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Microbiology Spectrum Jan 2024is a promising industrial chassis to produce biofuels and bioproducts due to its high tolerance to multiple environmental stresses such as low pH, heat, and other...
is a promising industrial chassis to produce biofuels and bioproducts due to its high tolerance to multiple environmental stresses such as low pH, heat, and other chemicals otherwise toxic for the most widely used microbes. Yet, little is known about specific mechanisms of such tolerance in this organism, hindering our ability to engineer this species to produce valuable biochemicals. Here, we report a comprehensive study of the mechanisms of acidic tolerance in this species via transcriptome profiling across variable pH for 12 different strains with different phenotypes. We found multiple regulatory mechanisms involved in tolerance to low pH in different strains of , marking potential targets for future gene editing and perturbation experiments.
Topics: Pichia; Transcriptome; Gene Expression Profiling; Hydrogen-Ion Concentration
PubMed: 38018981
DOI: 10.1128/spectrum.02536-23 -
Scientific Reports Nov 2023Second-generation bioethanol production using lignocellulosic biomass as feedstock requires a highly efficient multistress-tolerant yeast. This study aimed to develop a...
Adaptive laboratory evolution under acetic acid stress enhances the multistress tolerance and ethanol production efficiency of Pichia kudriavzevii from lignocellulosic biomass.
Second-generation bioethanol production using lignocellulosic biomass as feedstock requires a highly efficient multistress-tolerant yeast. This study aimed to develop a robust yeast strain of P. kudriavzevii via the adaptive laboratory evolution (ALE) technique. The parental strain of P. kudriavzevii was subjected to repetitive long-term cultivation in medium supplemented with a gradually increasing concentration of acetic acid, the major weak acid liberated during the lignocellulosic pretreatment process. Three evolved P. kudriavzevii strains, namely, PkAC-7, PkAC-8, and PkAC-9, obtained in this study exhibited significantly higher resistance toward multiple stressors, including heat, ethanol, osmotic stress, acetic acid, formic acid, furfural, 5-(hydroxymethyl) furfural (5-HMF), and vanillin. The fermentation efficiency of the evolved strains was also improved, yielding a higher ethanol concentration, productivity, and yield than the parental strain, using undetoxified sugarcane bagasse hydrolysate as feedstock. These findings provide evidence that ALE is a practical approach for increasing the multistress tolerance of P. kudriavzevii for stable and efficient second-generation bioethanol production from lignocellulosic biomass.
Topics: Acetic Acid; Cellulose; Ethanol; Saccharomyces cerevisiae; Biomass; Furaldehyde; Saccharum; Fermentation
PubMed: 38017261
DOI: 10.1038/s41598-023-48408-7 -
Molecules (Basel, Switzerland) Nov 2023species produce different classes of antimicrobial and antioxidant substances: peptides or proteins with different structural compositions and molecular masses and a...
species produce different classes of antimicrobial and antioxidant substances: peptides or proteins with different structural compositions and molecular masses and a broad range of volatile organic compounds (VOCs), some of which may serve as biomarkers for microorganism identification. The aim of this study is the identification of biologically active compounds synthesized by five species using gas chromatography coupled to mass spectrometry (GC-MS). The current study profoundly enhances the knowledge of antibacterial and antioxidant metabolites ensuring the unambiguous identification of VOCs produced by some species, which were isolated from vegetable samples of potato, carrot, and tomato. Phylogenetic and biochemical studies were used to identify the bacterial isolates after culturing. Phylogenetic analysis proved that five bacterial isolates BSS12, BSS13, BSS16, BSS21, and BSS25 showed 99% nucleotide sequence similarities with AS-08, WAB2133, NiuFun, FORT 102, and F3, respectively. The crude extract was prepared from bacterial isolates to assess the antibiotic resistance potency and the antimicrobial potential against various targeted multidrug-resistant strains, including yeast strains such as , , and bacterial strains of , , , , , , group B, , , , , , and . GC-MS analysis of bacterial strains found that VOCs from species come in a variety of chemical forms, such as ketones, alcohols, terpenoids, alkenes, etc. Overall, 69 volatile organic compounds were identified from five species, and all five were found to share different chemical classes of volatile organic components, which have a variety of pharmacological applications. However, eight antibacterial compounds with different concentrations were commonly found in all five species: acetoin, acetic acid, butanoic acid, 2-methyl-, oxime-, methoxy-phenyl, phenol, 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester, nonanoic acid, and hexadecanoic acid, methyl. The present study has demonstrated that bacterial isolates BSS25, BSS21, and BSS16 display potent inhibitory effects against , while BSS25, BSS21, and BSS13 exhibit the ability to restrain the growth and activity of . Notably, BSS25 and BSS21 are the only isolates that demonstrate substantial inhibitory activity against . This disparity in inhibitory effects could be attributed to the higher concentrations of acetoin in BSS25 and BSS21, whereas BSS16 and BSS13 have relatively elevated levels of butanoic acid, 2-methyl-. Certainly, the presence of acetoin and butanoic acid, 2-methyl-, contributes to the enhanced antibacterial potential of these bacterial strains, in conjunction with other organic volatile compounds and peptides, among other factors. The biology and physiology of can be better understood using these results, which can also be used to create novel biotechnological procedures and applications. Moreover, because of its exceptional ability to synthesize and produce a variety of different antibacterial compounds, species can serve as natural and universal carriers for antibiotic compounds in the form of probiotic cultures and strains to fight different pathogens, including mycobacteria.
Topics: Anti-Bacterial Agents; Gas Chromatography-Mass Spectrometry; Volatile Organic Compounds; Antioxidants; Butyric Acid; Acetoin; Phylogeny; Bacillus; Anti-Infective Agents; Escherichia coli; Bacillus cereus; Enterobacter aerogenes; Peptides; Microbial Sensitivity Tests
PubMed: 38005278
DOI: 10.3390/molecules28227556 -
Food Research International (Ottawa,... Dec 2023Considering the significance and scarcity of quality protein, this study aims to obtain a novel safe protein source through fermenting the black soldier fly larvae...
Considering the significance and scarcity of quality protein, this study aims to obtain a novel safe protein source through fermenting the black soldier fly larvae (BSFL). Lactobacillus crispatus M1027 and Pichia kudriavzevii DHX19 were added as starters together with neutral protease for enzymolysis during fermentation. The results showed that the low pH value (from 6.60 to 3.99), generated by lactic acid accumulation, created an environment where the pathogen could hardly grow. During fermentation, the flavor compound ethyl acetate content reached up to 406.55 mg/L, and the melanization was effectively inhibited by the starters. The increase of trichloroacetic acid-soluble protein content (from 8.73 % to 17.96 %) contributed to improving the absorbability of product by animals after feeding. Notably, the contents of detrimental substances, including total volatile basic nitrogen and histamine, were both below specified limits after fermentation. Simultaneously, the malonic dialdehyde content remained stable during fermentation. Relative abundance of Lactobacillus and Pichia gradually increased and finally dominated in the culture during fermentation, accompanied by pathogens decline below detection limit (1.0 Log cfu/g). Moreover, there was a close relationship between the dynamics of physicochemical indices and microbial succession. Overall, our studies explored a new process to ferment the BSFL paste which would improve the quality and safety of fermented BSFL paste. This research provided theoretical support for fermented insect as a novel protein source.
Topics: Animals; Larva; Fermentation; Diptera; Lactobacillus; Microbiota
PubMed: 37986475
DOI: 10.1016/j.foodres.2023.113624 -
BMC Microbiology Nov 2023Plant fungal pathogens cause substantial economic losses through crop yield reduction and post-harvest storage losses. The utilization of biocontrol agents presents a...
BACKGROUND
Plant fungal pathogens cause substantial economic losses through crop yield reduction and post-harvest storage losses. The utilization of biocontrol agents presents a sustainable strategy to manage plant diseases, reducing the reliance on hazardous chemical. Recently, Pichia kudriavzevii has emerged as a promising biocontrol agent because of its capacity to inhibit fungal growth, offering a potential solution for plant disease management.
RESULTS
Two novel Pichia kudriavzevii strains, Pk_EgyACGEB_O1 and Pk_EgyACGEB_O2, were isolated from olive brine samples. The microscopic characterization of the strains revealed similar structures. However, there were noticeable differences in their visual morphology. Based on their internal transcribed spacer (ITS) DNA sequences, Pk_EgyACGEB_O1 and Pk_EgyACGEB_O2 strains assigned by GenBank IDs MZ507552.1 and MZ507554.1 shared high sequence similarity (~ 99.8% and 99.5%) with P. kudriavzevii, respectively. Both strains were evaluated in vitro against plant pathogenic fungi. The strains revealed the ability to consistently inhibit fungal growth, with Pk_EgyACGEB_O2 showing higher effectiveness. In addition, both P. kudriavzevii strains effectively controlled grey mold disease caused by B. cinerea in golden delicious apples, suggesting their potential as sustainable and eco-friendly biocontrol agents for post-harvest diseases. Based on a comprehensive bioinformatics pipeline, candidate-secreted proteins responsible for the potent antifungal activity of P. kudriavzevii were identified. A total of 59 proteins were identified as common among the P. kudriavzevii CBS573, SD108, and SD129 strains. Approximately 23% of the secreted proteins in the P. kudriavzevii predicted secretome are hydrolases with various activities, including proteases, lipases, glycosidases, phosphatases, esterases, carboxypeptidases, or peptidases. In addition, a set of cell-wall-related proteins was identified, which might enhance the biocontrol activity of P. kudriavzevii by preserving the structure and integrity of the cell wall. A papain inhibitor was also identified and could potentially offer a supplementary defense against plant pathogens.
CONCLUSION
Our results revealed the biocontrol capabilities of P. kudriavzevii against plant pathogenic fungi. The research focused on screening novel strains for their ability to inhibit the growth of common pathogens, both in vitro and in vivo. This study shed light on how P. kudriavzevii interacts with fungal pathogens. The findings can help develop effective strategies for managing plant diseases.
Topics: Pichia; Antifungal Agents; Mycoses; Plant Diseases
PubMed: 37980509
DOI: 10.1186/s12866-023-03047-w -
Food Chemistry Apr 2024This study is the first to demonstrate the yeast Pichia kudriavzevii can effectively deliver Se and investigate the distribution and species of Se in Se-enriched P....
This study is the first to demonstrate the yeast Pichia kudriavzevii can effectively deliver Se and investigate the distribution and species of Se in Se-enriched P. kudriavzevii. Results showed that P. kudriavzevii can accumulate Se and convert 84.883% of absorbed Se into organic forms, of which 78.338% was incorporated into protein, 1.978% combined with polysaccharides, and 0.456% bound to nucleic acid. Besides, water-soluble, salt-soluble, and alkali-soluble proteins account for 49.398%, 1.867%, and 20.628% of selenoprotein, respectively. The dominant Se species were SeCys2 and MeSeCys. Additionally, Se-enrichment enhanced nutritional value of P. kudriavzevii by increasing the levels of amino acids, iron, and zinc. The activity of key rate-limiting enzyme sephosphate synthetase involved in Se biotransformation was improved after Se enrichment. The extracellular pH results suggest that Se enrichment ability can be further enhanced by elevating pH. These results suggest P. kudriavzevii holds great promise as an effective vehicle for delivering Se.
Topics: Selenium; Pichia; Biotransformation; Zinc
PubMed: 37976881
DOI: 10.1016/j.foodchem.2023.137966 -
Scientific Reports Nov 2023This study addresses the environmental risks associated with the accumulation of keratin waste from poultry, which is resistant to conventional protein degradation...
This study addresses the environmental risks associated with the accumulation of keratin waste from poultry, which is resistant to conventional protein degradation methods. To tackle this issue, microbial keratinases have emerged as promising tools for transforming resilient keratin materials into valuable products. We focus on the Metalloprotease (MetPr) gene isolated from novel Pichia kudriavzevii YK46, sequenced, and deposited in the NCBI GenBank database with the accession number OQ511281. The MetPr gene encodes a protein consisting of 557 amino acids and demonstrates a keratinase activity of 164.04 U/ml. The 3D structure of the protein was validated using Ramachandran's plot, revealing that 93% and 97.26% of the 557 residues were situated within the most favoured region for the MetPr proteins of template Pichia kudriavzevii strain 129 and Pichia kudriavzevii YK46, respectively. Computational analyses were employed to determine the binding affinities between the deduced protein and beta keratin. Molecular docking studies elucidated the optimal binding affinities between the metalloprotease (MetPr) and beta-keratin, yielding values of - 260.75 kcal/mol and - 257.02 kcal/mol for the template strains Pichia kudriavzevii strain 129 and Pichia kudriavzevii YK46, respectively. Subsequent molecular cloning and expression of the MetPr gene in E. coli DH5α led to a significantly higher keratinase activity of 281 ± 12.34 U/ml. These findings provide valuable insights into the potential of the MetPr gene and its encoded protein for keratin waste biotransformation, with implications for addressing environmental concerns related to keratinous waste accumulation.
Topics: Animals; Feathers; Escherichia coli; Molecular Docking Simulation; Pichia; Metalloproteases; Keratins; Cloning, Molecular
PubMed: 37968282
DOI: 10.1038/s41598-023-47179-5 -
Brazilian Journal of Microbiology :... Mar 2024Enzymatic compounds can be found abundantly and provide numerous advantages in microbial organisms. Xylanases are used in various pharmaceutical, food, livestock,...
Enzymatic compounds can be found abundantly and provide numerous advantages in microbial organisms. Xylanases are used in various pharmaceutical, food, livestock, poultry, and paper industries. This study aimed to investigate xylanase-producing yeasts, xylose concentration curve and their enzymatic activity under various factors including carbon and nitrogen sources, temperature, and pH. Enzyme activity was evaluated under different conditions before, during, and after purification. The yeast strains were obtained from the wood product workshop and were subsequently cultivated on YPD (yeast extract peptone dextrose) medium. Additionally, the growth curve of the yeast and its molecular identification were conducted. The optimization and design process of xylan isolated from corn wood involved the use of Taguchi software to test different parameters like carbon and nitrogen sources, temperature, and pH, with the goal of determining the most optimal conditions for enzyme production. In addition, the Taguchi method was utilized to conduct a multifactorial optimization of xylanase enzyme activity. The isolated species were partially purified using ammonium sulfate precipitation and dialysis bag techniques. The results indicated that 3 species (8S, 18S, and 16W) after molecular identification based on 18S rRNA gene sequencing were identified as Candida tropicalis SBN-IAUF-1, Candida tropicalis SBN-IAUF-3, and Pichia kudriavzevii SBN-IAUF-2, respectively. The optimal parameters for wheat carbon source and peptone nitrogen source were found at 50 °C and pH 9.0 through single-factor optimization. By using the Taguchi approach, the best combination for highest activity was rice-derived carbon source and peptone nitrogen source at 50 °C and pH 6.0. The best conditions for xylanase enzyme production in single-factor optimization of wheat bran were 2135.6 U/mL, peptone 4475.25 U/mL, temperature 50 °C 1868 U/mL, and pH 9.0 2002.4 U/mL. Among the tested yeast, Candida tropicalis strain SBN-IAUF-1 to the access number MZ816946.1 in NCBI was found to be the best xylanase product. The highest ratio of enzyme production at the end of the delayed phase and the beginning of the logarithmic phase was concluded by comparing the growth ratio of 8S, 16W, and 18S yeasts with the level of enzymatic activity. This is the first report on the production of xylan polymer with a relative purity of 80% in Iran. The extracellular xylanases purified from the yeast species of C. tropicalis were introduced as a desirable biocatalyst due to their high enzymatic activity for the degradation of xylan polymers.
Topics: Wood; Xylans; Candida tropicalis; Peptones; Fermentation; Yeasts; Carbon; Nitrogen; Endo-1,4-beta Xylanases; Pichia
PubMed: 37957443
DOI: 10.1007/s42770-023-01171-3 -
Asian Pacific Journal of Cancer... Oct 2023Candida krusei is the cause of the fungal infection candidiasis, which has a high mortality rate. Intrinsic resistance to fluconazole can cause the failure of Krusei...
BACKGROUND
Candida krusei is the cause of the fungal infection candidiasis, which has a high mortality rate. Intrinsic resistance to fluconazole can cause the failure of Krusei candidiasis treatment. Therefore, it is necessary to find alternative drugs to eliminate the fungus. Extracts of Syzygium aromaticum and Alpinia purpurata have been proven to be alternative solutions for treating Candida krusei resistance.
OBJECTIVE
This study aims to explore the active compounds Syzygium aromaticum and Alpinia purpurata as treatments against Candida krusei through bioactivity tests, molecular modeling, and toxicity tests.
METHODS
Determination of antifungal activity with the agar well diffusion and microbroth dilution method. Molecular modeling was conducted using the following software: Marvin Sketch, LigandScout 4.4.5, AutoDock ver 4.2.6, PyMOL, LigPlus, MOE ver 2008.
RESULT
Bioactivity test results of the two natural extracts against C. krusei ATCC 6258, it was found that the S. aromaticum and A. purpurata extracts have MIC50 values of 0.031 μg/mL and 1.435x105 μg/mL. The molecular modeling found that the compounds Benzotriazole, 1-(4-methyl-3-nitrobenzoyl)-, 1,3,4-Eugenol Acetate, Stigmasta-5,22-dien-3-ol, acetate (3 beta)- and Farnesyl acetate from the two natural extracts, interacts with the active site of the enzyme lanosterol-14-α-demethylase with a binding energy of -8.91, -6.04, -13.53, and -7.15 kcal/mol. The oral acute toxicity test of S. aromaticum and A. purpurata extracts proved that the LD50 was >6000 mg/kg BW and >8000 mg/kg BW. The acute dermal toxicity test of the two extracts showed that the LD50 was >6000 mg/kg BW.
CONCLUSION
S. aromaticum and A. purpurata extracts have been proven to be alternative solutions for treating Candida krusei resistance.
Topics: Humans; Antifungal Agents; Syzygium; Alpinia; Plant Extracts; Microbial Sensitivity Tests; Candidiasis; Toxicity Tests; Acetates
PubMed: 37898844
DOI: 10.31557/APJCP.2023.24.10.3403 -
Molecules (Basel, Switzerland) Oct 2023The aim of this study was to investigate the compounds in the hexane extract of (Savi.) Ten. and to determine the antibacterial, antifungal, and antioxidant activities...
The aim of this study was to investigate the compounds in the hexane extract of (Savi.) Ten. and to determine the antibacterial, antifungal, and antioxidant activities of different extracts. The (NGBB 7229) plant was collected from Turkey's Trakya region. Crude extracts were obtained using different solvents. The chemical composition of was determined in hexane extract using gas chromatography mass spectrometry. The antioxidant activities of the extracts were evaluated by Trolox equivalent antioxidant activity (TEAC), ferric-reducing antioxidant power (FRAP), cupric-reducing antioxidant capacity (CUPRAC), the β-carotene bleaching method, and the determination of superoxide anion scavenging activities. The antibacterial activity was tested against , , , , , and , whereas the antifungal activity was tested against , , and by applying microdilution methods. A total of 41 bioactive compounds were identified using the GC-MS library. Terpenoids were found to be dominant (52.89%), and lup-20(29)-en-3-yl-acetate and lupeol were the most abundant terpenoids. The highest total flavonoid content (25.73 mg catechin/g) and antioxidant capacity were found in the methanolic extract. The highest antibacterial activity was detected against in the ethyl acetate extract, and the highest antifungal activity was found against and in the hexane extract. The observed antioxidant characteristics of the extracts could be attributed to the presence of flavonoids. The high antifungal activity of the hexane extract against all fungal strains can be attributed to its constituents, i.e., terpenoids. This study discloses the potential antioxidant and antimicrobial activities, including some bioactive components, of and implies that holds possible applications in the food and pharmaceutical industries as an antioxidant, antibacterial, and antifungal agent.
Topics: Antioxidants; Antifungal Agents; Cirsium; Hexanes; Plant Extracts; Anti-Infective Agents; Anti-Bacterial Agents; Flavonoids; Terpenes; Candida albicans
PubMed: 37894654
DOI: 10.3390/molecules28207177