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Frontiers in Microbiology 2022Heterotrophic nitrification is a process of organic nitrogen degradation completed by the participation of heterotrophic nitrifying microorganisms, which can accelerate...
Heterotrophic nitrification is a process of organic nitrogen degradation completed by the participation of heterotrophic nitrifying microorganisms, which can accelerate the nitrogen transformation process. However, the current research mainly focuses on heterotrophic nitrifying bacteria and their ammonium degradation capacities. And there is little accumulation of research on fungi, the main force of heterotrophic nitrification, and their capacities to transform organic nitrogen. In this study, novel heterotrophic nitrifying fungus (XTY1) and bacterium (GS2) were screened and isolated from upland soil, and the strains were identified and registered through GenBank comparison. After 24 h single nitrogen source tests and N labeling tests, we compared and preliminarily determined the heterotrophic nitrification capacities and pathways of the two strains. The results showed that XTY1 and GS2 had different transformation capacities to different nitrogen substrates and could efficiently transform organic nitrogen. However, the transformation capacity of XTY1 to ammonium was much lower than that of GS2. The two strains did not pass through NHOH and NO during the heterotrophic nitrification of organic nitrogen, and mainly generated intracellular nitrogen and low NO. Other novel organic nitrogen metabolism pathways may be existed, but they remain to be further validated.
PubMed: 36569078
DOI: 10.3389/fmicb.2022.1038599 -
Microorganisms Apr 2022Microbial administration has been used successfully to improve host health. However, the positive effects of endogenous microbials are still underexplored. This study...
Microbial administration has been used successfully to improve host health. However, the positive effects of endogenous microbials are still underexplored. This study investigated the effects of bovine Lactic acid bacteria and yeast on the milk production, quality and digestive tract microbiome of dairy cows. Y9, T7 and isolated from high-yielding dairy cows were selected to feed low-yielding Holstein cows. T7 could significantly increase milk yield, meanwhile, T7 and B14 could obviously reduce the number of somatic cell counts (SCC). However, slight differences were found in milk fat, protein, lactose and SNF (solids not fat) percentage. High throughput sequencing showed that the dominant bacteria were and in rumen and feces, respectively, and the dominant fungi were , and in both samples, before and after feeding the microbial addition. Nonetheless, microbial addition changed the abundance and structure of the microbiome in the digestive tract. Our data showed bovine yeast and LAB were beneficial for improving performance and regulating the microbial structure of dairy cows. This study was expected to enrich the knowledge of the digestive tract microbiome in dairy cows and provide a feasible strategy for the further utilization of bovine microorganisms.
PubMed: 35630288
DOI: 10.3390/microorganisms10050842 -
Journal of Basic Microbiology Sep 2019Removal of heavy metals from food material by growing micro-organisms is limited by the toxicity to cells. In this study, different preincubation treatments were...
Removal of heavy metals from food material by growing micro-organisms is limited by the toxicity to cells. In this study, different preincubation treatments were investigated to analyze their effects on cadmium resistance and removal ability of Pichia kudriavzevii A16 and Saccharomyces cerevisiae CICC1211. Sucrose preincubation improved the cadmium resistance of both yeast cells and increased the cadmium-removal rate of P. kudriavzevii A16. An evident decrease of intracellular and cell-surface cadmium accumulation was observed after sucrose preincubation, which may be the primary reason responsible for the improved cadmium resistance. Flow cytometry assay showed that sucrose significantly reduced the production of reactive oxygen species (ROS) and cell death rate of both yeasts under cadmium compared with those normally cultured cells. Under cadmium stress, the content of both protein carbonyls and malonyldialdehyde were also reduced by the addition of sucrose, the results were in accordance with the tendency of ROS, exhibiting a defending function of sucrose. Osmotic regulators as proline and trehalose were increased by sucrose preincubation in P. kudriavzevii A16 in the presence of cadmium. The results suggested that sucrose preincubation could be applied to improve cadmium resistance and removal rate of yeasts.
Topics: Biodegradation, Environmental; Cadmium; Microbial Viability; Pichia; Proline; Reactive Oxygen Species; Saccharomyces cerevisiae; Stress, Physiological; Sucrose; Trehalose
PubMed: 31347180
DOI: 10.1002/jobm.201900272 -
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 -
Animals : An Open Access Journal From... Apr 2020The objective of this study was to determine the effect of supplementing CPY1, RSY5 and YSY2 isolated from ruminal fluid of dairy cows on transfer of aflatoxin B...
The objective of this study was to determine the effect of supplementing CPY1, RSY5 and YSY2 isolated from ruminal fluid of dairy cows on transfer of aflatoxin B (AFB) from feed into aflatoxin M (AFM) in milk, DMI, milk production and nutrient digestibility. Four multiparous Holsteins in mid-lactation were used in a 4 × 4 Latin square design trial consisting of 14 days in each experimental period for sample collection. Between each period, 14 clearance days prior to the next treatment were allowed to minimize carryover effects. In each treatment, subsequent supplementation of isolated yeast was compared, i.e., (1) control (without yeast supplementation), (2) CPY1 (K1Y), (3) RSY5 (K2Y) and (4) YSY2 (PY). All diets contained 22.28 µg of AFB/kg. Treatments were individually fed at the rate of 2 g/day (1 × 10 CFU/g) of yeast biomass or corn meal in the control group. Concentrations of AFM in milk was reduced with yeast and averaged 1.54, 0.36, 0.43 and 0.51 µg/L for control, K1Y, K2Y and PY, respectively ( < 0.01). The transfer of AFB from feed into AFM in milk was higher in control compared with K1Y, K2Y and PY (7.26% vs. 1.18%, 1.44% and 1.69% respectively, < 0.01). Supplementation of yeast also improved DMI and milk compositions, but no differences were observed in nutrient digestibility or milk yield among treatments. Concentration and yield of milk protein, fat, lactose, solid-not-fat (SNF) and total solids were greater in cows fed yeast compared with the control ( < 0.01). These results indicate that CPY1, RSY5 and YSY2 shows promise as a dietary supplementation to detoxify AFB and improve DMI and yield of milk components.
PubMed: 32325721
DOI: 10.3390/ani10040709 -
Foods (Basel, Switzerland) Jun 2022This study investigated the spoilage potential of yeast strains (Km1, Km2 and Km3) Pk1 and Td1 grown in skyr in cold storage. Yeast strains were isolated from skyr and...
This study investigated the spoilage potential of yeast strains (Km1, Km2 and Km3) Pk1 and Td1 grown in skyr in cold storage. Yeast strains were isolated from skyr and identified by sequencing of the 26S rRNA gene. yeasts were grown in skyr to high numbers, generating large amounts of volatile organic compounds (VOC) associated with off-flavours, among them were alcohols (3-methyl-1-butanol, 2-methyl-1-propanol and 1-hexanol), esters (ethyl acetate and 3-methylbutyl acetate) and aldehydes (hexanal, methylbutanal and methylpropanal). Growth of Pk1 led to moderate increases in several alcohols and esters (mostly, 3-methyl-1-butanol and ethyl acetate), whereas only minor shifts in VOCs were associated with Td2. The levels of the key aroma compounds, diacetyl and acetoin, were significantly decreased by all strains and Pk1. In contrast to the other yeast species, was able to utilize lactose, producing ethanol and carbon dioxide. Based on the overall results, was characterised by the highest spoilage potential. The study revealed the differences between the yeast species in fermentative and spoilage activities, and clarified the role of yeast metabolites for off-flavour formation and quality defects in skyr during cold storage.
PubMed: 35741978
DOI: 10.3390/foods11121776 -
Current Opinion in Critical Care Oct 2023The increasing incidence of drug-resistant Candida brings a new challenge to the treatment of invasive candidiasis. Although cross-resistance among azoles and... (Review)
Review
PURPOSE OF REVIEW
The increasing incidence of drug-resistant Candida brings a new challenge to the treatment of invasive candidiasis. Although cross-resistance among azoles and echinocandins was generally uncommon, reports of multidrug-resistant (MDR) Candida markedly increased in the last decade. The purpose of this review is to understand mechanisms and risk factors for resistance and how to tackle antifungal resistance.
RECENT FINDINGS
The paper describes the action of the three main classes of antifungals - azoles, echinocandins and polyenes - and Candida's mechanisms of resistance. The current evolution from cross-resistance to multiresistance among Candida explains the modern glossary - multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR) - imported from bacteria. MDR Candida most commonly involves acquired resistance in species with intrinsic resistance, therefore it mostly involves C. glabrata, C. parapsilosis, C. krusei, C guilliermondii or C. auris , which is intrinsically multidrug resistant. Finally, strategies to tackle antifungal resistance became clearer, ideally implemented through antifungal stewardship.
SUMMARY
Avoiding antifungal's overuse and selecting the best drug, dose and duration, when they are needed, is fundamental. Knowledge of risk factors for resistance, microbiological diagnosis to the species, use of susceptibility test supported by antifungal stewardship programs help attaining effective therapy and sustaining the effectiveness of the current antifungal armamentarium.
Topics: Humans; Candida; Antifungal Agents; Candidiasis, Invasive; Echinocandins; Azoles
PubMed: 37641511
DOI: 10.1097/MCC.0000000000001077 -
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 -
Letters in Applied Microbiology Sep 2023Film-forming yeasts are potential sources of defects in alcoholic beverages. The aim of this study is to assess the growth capacity of Pichia and Candida film-forming...
Film-forming yeasts are potential sources of defects in alcoholic beverages. The aim of this study is to assess the growth capacity of Pichia and Candida film-forming yeasts in cider and wine and the effects on their chemical composition. Cider, partially and fully fermented wine were inoculated with strains of C. californica, P. fermentans, P. kluyveri, P. kudriavzevii, P. manshurica, and P. membranifaciens to simulate a post-fermentative contamination. The former three species grew only in cider. Pichia manshurica and P. kudriavzevii displayed high viability in wine up to 13.18% (v v-1) ethanol. Significant changes in odour-active molecules from different chemical groups were observed in cider and wine in the inoculated samples, compared to the non-inoculated ones. Cider is more susceptible to contamination by all of the species tested, due to its low alcohol content, while P. membranifaciens, P. manshurica, and P. kudriavzevii are additionally potential spoilage agents of wine. This study highlights the risk of cider and wine contamination by film-forming yeasts. Their impact on aroma profiles depends on their ability to grow and their metabolism. This study contributes to an understanding of the possible physiological and metabolic mechanisms responsible for film formation and chemical changes in alcoholic beverages.
Topics: Wine; Fermentation; Pichia; Alcoholic Beverages; Candida
PubMed: 37656878
DOI: 10.1093/lambio/ovad099 -
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