phenols exhibit high solubility in water, leading to their potential to contaminate significant volumes of freshwater, wastewater, groundwater, oceans, and soil. The primary objective of this study is to isolate and identify bacterial and yeast isolates with optimal phenol degradation capabilities from Persian Gulf. Sea water and sediment samples were collected to isolate bacterial and yeast isolates, which were then evaluated for their ability to degrade phenol both in their single-cell form and when encapsulated in chitosan and alginate. The phenol-degrading strains were quantified using colony-forming unit (CFU) and most probable number (MPN) methods. The most promising microorganisms were selected and identified using phenotypic and polymerase chain reaction techniques. The selected isolates were immobilized in alginate and chitosan carriers, and their bioremediation potential was assessed at different phenol concentrations. The removal of phenol by the isolates was confirmed using Gas Chromatography. Through molecular techniques, Acinetobacter calcoaceticus K5 and Candida tropicalis YM2 were identified as the most efficient phenol-degrading strains. Acinetobacter calcoaceticus K5 exhibited the highest growth at phenol concentrations of 200 and 300 ppm, while Candida tropicalis YM2 showed optimal growth at a concentration of 700 pp. In case of Acinetobacter calcoaceticus, chitosan immobilization and a phenol concentration of 500 ppm proved to be the best conditions for phenol bioremediation. In the case of Candida tropicalis YM2, the highest percentage of phenol removal was achieved using the chitosan carrier at a concentration of 1000 ppm. Comparing the immobilized strains to their free counterparts, it was observed that the stabilized bacteria exhibited greater phenol removal efficiency, particularly at a concentration of 500 ppm, with a significant difference between the two conditions. This study demonstrates that the novel strains Acinetobacter calcoaceticus K5 and Candida tropicalis YM2 are efficient strains for the bioremediation of various phenol-contaminated seawater and this is the first report to show such rapid phenol degradation by these organisms isolated from sediment and seawater samples collected from Persian Gulf.

Species distribution and antifungal susceptibility profiles of yeasts isolated from onychomycosis: a cross-sectional study with insights into emerging species.

Candida onychomycosis is a common fungal infection affecting the nails, primarily caused by Candida (C.) species. Regarding the increasing trend of Candida onychomycosis and the antifungal resistant phenomenon in recent years, this study aims to evaluate the epidemiological characteristics of Candida onychomycosis, the distribution of emerging species, and the antifungal susceptibility profiles of isolates. Onychomycosis caused by yeast species was confirmed through direct examination and culture of nail scraping among all individuals suspected to have onychomycosis and referred to a medical mycology laboratory between June 2019 and March 2022. Species of yeast isolates were identified using the multiplex PCR and PCR-RFLP methods. The antifungal susceptibility of isolates to common antifungal agents and imidazole drugs was evaluated according to the M-27-A3 CLSI protocol. Among 101 yeast strains isolated from onychomycosis, Candida parapsilosis complex (50.49%) was the most common species, followed by C. albicans (20.79%) and C. tropicalis (10.89%). Rare species of yeasts such as C. guilliermondii and Saccharomyces cerevisiae were also identified by molecular methods. Results obtained from antifungal susceptibility testing showed significant differences in MIC values of isoconazole, fenticonazole, and sertaconazole among different species. Overall, a fluconazole-resistant rate of 3% was found among Candida species. Moreover, there was a statistically significant difference in MICs of fenticonazole and clotrimazole between the two most prevalent causative species, C. parapsilosis complex and C. albicans. Correct identification of the causative agents of onychomycosis and performing susceptibility testing could be helpful in choosing the most appropriate antifungal therapy.

Evaluation of the Effect of Some Plant Extracts as Antifungal Substances Isolated from Patients with Gingivitis and Endophthalmitis in Hilla City

During this study, 8 isolates of Candida yeast were isolated and diagnosed on CHROMagar, and Candida albicans was the most prevalent species by 75%. The inhibitory activity of plant extracts of adrak, cloves, green tea, and cinnamon was tested by disc diffusion test against C. albicans, C. krusei, and the antibiotics gentian stain, fluconazole, kenazole, nystatin were used for comparison. As well as using oral and dental cleaning products for comparison as well. The study showed that clove extract had a weak inhibitory activity at a high concentration, while extracts of green tea, cinnamon and mint did not show any activity in inhibiting C. albicans and showed that toothpaste had high activity in inhibiting yeast better than the plant extracts that did not show any inhibitory effect despite their use in high concentrations. We conclude from the current study that it is better to use toothpaste instead of herbs to get rid of gingivitis because it plays a major role in inhibiting Candida yeast.

Bioethanol Production from Decaying Oranges and Pineapple Juice Using Ethanol Tolerant-Yeast

Scientists across the globe ought to harness ways of getting alternative sources of energy which will be renewable, sustainable, efficient, eco-friendly, and cost effective because of the global energy crises owing to the cost of production, transportation and distribution of fossil fuel products. In Nigeria, decaying fruits always constitute a major environmental pollution during the harvesting season. This study screened, selected the best starter, and produced bioethanol from the juice obtained from decaying oranges and pineapple through the process of fermentation and distillation. Samples were collected from different locations within Ile-Ife and transported aseptically to the Laboratory. Microbiological and physicochemical assessment of the isolated strains were on yeast maintenance media. The cell biomass, pH, temperature, brix level, titratable acidity, specific gravity and ethanol yield were monitored during fermentation from day zero to day fourteen. Screening of the isolates obtained from a previous study was carried out to select the best starter for the production of bioethanol.
 S.cerevisae and K. marxianus and showed efficient physico-chemical attributes from the screening of the yeast isolates; a temperature of 30oC and pH 6 was the optimum for the growth of isolates tolerating 20% v/v absolute ethanol. Cultures were inoculated singly and in combination, S. cerevisiae gave the highest reduction in brix level from 2.2o at the onset and it reduced to 0.3o at the 21st day of fermentation while the least reduction was seen in K. marxianus. Mixed culture of S. cerevisiae and K. marxianus gave the highest reduction in brix level from 2.0o at the onset to 0.1o, pH reduced from 4.7- 3.3 while the cell biomass increased, and the temperature increased from 30oC to 34.5oC at the end of fermentation. Titratable acidity in the fermenting fruits juice increased from 0.23 to 1.76, the specific gravity reduced while the alcohol content increased from zero to 25.63 as the fermentation progressed and a reduction on day 21 (1.67) was observed.
 The use of decaying plant biomass or fruit waste can be a rich and cheaper source of substrate for different yeasts strains endogenous to the biomass for the production of environmental-friendly biofuel. This can also be employed as a waste management option and an alternative solution to environmental pollution and the global energy crises.

Selection of Starter from Decaying Oranges and Pineapple for Bioethanol Production

Screening of yeasts for bioethanol production is an important aspect of industrial microbiology and biotechnology. Optimal yeast nutrition also requires availability of nutrients allowing for growth and ethanol production and ability to withstand the increasing concentration of the medium during fermentation. This study seeks to use appropriate methods to isolate, characterize and identify yeasts isolates with essential attributes for bioethanol production. Microbiological and Physicochemical assessment of the isolated strains was carried out on yeast maintenance media for the determination of ethanol, temperature and salt tolerance ability, growth at different pH and temperature, chloramphenicol and nalidixic acid test, determination of killer toxins production capacity of yeast, nitrate and carbon assimilation and sugar fermentation tests were carried out to select the best starter for production.
 Fifteen yeasts were isolated belonging to the genera Saccharomyces, Candida, Rhodotorula, Kluvyreomyces, Trichosporon, Pichia. S. cerevisae and K. marxianus showed efficient physico-chemical attributes. Proximate analysis of fruits juice showed a moisture content between 81.83 – 86.37%, crude protein 1.33 – 2.00%, Ash 0.73 – 0.83%, carbohydrate 11.87 – 15.67% and Ether 0.1 – 0.5%. The total sugar ranged from 1.83 – 13.17, equal mixture of oranges and pineapple juice showed a sugar content of 15 which reduced during fermentation while the alcohol content increased. Organisms were able to tolerate a percentage of 4-30% ethanol content, tolerating 15% sodium chloride which is an index of osmotolerance. At higher concentration, growth reduced, organisms produced catalase, reduced nitrate and showed a variation in utilization of different sugars.
 At the end of the screening, S. cerevisiae and K. marxianus showed the best attribute essential for bioethanol production and were chosen as starters. The ability of the selected yeast isolates to produce Killer toxins against E. coli showed a negative result. Antibiotic sensitivity test was carried out on the selected yeast isolates using chloramphenicol and nalidixic and the two organisms were resistant to the antibiotics tested.
 The ability of the organisms to grow in changing environmental conditions and ethanol tolerance are attributes essential for production while Saccharomyces cerevisiae showed the highest attribute followed by Kluveromyces marxinus. This study concluded that Saccharomyces cerevisiae can be employed as starter in the industry for the production of bioethanol and in the conversion of agricultural waste to wealth.

Developing a novel selection method for alcoholic fermentation starters by exploring wine yeast microbiota from Greece.

The selection of native yeast for alcoholic fermentation in wine focuses on ensuring the success of the process and promoting the quality of the final product. The purpose of this study was firstly to create a large collection of new yeast isolates and categorize them based on their oenological potential. Additionally, the geographical distribution of the most dominant species, Saccharomyces cerevisiae, was further explored. Towards this direction, fourteen spontaneously fermented wines from different regions of Greece were collected for yeast typing. The yeast isolates were subjected in molecular analyses and identification at species level. RAPD (Random Amplified Polymorphic DNA) genomic fingerprinting with the oligo-nucleotide primer M13 was used, combined with Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) technique. All yeast isolates were scrutinized for their sensitivity to killer toxin, production of non-desirable metabolites such as acetic acid and H2S, β-glucosidase production and resistance to the antimicrobial agent; SO2. In parallel, S. cerevisiae isolates were typed at strain level by interdelta - PCR genomic fingerprinting. S. cerevisiae strains were examined for their fermentative capacity in laboratory scale fermentation on pasteurized grape must. Glucose and fructose consumption was monitored daily and at the final point a free sorting task was conducted to categorize the samples according to their organoleptic profile. According to our results, among the 190 isolates, S. cerevisiae was the most dominant species while some less common non-Saccharomyces species such as Trigonopsis californica, Priceomyces carsonii, Zygosaccharomyces bailii, Brettanomyces bruxellensis and Pichia manshurica were identified in minor abundancies. According to phenotypic typing, most isolates were neutral to killer toxin test and exhibited low acetic acid production. Hierarchical Cluster Analysis revealed the presence of four yeast groups based on phenotypic fingerprinting. Strain level typing reported 20 different S. cerevisiae strains from which 65% indicated fermentative capacity and led to dry wines. Sensory evaluation results clearly discriminated the produced wines and consequently, the proposed yeast categorization was confirmed. A novel approach that employs biostatistical tools for a rapid screening and classification of indigenous wine yeasts with oenological potential, allowing a more efficient preliminary selection or rejection of isolates is proposed.

Bio-Ethanol Production from Wheat Straw Using Yeast Isolates

In the first hand, the cost of fossil fuel is increasing alarmingly. On the second hand, combustion of fossil fuels contributes for global warming. Therefore, it need to strength the production of renewable energies. The aim of this study was to produce bioethanol from wheat straw using yeast isolates. The isolates were isolated from decomposed soil, termite soil and rotten wood samples using yeast extract peptone dextrose media (YPD) and characterized chemically and morphologically. The wheat straws were powdered and hydrolyzed with dilute sulfuric acids. After neutralization, it was used to produce ethanol. Response surface methodology was employed to optimize the ethanol production process from wheat straws. The isolates were grown optimally at a temperature of 30oC, pH nearly 5, and sugar concentration 70 to 120 g/L. Among hydrolysis conditions, lower acid concentration (less than 1.5%) and temperature of 60oC resulted higher reducing sugars. The optimization study showed that the highest bio-ethanol concentration of 6.8g/l was observed by SWX under the optimum conditions of with 1% H2S04, 60oC temperature and 52.5-minute time hydrolysis at 30°C for 48 hour incubation time. Wheat straws could be good candidate for ethanol production.

Microbial communities of a variety of 75 homemade fermented vegetables.

Fermentation is an ancient practice of food preservation. Fermented vegetables are popular in Eastern European and Asian countries. They have received a growing interest in Western countries, where they are mainly manufactured at domestic and artisanal scales and poorly characterized. Our aim was to investigate the microbial communities and the safety of French homemade fermented vegetables, in the frame of a citizen science project. Fermented vegetables and the data associated with their manufacture were collected from citizens and characterized for pH, NaCl concentration, and microbiology by culturomics and 16S DNA metabarcoding analysis. Lactic acid bacteria (LAB) and yeast isolates were identified by 16S rRNA gene sequencing and D1/D2 domains of the large subunit of the rRNA gene, respectively. The 75 collected samples contained 23 types of vegetables, mainly cabbage, followed by carrots and beets, and many mixtures of vegetables. They were 2 weeks to 4 years old, and their median pH was 3.56, except for two samples with a pH over 4.5. LAB represented the dominant viable bacteria. LAB concentrations ranged from non-detectable values to 8.7 log colony-forming units (CFU)/g and only depended on the age of the samples, with the highest most frequently observed in the youngest samples (<100 days). The 93 LAB isolates identified belonged to 23 species, the two mains being Lactiplantibacillus pentosus/plantarum and Levilactobacillus brevis. The other microbial groups enumerated (total aerobic bacteria, halotolerant bacteria, Gram-negative bacteria, and acetic acid bacteria) generally showed lower concentrations compared to LAB concentrations. No pathogenic bacteria were detected. Viable yeasts were observed in nearly half the samples, at concentrations reaching up to 8.0 log CFU/g. The 33 yeast clones identified belonged to 16 species. Bacterial metabarcoding showed two main orders, namely, Lactobacillales (i.e., LAB, 79% of abundance, 177 of the 398 total ASVs) and Enterobacterales (19% of abundance, 191 ASVs). Fifteen LAB genera were identified, with Lactiplantibacillus and Levilactobacillus as the most abundant, with 41 and 12% of total reads, respectively. Enterobacterales members were mainly represented by Enterobacteriaceae and Yersiniaceae. This study is the first wide description of the microbiota of a large variety of homemade fermented vegetables and documents their safety.

Enhancement of novel Endo-polygalacturonase expression in Rhodotorula mucilaginosa PY18: insights from mutagenesis and molecular docking

Pectinase is a particular type of enzyme that can break down pectin compounds and is extensively utilised in the agricultural field. In this study, twenty yeast isolates were isolated and assayed for pectinase activity. Molecular identification by PCR amplification and sequencing of internal transcribed spacer (ITS) regions of isolate no. 18 had the highest pectinase activity of 46.35 U/mg, was identified as Rhodotorula mucilaginosa PY18, and was submitted under accession no. (OM275426) in NCBI. Rhodotorula mucilaginosa PY18 was further enhanced through sequential mutagenesis, resulting in a mutant designated as Rhodotorula mucilaginosa E54 with a specific activity of 114.2 U/mg. Using Response Surface Methodology (RSM), the best culture conditions for the pectinase-producing yeast mutant Rhodotorula mucilaginosa E54 were pH 5, 72-h incubation, 2.5% xylose, and 2.5% malt extract, with a pectinase-specific activity of 156.55 U/mg. Then, the obtained sequences of the endo-polygalacturonase PGI gene from Rhodotorula mucilaginosa PY18 and mutant Rhodotorula mucilaginosa E54 were isolated for the first time, sequenced, and submitted to NCBI accession numbers OQ283005 and OQ283006, respectively. The modelled 3D structure of the endo-PGI enzyme (485 residues) was validated using Ramachandran’s plot, which showed 87.71, 85.56, and 91.57% in the most favourable region for template Rhodotorula mucilaginosa KR, strain Rhodotorula mucilaginosa PY18, and mutant Rhodotorula mucilaginosa E54, respectively. In molecular docking studies, the results of template Rhodotorula mucilaginosa KR endo-PG1 showed an interaction with an affinity score of − 6.0, − 5.9, and − 5.6 kcal/mol for active sites 1, 2, and 3, respectively. Rhodotorula mucilaginosa PY18 endo-PG1 showed an interaction affinity with a score of − 5.8, − 6.0, and − 5.0 kcal/mol for active sites 1, 2, and 3, respectively. Mutant Rhodotorula mucilaginosa E54 endo-PG1 showed an interaction affinity of − 5.6, − 5.5, – 5.5 and − 5.4 kcal/mol for active sites 1, 2, and 3, respectively. The endo-PGI genes of both the yeast strain Rhodotorula mucilaginosa PY18 and mutant Rhodotorula mucilaginosa E54 were successfully cloned and expressed in E. coli DH5α, showing significantly higher endo-PG1 activity, which recorded 94.57 and 153.10 U/mg for recombinant Rhodotorula mucilaginosa pGEM-PGI-PY18 and recombinant mutant Rhotorula pGEM-PGI-E54, respectively.

Effect of Alcoholic Extract of Syntrichia intermedia on some Yeasts Isolated from Mobile Phones and the User’s Finger

Syntrichia intermedia was isolated from the Amadiya region in northern Iraq for the first time, as it was used against the yeast Brettanomyces bruxellensis, Candida krusei and the yeast Meyerozyma caribbica isolated fore the first one and registered as a new strain in the Gen Bank of the National Center for Biotechnology Information (NCBI) with identification number LC723825.1. Three methods were used to determine the effect of the alcoholic extract of S. intermedia at the following concentrations, 1, 2, 4, 6, 8, and 10 mg/ml against yeast isolates, When using the first method-turbidity measurement the concentrations were shown starting from 1 mg/ml an inhibitory effect respectively up to the highest concentration of 10 mg/ml against yeast B. bruxellensis, C. krusei and M. caribbica. and When using the second method-disc diffusion the following concentration showed the highest inhibition percentage the concentration of 2 mg / ml with a diameter of (12.50 mm) against the yeast B. bruxellensis. and The concentrations 1 with a diameter of (11.0 mm) against the yeast C. krusei and The concentrations 4 mg / ml with a diameter of (11.50 mm) Compared with the antibiotic Nystatin which showed a higher percentage of inhibition than the alcoholic extract, While the third method-diffusion by wells was used and the concentration of 4 mg / ml showed the highest percentage of inhibition with a diameter of (23.0 mm) for yeast B. bruxellensis and a concentration of 6 mg / ml showed the highest percentage of inhibition with a diameter of (19.00 mm) against yeast C. krusei. and a concentration of 8 mg / ml showed the highest percentage of inhibition with a diameter of (15.67 mm) against yeast M. caribbica compared with the antibiotic Nystatin, which showed less inhibition than the alcoholic extract, so the yeast B. bruxellensis was more sensitive to the alcoholic extract, followed by the yeast M. caribbica. Then the yeast When using the method of diffusion by discs and digging, either by measuring the turbidity the yeast M. caribbica was the most sensitive to the alcoholic extract followed by C. krusei Then the yeast B. bruxellensis, so the turbidity measurement method is considered one of the best methods that can be used to measure the effect of the alcoholic extract because of measuring the turbidity using a spectrophotometer, followed by the diffusion method by wells, then the method of diffusion by discs.

Influence of Yeast Bioinoculant Isolated from Indian Date Palm Tree (Phoenix sylvestris) Sap on the Health of Wheat Crop and Soil

In this study, three promising yeast isolates were isolated from the sap of the Indian date palm tree (Phoenix sylvestris) and characterized by biochemical tests and 18S rRNA gene sequencing. They were confirmed as Saccharomyces cerevisiae and were designated as strains PYS-1, PYS-2, and PYS-3. These confirmed strains were used for the preparation of bioinoculants. Bioinoculant was prepared and applied to wheat crops, and the effect of Bioinoculant. Statistical analysis is carried out using analysis of variance (ANOVA), and it is found that the absorbance of chlorophyll, protein, and Indole Acetic Acid (IAA) content is significantly increased. The treatment of bioinoculant showed that crops significantly increased chlorophyll, protein, and IAA content. Further, we applied bioinoculant on the soil and measured the soil’s humus content before and after the treatment of bioinoculant. Then, a paired t-test was applied to check the effectiveness of the treatment, and it was found to significantly increase humus content in the soil. The use of bioinoculants is an economically feasible and eco-friendly method.

Snapshot of the Probiotic Potential of Kluveromyces marxianus DMKU-1042 Using a Comparative Probiogenomics Approach.

Kluyveromyces marxianus is a rapidly growing thermotolerant yeast that secretes a variety of lytic enzymes, utilizes different sugars, and produces ethanol. The probiotic potential of this yeast has not been well explored. To evaluate its probiotic potential, the yeast strain Kluyveromyces marxianus DMKU3-1042 was analyzed using next-generation sequencing technology. Analysis of the genomes showed that the yeast isolates had a GC content of 40.10-40.59%. The isolates had many genes related to glycerol and mannose metabolism, as well as genes for acetoin and butanediol metabolism, acetolactate synthase subunits, and lactic acid fermentation. The strain isolates were also found to possess genes for the synthesis of different vitamins and Coenzyme A. Genes related to heat and hyperosmotic shock tolerance, as well as protection against reactive oxygen species were also found. Additionally, the isolates contained genes for the synthesis of lysine, threonine, methionine, and cysteine, as well as genes with anticoagulation and anti-inflammatory properties. Based on our analysis, we concluded that the strain DMKU3-1042 possesses probiotic properties that make it suitable for use in food and feed supplementation.

Isolation and Screening Microorganisms from Black Soldier Fly Larvae (Hermetia illucens) that Producing Amylase, Protease and Cellulase

The Black Soldier Fly (BSF) has gained significant attention for its ability to decompose various types of organic waste and produce valuable enzymes related to its digestive system. These enzymes hold immense potential for applications across diverse industrial sectors, with promise in the livestock industry. This study aimed to extract and assess amylase, protease, and cellulase enzymes from microorganisms present in BSF larvae fermentation. The isolation technique employed was the spread plate method, followed by rigorous screening for the presence of these enzymes. The results showed 46 isolates of 26 bacterial isolates and 20 yeast isolates. In the amylase enzyme screening, a substantial 25 bacterial and 19 yeast isolates exhibited positive amylase activity. For cellulase, 20 bacterial and 14 yeast isolates displayed positive results. In the case of protease, 16 bacterial and 12 yeast isolates demonstrated protease enzyme activity. Notably, nine isolates exhibited the remarkable capability to produce multiple enzymes, including eight bacterial and one yeast isolate. These results showcase the rich enzymatic potential of BSF-associated microorganisms, offering exciting prospects for their application in various industrial sectors, especially in enhancing the efficiency and sustainability of livestock production

Fungal communities and their correlation with the sensory quality of rice wine from the Xiaogan and Dazhou regions in China

In this study, we performed a comparative analysis of fungal communities and cultivable yeast isolates in rice wine from the Xiaogan and Dazhou regions using Illumina MiSeq high-throughput sequencing technology and traditional culture-dependent methods. And we further explored the correlation between the sensory quality and fungal communities in rice wine. The results demonstrated no significant difference (P > 0.05) in the abundance and diversity of fungal communities and cultivable yeast isolates between Xiaogan and Dazhou rice wine. The dominant fungal genera were Rhizopus and Saccharomyces, with Saccharomyces cerevisiae accounting for the greatest proportion of yeast isolates. The rice wine samples could be divided into two types based on the composition of fungal communities. Type 1 mainly contained Rhizopus and Saccharomyces, while type 2 mainly contained Rhizopus. Properties such as lightness, blueness-yellowness, methane levels, ethanol levels, organic sulfide content, and soluble solids content accounted for the main differences between the two types of rice wine. In addition, Candida and Clavispora showed a significant positive correlation (P < 0.05) with the aromatic substances in rice wine. The findings of the study enrich our understanding of traditional rice wine, providing meaningful information for the improvement and development of the traditional rice wine industry.

Sustainable production of bioethanol from office paper waste and its purification via blended polymeric membrane

One potential replacement for fossil fuels is the generation of biofuel from biomass feedstock. To reach the global sustainability goals, it is also necessary to address a number of issues, such as reducing environmental pollution, climate change, and carbon emissions. This work was aimed to convert the office paper waste as biomass feedstock into bioethanol through a sustainable pathway. The office paper waste was hydrolyzed via physiochemical and enzymatic hydrolysis, the liberated glucose was estimated at 15.72 g/L using the optimum conditions of 15 % HCl and 6 % office paper waste followed by enzymatic hydrolysis. The yeast isolate B2 that was applied for the fermentation process was isolated from rotten banana, identified as Hanseniaspora uvarum (STDF-B2) and submitted to GenBank with accession number (OP800106). The Box-Behnken design was applied to estimate the optimal conditions for the three most significant variables depending on the one variable at a time results. A blended membrane of sulphonated polyvinyl chloride with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (SPVC-PAMPS) was applied for the purification of both standard ethanol and produced bioethanol via pervaporation technique (PV). The morphology, chemical composition, mechanical properties and permeability of the membrane were all analyzed in various ways. Following purification using a membrane-integrated amicon cell, the total permeate flows of the laboratory-prepared ethanol and generated bioethanol were 289.54 and 253.06 (g/m2 h), respectively.

Tannin-Tolerant Saccharomyces cerevisiae Isolated from Traditional Fermented Tea (Miang) of Northern Thailand and Its Feasible Applications

This study evaluated the ability of a yeast strain isolated from traditional fermented tea leaves (Camellia sinensis var. assamica), Miang from northern Thailand, to grow and produce ethanol in the presence of tannin. Among 43 Miang samples, 25 yeast isolates displayed gas-forming character in the presence of 1% (w/v) tannin, but only ML1-1 and ML1-2 isolates were confirmed as ethanol-producing yeast capable of tannin tolerance. These isolates were further identified to be Pichia occidentalis and Saccharomyces cerevisiae, respectively, based on D1/D2 domain sequence analysis. S. cerevisiae ML1-2 was selected for further studies and exhibited growth at 20–35 °C, pH 4–7, and tolerance to high sugar concentrations of up to 350 g/L. Supplementation of 1% (w/v) tannin had no effect on sugar utilization and ethanol production, while delayed sugar consumption and ethanol production were observed in the reference strain S. cerevisiae TISTR 5088. However, 5 and 10% (w/v) tannin showed inhibitory effects on the growth and ethanol production of the selected yeast isolates. During the fermentation under high tannin conditions derived by mixing Java plum fruit with ground seed, S. cerevisiae ML1-2 showed significant advantages in growth and enhanced the content of ethanol, polyphenols, tannin, and flavonoids compared to S. cerevisiae TISTR 5088. This indicated its potential for high-tannin substrate-based bioconversion for the production of either fuel ethanol or functional alcoholic beverages.

Potential of endophytic yeasts as biocontrol of Phytophthora capsici, causative agent of foot rot disease on black pepper

Abstract. Safitri D, Wiyono S, Purbajanti ED. 2023. Potential of endophytic yeasts as biocontrol of Phytophthora capsici, causative agent of foot rot disease on black pepper. Biodiversitas 24: 5847-5853. Phytophthora capsici is the main pathogen of foot rot disease of black pepper. This disease contributes to a significant decrease in black pepper productivity. Conventional disease management strategies usually require the use of chemical pesticides, which can have harmful environmental and human health consequences. Introducing biological agents such as endophytic yeasts for controlling foot rot disease has minimal effect on human health and is sustainable. One technique to control foot rot disease is to use biological agents such as endophytic yeasts. The aim of this research was to find yeast against Phytophthora capsici. The methods used included (i) study development and identification of endophytic yeast and (ii) in vitro and in vivo antagonism screening of yeast against P. capsici. The results showed that 49 endophytic yeasts were isolated from the leaves, fruits and roots of three black pepper lines. Five isolates had selected based on the highest antibiosis in antagonism test by in vitro: END6, END21, END66, END87, and END14. Isolate END87 had a mycelium inhibition rate of 64.55%, and a low level of inhibition was found in isolate 21, which had a mycelium size of 42.81%. The molecular characterization based on the sequence partial of NL1 and NL4. Moreover, 5 isolates of endophytic yeast (END6, END21, END66, END87, and END14) were identified as Rhodotorula mucilaginosa, Hannaella oryzae, Cryptococcus tephrensis.

Effect of Adding Probiotic Yeast and Fermentation Time on Probiotic Tempeh Characteristics

Tempeh is one of the foods made from soybean seeds or other ingredients that are processed through fermentation. Tempeh currently circulating in the community does not contain probiotic yeast, the addition of probiotic yeast is intended to provide probiotic properties to tempeh. From previous studies, yeast isolates from radishes and tomatoes have been identified as potential probiotic yeasts. This study aimed to determine the effect of adding the type of probiotic yeast isolate and fermentation time on the number of fungi, the number of yeasts, pH, antioxidant activity, and the level of preference by panelists for the resulting probiotic tempeh. This study used a completely randomized design with a factorial pattern. The first factor was the type of probiotic inoculum (Saccharomyces boulardii, yeast isolate LBK K, yeast isolate TMT 2), and the second factor was incubation time (0 hours, 24 hours, and 48 hours). The analysis included the number of fungus and yeast (plate count agar), antioxidant activity (radical scavenging activity (%), and preference level for probiotic tempeh. The data obtained were analyzed for variance (ANOVA) at a 95% confidence level. If there was a significant difference between each treatment was continued with Duncan's multiple range test (DMRT). The results showed that adding probiotic yeast type and a long incubation time affected the microbiological properties, antioxidant activity, and panelist preference. The most preferred tempeh was tempeh with the addition of LBK K isolate with an incubation time of 48 hours with a pH of 5.46, the total number of fungi was 6.62 log CFU/g, the total amount of yeast was 8,63 log CFU/g, the antioxidant activity was 18.58% RSA. Tempeh, with the addition of LBK K yeast isolate, has the potential as a probiotic food.

Bioethanol Production from Non-Conventional Yeasts Wickerhamomyces anomalus (Pichia anomala) and Detection of ADH1 Gene

Bioethanol is an organic compound resulted from the fermentation of sugar substrates by microorganisms which is used as alternative energy sources. During bioethanol fermentation yeast are exposed to various fermentation stresses, including temperature, osmotic, and oxidative stresess. Such conditions may decrease ethanol production. We previously isolated fermentation-stress tolerance yeast isolates from traditional Balinese beverages, identified as Wickerhamomyces anomalus BT2, BT5, and BT6. However no data available regarding the bioethanol production of those isolates. Our study indicates that these strains could utilize various sugar substrates (glucose, xylose, maltose, sucrose) in oxidative fermentative media. The highest value of substrate utilization efficiency following 48 hours fermentation was shown by BT6 on glucose (61.02%), BT 2 on xylose (55.44%) and maltose (60.90%). Measurement of ethanol production by Gas Chromatography showed that the strains were able to produce higher ethanol on the glucose substrate than other substrates. For instance, BT6 could produce the highest ethanol production (5.00 g/L) amongst strains tested by using glucose as substrate. Yet, the particular strains could only produce 0.30 g/L and 0.65 g/L by using xylose and maltose, respectively. For further genetic engineering purposes, we detected ADH1 gene from all three isolates, with high homology to the alcohol dehydrogenase from Saccharomyces cerevisiae, Geobacillus stearothermophilus and Pseudomonas aeruginosa. Further strain development can be carried out targeting the ADH1 gene, important for ethanol fermentation.