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Colloids and Surfaces. B, Biointerfaces May 2023In this research, CuZnSnS (CZTS) particles were successfully fabricated via the molten salt approach from the copper, zinc and tin sulphides as raw precursors. SEM...
In this research, CuZnSnS (CZTS) particles were successfully fabricated via the molten salt approach from the copper, zinc and tin sulphides as raw precursors. SEM analysis revealed that CZTS particles are tetragonal-shaped with sharp edges, smooth flat plane morphology, and crystal size varying from 10.8 to 28.7 µm. The phase and crystalline structure of synthesized powders were investigated using XRD analysis, which confirms the presence of a tetragonal crystal structure kesterite phase. The chemical composition of CZTS particles was evaluated by EDX spectroscopy, which identified the nearly stoichiometric composition with an averaged formula of CuZnSnS. The TG/DTA-MS and ICP-OES analysis showed the possible decomposition pathways and predicted their degradation rate in aqueous solutions. The CZTS particles possessed highly effective concentration and time-dependent antimicrobial properties against medically relevant bacteria and yeast strains. The CZTS particles (1 g L) exhibited over 95.7 ± 1.9% killing efficiency towards M. luteus. In contrast, higher dosages (3.5 and 5 g L) led to its complete inactivation and reduced the P. aeruginosa cell viability to 43.2 ± 3.2% and 4.1 ± 1.1%, respectively. Moreover, the CZTS particles (0.5 g L) are responsible for causing 54.8 ± 1.8% of C. krusei and 89.7 ± 2.1% of C. parapsilosis yeasts death within the 24 h of exposure, which expanded to almost 100% when yeasts were treated with two times higher CZTS concentration (1.0 g L). The mechanism of action has been proposed and evidenced by monitoring the 2',7'-dichlorofluorescein (DCF) fluorescence, which revealed that the overproduction of reactive oxygen species (ROS) is responsible for microorganism death.
Topics: Anti-Infective Agents; Candida parapsilosis; Cell Survival; Copper; Pseudomonas aeruginosa; Saccharomyces cerevisiae
PubMed: 36965333
DOI: 10.1016/j.colsurfb.2023.113275 -
Biotechnology For Biofuels 2020Although bioethanol production has been gaining worldwide attention as an alternative to fossil fuel, ethanol productivities and yields are still limited due to the...
BACKGROUND
Although bioethanol production has been gaining worldwide attention as an alternative to fossil fuel, ethanol productivities and yields are still limited due to the susceptibility of fermentation microorganisms to various stress and inhibitory substances. There is therefore an unmet need to search for multi-stress-tolerant organisms to improve ethanol productivity and reduce production cost, particularly when lignocellulosic hydrolysates are used as the feedstock.
RESULTS
Here, we have characterized a previously isolated LC375240 strain which is thermotolerant to high temperatures of 37 °C and 42 °C. More excitingly, growth and ethanol productivity of this strain exhibit strong tolerance to multiple stresses such as acetic acid, furfural, formic acid, HO and high concentration of ethanol at 42 °C. In addition, simple immobilization of LC375240 on corncobs resulted to a more stable and higher efficient ethanol production for successive four cycles of repeated batch fermentation at 42 °C.
CONCLUSION
The feature of being thermotolerant and multi-stress-tolerant is unique to LC375240 and makes it a good candidate for second-generation bioethanol fermentation as well as for investigating the molecular basis underlying the robust stress tolerance. Immobilization of LC375240 on corncobs is another option for cheap and high ethanol productivity.
PubMed: 32477425
DOI: 10.1186/s13068-020-01729-5 -
Archives of Microbiology Sep 2021Soil yeasts exhibit an array of beneficial effects to plants viz., plant growth promotion, phosphate solubilization, nitrogen and sulphur oxidation, etc. Yeasts remain...
Soil yeasts exhibit an array of beneficial effects to plants viz., plant growth promotion, phosphate solubilization, nitrogen and sulphur oxidation, etc. Yeasts remain as poorly investigated group of microorganisms that represent an abundant and dependable source of bioactive/chemically novel compounds and potential bioinoculants. Hence this study holds the key concept of assessing the performance of soil yeasts with potential plant growth promoting ability in soil quality improvement. Sixteen soil yeast isolates with plant growth promoting traits were assessed for biofilm forming potential and five potential soil yeast isolates were selected and identified through molecular technique. Soil incubation study was performed with these isolates to assess their impact on soil physical, chemical and biological properties. Due to inoculation of soil yeasts, notable changes were observed in soil physical, chemical and biological properties. Among the soil yeast isolates, Pichia kudriavzevii gave better results in soil incubation study.
Topics: Pichia; Soil; Soil Microbiology
PubMed: 34165623
DOI: 10.1007/s00203-021-02447-8 -
Journal of Fungi (Basel, Switzerland) Dec 2021Improving the comprehensive utilization of sugars in lignocellulosic biomass is a major challenge for enhancing the economic viability of lignocellulose biorefinement. A...
Improving the comprehensive utilization of sugars in lignocellulosic biomass is a major challenge for enhancing the economic viability of lignocellulose biorefinement. A robust yeast N-X showed excellent performance in ethanol production under high temperature and low pH conditions and was engineered for ᴅ-xylonate production without xylitol generation. The recombinant strain N-X/S1 was employed for sequential production of ᴅ-xylonate and ethanol from ᴅ-xylose, feeding on ᴅ-glucose without pH control in a two-stage strategy of aerobic and shifting micro-aerobic fermentation. Acid-pretreated corncob without detoxification and filtration was used for ᴅ-xylonate production, then simultaneous saccharification and ethanol fermentation was performed with cellulase added at pH 4.0 and at 40 °C. By this strategy, 33.5 g/L ᴅ-xylonate and 20.8 g/L ethanol were produced at yields of 1.10 g/g ᴅ-xylose and 84.3% of theoretical value, respectively. We propose a promising approach for the sequential production of ᴅ-xylonate and ethanol from non-detoxified corncob using a single microorganism.
PubMed: 34947020
DOI: 10.3390/jof7121038 -
International Journal of Food... Dec 2016Together with acidifying lactic acid bacteria, yeasts play a key role in the production process of sourdough, where they are either naturally present or added as a... (Review)
Review
Together with acidifying lactic acid bacteria, yeasts play a key role in the production process of sourdough, where they are either naturally present or added as a starter culture. Worldwide, a diversity of yeast species is encountered, with Saccharomyces cerevisiae, Candida humilis, Kazachstania exigua, Pichia kudriavzevii, Wickerhamomyces anomalus, and Torulaspora delbrueckii among the most common ones. Sourdough-adapted yeasts are able to withstand the stress conditions encountered during their growth, including nutrient starvation as well as the effects of acidic, oxidative, thermal, and osmotic stresses. From a technological point of view, their metabolism primarily contributes to the leavening and flavour of sourdough products. Besides ethanol and carbon dioxide, yeasts can produce metabolites that specifically affect flavour, such as organic acids, diacetyl, higher alcohols from branched-chain amino acids, and esters derived thereof. Additionally, several yeast strains possess functional properties that can potentially lead to nutritional and safety advantages. These properties encompass the production of vitamins, an improvement of the bioavailability of phenolic compounds, the dephosphorylation of phytic acid, the presence of probiotic potential, and the inhibition of fungi and their mycotoxin production. Strains of diverse species are new candidate functional starter cultures, offering opportunities beyond the conventional use of baker's yeast.
Topics: Amino Acids, Branched-Chain; Biodiversity; Bread; Candida; Carbon Dioxide; Ethanol; Fermentation; Food Microbiology; Lactobacillaceae; Saccharomyces cerevisiae; Yeast, Dried
PubMed: 27470533
DOI: 10.1016/j.ijfoodmicro.2016.07.018 -
Frontiers in Microbiology 2022To explore the potential application of non- yeasts screened from Baijiu fermentation environment in winemaking, the effect of four Baijiu non- yeasts (two and two )...
To explore the potential application of non- yeasts screened from Baijiu fermentation environment in winemaking, the effect of four Baijiu non- yeasts (two and two ) sequentially fermented with on the physicochemical parameters and volatile compounds of wine was analyzed. The results indicated that there was no obvious antagonism between and or in sequential fermentations, and all strains could be detected at the end of alcoholic fermentation. Compare with pure fermentation, sequential fermentations significantly reduced higher alcohols, fatty acids, and ethyl esters and increased acetate esters; sequential fermentations reduced the contents of C6 alcohols, total higher alcohols, fatty acids, and ethyl esters and significantly increased the contents of acetate esters (especially ethyl acetate and 3-methylbutyl acetate). Sequential fermentation of Baijiu non- yeast and improved the flavor and quality of wine due to the higher ester content and lower concentration of higher alcohols and fatty acids, non- yeasts selected from Baijiu fermentation environment have potential applications in winemaking, which could provide a new strategy to improve wine flavor and quality.
PubMed: 35711782
DOI: 10.3389/fmicb.2022.902597 -
Microorganisms Apr 2023There is an expanding market for beer of different flavors. This study aimed to prepare a craft Belgian-style pale ale with a non- yeast. 4A was used as a sole starter...
There is an expanding market for beer of different flavors. This study aimed to prepare a craft Belgian-style pale ale with a non- yeast. 4A was used as a sole starter culture, and malted barley as the only substrate. The ingredients and brewing process were carefully monitored to ensure the quality and innocuousness of the beverage. During fermentation, the yeast consumed 89.7% of total sugars and produced 13.8% / of ethanol. The product was fermented and then aged for 8 days, adjusted to 5% / alcohol, and analyzed. There were no traces of mycotoxins, lead, arsenic, methanol, or microbiological contamination that would compromise consumer health. According to the physicochemical analysis, the final ethanol concentration (5.2% /) and other characteristics complied with national and international guidelines. The ethyl acetate and isoamyl alcohol present are known to confer sweet and fruity flavors. The sensory test defined the beverage as refreshing and as having an apple and pear flavor, a banana aroma, and a good level of bitterness. The judges preferred it over a commercial reference sample of Belgian-style pale ale made from . Hence, 4A has the potential for use in the beer industry.
PubMed: 37110400
DOI: 10.3390/microorganisms11040977 -
Microbial Biotechnology May 2021The unconventional yeast Pichia kudriavzevii is renowned for its ability to survive at low pH and has been exploited for the industrial production of various organic...
The unconventional yeast Pichia kudriavzevii is renowned for its ability to survive at low pH and has been exploited for the industrial production of various organic acids, especially succinic acid (SA). However, P. kudriavzevii can also utilize the di- and tricarboxylate intermediates of the Krebs cycle as the sole carbon sources for cell growth, which may adversely affect the extracellular accumulation of SA. Because the carboxylic acid transport machinery of P. kudriavzevii remains poorly understood, here, we focused on studying its SA transportation process from the perspective of mining and characterization of dicarboxylate transporters in a newly isolated acid-tolerant P. kudriavzevii strain CY902. Through genome sequencing and transcriptome analysis, two JEN family carboxylate transporters (PkJEN2-1 and PkJEN2-2) were found to be involved in SA transport. Substrate specificity analysis revealed that both PkJEN proteins are active dicarboxylate transporters, that can effectively import succinate, fumarate and L-malate into the cell. In addition, PkJEN2-1 can transport α-ketoglutarate, while PkJEN2-2 cannot. Since PkJEN2-1 shows higher transcript abundance than PkJEN2-2, its role in dicarboxylate transport is more important than PkJEN2-2. In addition, PKJEN2-2 is also responsible for the uptake of citrate. To our best knowledge, this is the first study to show that a JEN2 subfamily transporter is involved in tricarboxylate transport in yeast. A combination of model-based structure analysis and rational mutagenesis further proved that amino acid residues 392-403 of the tenth transmembrane span (TMS-X) of PkJEN2-2 play an important role in determining the specificity of the tricarboxylate substrate. Moreover, these two PkJEN transporters only exhibited inward transport activity for SA, and simultaneous inactivation of both PkJEN transporters reduced the SA influx, resulting in enhanced extracellular accumulation of SA in the late stage of fermentation. This work provides useful information on the mechanism of di-/tricarboxylic acid utilization in P. kudriavzevii, which will help improve the organic acid production performance of this microbial chassis.
Topics: Membrane Transport Proteins; Pichia; Saccharomyces cerevisiae; Succinates; Succinic Acid
PubMed: 33629807
DOI: 10.1111/1751-7915.13781 -
Journal of Fungi (Basel, Switzerland) Oct 2022The aim of this study was to investigate the effects of purified β-glucosidases from SLY-4, F2-24, and HX-13 (named as SLY-4E, F2-24E, and HX-13E, respectively) on...
The aim of this study was to investigate the effects of purified β-glucosidases from SLY-4, F2-24, and HX-13 (named as SLY-4E, F2-24E, and HX-13E, respectively) on the flavor complexity and typicality of wines. Cabernet Sauvignon wines were fermented by with the addition of SLY-4E, F2-24E, and HX-13E; the fermentation process and characteristics of wines were analyzed. The addition of SLY-4E, F2-24E, and HX-13E into must improved the contents of terpenes, higher alcohols, and esters, and decreased the contents of C compounds and fatty acids, which enhanced the fruity, floral, and taste aspects, reducing the unpleasant green of wines with no significant difference in their appearance. β-glucosidases from different yeast species produced different aroma compound profiles which presented different flavor and quality. F2-24EW had the best effect on flavor and quality of wine followed by SLY-4EW and HX-13EW. These research results can provide references for the use of β-glucosidases from non- yeasts to improve the flavor complexity, typicality, and quality of wines.
PubMed: 36294622
DOI: 10.3390/jof8101057 -
Journal of Medical Microbiology Dec 2017Fungaemia is associated with substantial morbidity and mortality in neonates admitted to neonatal intensive care units (NICUs). We report an outbreak of fungaemia in a...
PURPOSE
Fungaemia is associated with substantial morbidity and mortality in neonates admitted to neonatal intensive care units (NICUs). We report an outbreak of fungaemia in a NICU due to rare yeast, Pichia kudriavzevii (a teleomorph of Candida krusei). To the best of our knowledge, this is the first report of neonatal sepsis due to P. kudriavzevii.
METHODOLOGY
Between August and September 2014, blood cultures from nine neonates diagnosed with late-onset sepsis in the NICU yielded yeast-like organisms. The molecular identification and typing of these isolates was performed by sequencing the D1/D2 region of 26S rDNA and fluorescent amplified fragment length polymorphism (FAFLP) respectively. Antifungal susceptibility was tested by broth microdilution as per the Clinical Laboratory Standards Institute (CLSI) guidelines. Sampling from environmental sources and the hands of healthcare workers (HCWs) in the NICU was performed.
RESULTS
Of the nine neonates, eight were preterm and six had very low birth weight (VLBW). Thrombocytopenia was present in two neonates. Sequencing identified all the isolates as P. kudriavzevii and FAFLP showed their clonal origin. Antifungal susceptibility testing revealed the susceptibility of all isolates to the antifungals tested. Treatment with voriconazole was advised. However, only seven neonates were treated successfully and discharged after improvement, whereas two were lost for follow-up. Cultures from the environment and the hands of HCWs were negative. The outbreak was controlled by the strict implementation of infection control practices.
CONCLUSION
This study emphasizes the importance of accurate identification of the aetiological agent of sepsis and vigilant monitoring for the possibility of an outbreak in NICUs.
Topics: Amplified Fragment Length Polymorphism Analysis; Antifungal Agents; DNA, Fungal; Disease Outbreaks; Drug Resistance, Multiple, Fungal; Female; Fungemia; Humans; Infant; Infant, Premature; Infant, Very Low Birth Weight; Infection Control; Intensive Care Units, Neonatal; Male; Microbial Sensitivity Tests; Morbidity; Pichia; Thrombocytopenia; Voriconazole
PubMed: 29134932
DOI: 10.1099/jmm.0.000645