Candida Tropicalis Strains Research Articles

In Vivo Microevolutionary Analysis of a Fatal Case of Rhinofacial and Disseminated Mycosis Due to Azole-Drug-Resistant Candida Species.

Ten Candida species strains were isolated from the first known fatal case of rhinofacial and rhino-orbital-cerebral candidiasis. Among them, five strains of Candida parapsilosis complex were isolated during the early stage of hospitalization, while five strains of Candida tropicalis were isolated in the later stages of the disease. Using whole-genome sequencing, we distinguished the five strains of C. parapsilosis complex as four Candida metapsilosis strains and one Candida parapsilosis strain. Antifungal susceptibility testing showed that the five strains of C. parapsilosis complex were susceptible to all antifungal drugs, while five C. tropicalis strains had high minimum inhibitory concentrations to azoles, whereas antifungal-drug resistance gene analysis revealed the causes of azole resistance in such strains. For the first time, we analyzed the microevolutionary characteristics of pathogenic fungi in human hosts and inferred the infection time and parallel evolution of C. tropicalis strains. Molecular clock analysis revealed that azole-resistant C. tropicalis infection occurred during the first round of therapy, followed by divergence via parallel evolution in vivo. The presence/absence variations indicated a potential decrease in the virulence of genomes in strains isolated following antifungal drug treatment, despite the absence of observed clinical improvement in the conditions of the patient. These results suggest that genomic analysis could serve as an auxiliary tool in guiding clinical diagnosis and treatment.

Synergistic Anticandidal Effectiveness of Greenly Synthesized Zinc Oxide Nanoparticles with Antifungal Agents against Nosocomial Candidal Pathogens.

The high prevalence of fungal resistance to antifungal drugs necessitates finding new antifungal combinations to boost the antifungal bioactivity of these agents. Hence, the aim of the present investigation was to greenly synthesize zinc oxide nanoparticles (ZnO-NPs) using an aqueous leaf extract of Salvia officinalis and investigate their antifungal activity and synergistic efficiency with common antifungal agents. The biofabricated ZnO-NPs were characterized to detect their physicochemical properties. A disk diffusion assay was employed to investigate the antifungal effectiveness of the greenly synthesized ZnO-NPs and evaluate their synergistic patterns with common antifungal agents. The Candida tropicalis strain was detected to be the most susceptible strain to ZnO-NPs at both tested concentrations of 50 and 100 µg/disk, demonstrating relative suppressive zones of 19.68 ± 0.32 and 23.17 ± 0.45 mm, respectively. The minimum inhibitory concentration (MIC) of ZnO-NPs against the C. tropicalis strain was 40 µg/mL, whereas the minimum fungicidal concentration (MFC) was found to be 80 µg/mL. The highest synergistic efficiency of the biogenic ZnO-NPs with terbinafine antifungal agent was detected against the C. glabrata strain, whereas the highest synergistic efficiency was detected with fluconazole against the C. albicans strain, demonstrating relative increases in fold of inhibition area (IFA) values of 6.82 and 1.63, respectively. Moreover, potential synergistic efficiency was detected with the nystatin antifungal agent against the C. tropicalis strain with a relative IFA value of 1.06. The scanning electron microscopy (SEM) analysis affirmed the morphological deformations of candidal cells treated with the biosynthesized ZnO-NPs as the formation of abnormal infoldings of the cell wall and membranes and also the formation of pores in the cell wall and membranes, which might lead to the leakage of intracellular constituents. In conclusion, the potential synergistic efficiency of the biogenic ZnO-NPs with terbinafine, nystatin, and fluconazole against the tested candidal strains highlights the potential application of these combinations in formulating novel antifungal agents of high antimicrobial efficiency. The biogenic ZnO nanoparticles and antifungal drugs exhibit powerful synergistic efficiency, which highlights their prospective use in the formulation of efficient antimicrobial medications, including mouthwash, ointments, lotions, and creams for effective candidiasis treatment.

In Vitro Antifungal Activity of Three Synthetic Peptides against Candida auris and Other Candida Species of Medical Importance.

Candidiasis is an opportunistic infection affecting immunosuppressed and hospitalized patients, with mortality rates approaching 40% in Colombia. The growing pharmacological resistance of Candida species and the emergence of multidrug-resistant Candida auris are major public health problems. Therefore, different antimicrobial peptides (AMPs) are being investigated as therapeutic alternatives to control candidiasis effectively and safely. This work aimed to evaluate the in vitro antifungal activity of three synthetic AMPs, PNR20, PNR20-1, and 35409, against ATCC reference strains of Candida albicans, Candida glabrata, Candida parapsilosis, Candida krusei, and Candida tropicalis, and clinical isolates of C. auris. Antifungal susceptibility testing, determined by broth microdilution, showed that the AMPs have antifungal activity against planktonic cells of all Candida species evaluated. In C. auris and C. albicans, the peptides had an effect on biofilm formation and cell viability, as determined by the XTT assay and flow cytometry, respectively. Also, morphological alterations in the membrane and at the intracellular level of these species were induced by the peptides, as observed by transmission electron microscopy. In vitro, the AMPs had no cytotoxicity against L929 murine fibroblasts. Our results showed that the evaluated AMPs are potential therapeutic alternatives against the most important Candida species in Colombia and the world.

Evidences for the augmented Cd(II) biosorption by Cd(II) resistant strain Candida tropicalis XTA1874 from contaminated aqueous medium

Cadmium is one of the most dreadful heavy metals and is becoming a major toxicant in ground water with increasing concentration above the WHO Guidelines in drinking water (0.003 mg/L). The potential sources of cadmium include sewage sludge, phosphate fertilizers and ingredients like Ni–Cd batteries, pigments, plating and plastics. Cadmium levels are increased in water owing to the use and disposal of cadmium containing ingredients. Water draining from a landfill may contain higher cadmium levels. The authors have tried to evaluate the optimized nutritional conditions for the optimal growth and Cd(II) remediation capacity for a developed Cd(II) resistant yeast strain named Candida tropicalis XTA 1874 isolated from contaminated water-body in West Bengal. By analyzing the optimization conditions, a synthetic medium was developed and the composition has been given in the main text. The strain showed much better Cd(II) adsorption capacity under the optimized nutritional conditions (Mean removal = 88.077 ± 0.097%).

Isolation and identification of non-saccharomyces ethanol and thermo-tolerant yeasts strains from fermented carbohydrate wastes

Ethanol is an important chemical with its potential as a biofuel to displace the environmentally unfriendly fossil fuels. Isolation and identification of ethanol and thermo-tolerant yeast capable of producing ethanol were carried out in this study. Seventy (70) samples from different fermented foods and agricultural wastes from millets, sorghum, maize, rice and guinea corn were obtained from local sellers in Panteka, Farin-Gida, Barkallahu and Barnawa in Kaduna State (North West), Nigeria were used in this research. The samples were collected using a sterile plastic container and were transported immediately to the Biotechnology laboratory of the Nigerian Defence Academy in iced chamber. They were serially diluted in distilled water and inoculated on yeast extract peptone dextrose agar (YEPD) media plates supplemented with 0.2% chloramphenicol. The plates were incubated at 30°C for 72 hours and developed colonies were sub-cultured to obtain pure culture which was observed for their morphological and microscopic characteristics. After examination, ten (10) yeast isolates were obtained from the seventy (70) samples collected. Flocculation test, Hydrogen sulphide test, preliminary alcohol production and sugar fermentation test were carried out on the isolates and their tolerance to ethanol at varying concentration 5%-20% (v/v) and temperature at 37oC-45oC were studied. Using the internal transcribed spacer (ITS) 1 and 2 regions primer, the DNA were sequenced and the isolates identified. Four isolates FG 17, FG 27, P1 and BN50 showed ethanol tolerance potentials at 20% ethanol and were identified as strains of Diutina rugosa, Candida sp, Candida ethanolica and Candida tropicalis while one isolate FG 35 showed good thermo-tolerance ability at 45oC and was identified as Trichosporon sp.

New Benzopyrrole Derivatives: Synthesis and Appraisal of Their Potential as Antimicrobial Agents.

A series of twenty compounds (23-42) were synthesized and characterized by spectral studies in order to explore newer antimicrobial compounds. The majority of the synthesized compounds reported significant antimicrobial properties against various pathogenic bacterial and fungal strains with the help of tube dilution method. Significant activities (MIC ranging from 3.9 to 15.62 μg/ml) have been shown against Gram-negative and Gram-positive bacteria with. In contrast, moderate to outstanding antibacterial activity was reported versus Gram-negative bacteria such as E. coli and P. aeruginosa along with Gram-positive bacteria such as S. aureus and B. subtilis. While antifungal activity was moderate to excellent against two fungus strains (Candida tropicalis, Candida glabrata). Compounds 25 and 34 had the utmost activity versus Gram-positive and Gram-negative bacteria too. The antifungal activity of compound 35 was comparable to that of standard. In-silico Molecular docking evaluations were performed for antibacterial and antifungal activities against the target DNA gyrase A (PDB: 1AB4) and 14 alpha-sterol demethylase enzyme (PDB: 1EA1), respectively. The dock score for typicals compounds for antibacterial and antifungal activity were -4.733 and -9.4, respectively. The three-dimensional QSAR examination was carried out by multiple linear regression (SA-MLR) with good predictive power (r2=0.9105, q2=0.8011). Establishment of several interactions between the ligand 25 and 34 and the active site of residue of both receptors, enable the ligand 25 and 34 to be fit well in the pocket of the active site, as seen in Molecular dynamics simulations analysis. Thus, data suggest that these ligands could be further explored as potential precursors to develop antimicrobial drugs.

In vitro antifungal potency of the moronecidin-like peptide against Candida albicans, Candida glabrata, and Candida tropicalis.

The aim of this study was to investigate the in vitro antifungal potency of the moronecidin-like peptide against Candida albicans, Candida glabrata, and Candida tropicalis. To evaluate the antifungal effect of moronecidin-like peptide, the protocol presented in CLSI M27-A3 and CLSI M27-S4 was used and the minimum inhibitory concentration was determined. The minimum inhibitory effect of moronecidin-like peptide composition was 8 µg/ml for Candida tropicalis and Candida albicans and 32 µg/ml for Candida glabrata. The MIC of nystatin was determined to be 1.25 µg/ml for Candida glabrata and Candida albicans and 0.625 µg/ml for Candida tropicalis strains. The MFC composition of the moronecidin-like peptide was determined for Candida tropicalis and Candida albicans strains 8 µg/ml and for Candida glabrata strain 64 µg/ml. The results of cytotoxicity and hemolysis of the moronecidin peptide test on macrophage showed that moronecidin peptide has no cytotoxicity and toxicity properties. According to the results of the present study, the moronecidin-like peptide could be a new strategy in the treatment of infections caused by Candida strains. The discovery of the exact mechanism of which requires extensive clinical studies in this field.

Altered phagocytosis and morphogenesis of phenotypic switching-derived strains of the pathogenic Candida tropicalis co-cultured with phagocytic cells

Background and objectiveCandida tropicalis is among the most prevalent human pathogenic yeast species. Switch states of C. tropicalis differ in virulence traits. Here, we evaluate the effect of phenotypic switching on phagocytosis and yeast-hyphae transition in C. tropicalis. MethodsC. tropicalis morphotypes included a clinical strain and two switch strains (rough variant and rough revertant). In vitro, phagocytosis assay was performed using peritoneal macrophages and hemocytes. The proportion of hyphal cells was ascertained by scoring morphology using optical microscopy. Expression of the WOR1 (White-opaque regulator 1) and EFG1 (Enhanced filamentous growth protein 1) was determined by quantitative PCR. ResultsThe rough variant was more resistant to in vitro phagocytosis by peritoneal macrophages than that observed for the clinical strain, while hemocytes phagocytosed clinical and rough variant to the same extent. The rough revertant was more phagocytosed than the clinical strain by both phagocytes. During co-incubation with phagocytic cells, the clinical strain of C. tropicalis exists mainly as blastoconidia. The co-culture of the rough variant with macrophages resulted in a higher percentage of hyphae than blastoconidia cells, while in co-culture with hemocytes, no differences were observed between the percentage of hyphae and blastoconidia. The expression levels of WOR1 in the rough variant co-cultured with phagocytes were significantly higher than they were in the clinical strain. ConclusionsDifferences on phagocytosis and hyphal growth between switch states cells of C. tropicalis co-cultured with phagocytic cells were observed. The pronounced hyphal growth may affect the complex host-pathogen relationship and favor the pathogen to escape phagocytosis. The pleiotropic effects of phenotypic switching suggest that this event may contribute to the success of infection associated with C. tropicalis.

Xylitol Production by Candida tropicalis from Areca Nut Husk Enzymatic Hydrolysate and Crystallization.

Lignocellulosic biomasses are extensively used by researchers to produce a variety of renewable bioproducts. This research described an environment-friendly technique of xylitol production by an adapted strain of Candida tropicalis from areca nut hemicellulosic hydrolysate, produced through enzymatic hydrolysis. To enhance the activity of xylanase enzymes, lime and acid pretreatment was conducted to make biomass more amenable for saccharification. To improve the efficiency of enzymatic hydrolysis, saccharification parameters like xylanase enzyme loading were varied. Results exposed that the highest yield (g/g) of reducing sugar, about 90%, 83%, and 15%, were achieved for acid-treated husk (ATH), lime-treated husk (LTH), and raw husk (RH) at an enzyme loading of 15.0IU/g. Hydrolysis was conducted at a substrate loading of 2% (w/V) at 30°C, 100rpm agitation, for 12h hydrolysis time at pH 4.5 to 5.0. Subsequently, fermentation of xylose-rich hemicellulose hydrolysate was conducted with pentose utilizing the yeast Candida tropicalis to produce xylitol. The optimum concentration of xylitol was obtained at about 2.47g/L, 3.83g/L, and 5.88g/L, with yields of approximately 71.02%, 76.78%, and 79.68% for raw fermentative hydrolysate (RFH), acid-treated fermentative hydrolysate (ATFH), and lime-treated fermentative gydrolysate (LTFH), respectively. Purification and crystallization were also conducted to separate xylitol crystals, followed by characterization like X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. Results obtained from crystallization were auspicious, and about 85% pure xylitol crystal was obtained.

Synthesis of vanillin derivatives with 1,2,3‐triazole fragments and evaluation of their fungicide and fungistatic activities

Vanillin is the main component of natural vanilla extract and is responsible for its flavoring properties. Besides its well-known applications as an additive in food and cosmetics, it has also been reported that vanillin can inhibit fungi of clinical interest, such as Candida spp., Cryptococcus spp., Aspergillus spp., as well as dermatophytes. Thus, the present work approaches the synthesis of a series of vanillin derivatives with 1,2,3-triazole fragments and the evaluation of their antifungal activities against Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, Cryptococcus neoformans, Cryptococcus gattii, Trichophyton rubrum, and Trichophyton interdigitale strains. Twenty-two vanillin derivatives were obtained, with yields in the range of 60%-91%, from copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) click reaction between two terminal alkynes prepared from vanillin and different benzyl azides. In general, the evaluated compounds showed moderate activity against the microorganisms tested, with minimum inhibitory concentration (MIC) values ranging from 32 to >512 µg mL-1 . Except for compound 3b against the C. gattii R265 strain, all vanillin derivatives showed fungicidal activity for the yeasts tested. The predicted physicochemical and ADMET (absorption, distribution, metabolism, excretion, and toxicity) properties for the compounds indicated favorable profiles for drug development. In addition, a four-dimensional structure-activity relationship (4D-SAR) analysis was carried out and provided useful insights concerning the structures of the compounds and their biological profile. Finally, molecular docking calculations showed that all compounds bind favorably at the lanosterol 14α-demethylase enzyme active site with binding energies ranging from -9.1 to -12.2 kcal/mol.

Evaluation of Fermentative Xylitol Production Potential of Adapted Strains of Meyerozyma caribbica and Candida tropicalis from Rice Straw Hemicellulosic Hydrolysate

Dilute acid hydrolysis of lignocellulosic biomass generates inhibitors in the hydrolysate which hamper yeast metabolism and the fermentation process. Therefore, understanding the effect of these compounds on the performance of microorganisms becomes essential to achieve improved product yields. In this study, the effect of acetic acid, furfural, and hydroxymethylfurfural was evaluated on yeast growth and fermentation efficiency. Various parameters for the pretreatment of rice straw, such as an acid catalyst, and its concentration and residence time, were optimized for the maximum liberation of sugars in the hydrolysate. Further, the yeast strains Candida tropicalis and Meyerozyma caribbica were adapted for the tolerance of inhibitors at higher concentrations. A comparative analysis was carried out using un-adapted and adapted strains of Candida tropicalis and Meyerozyma caribbica for xylitol production. The findings of this study revealed that sulfuric acid (1.25% v/v) at 121 ரC for 30 min can efficiently convert rice straw xylan to xylose, with the release of 16.07 g/L xylose in the hydrolysate. Further, the adaptation results showed an increase of 76.42% and 69.33% in xylose assimilation by C. tropicalis and M. caribbica, respectively. The xylitol production with the adapted C. tropicalis was increased by 7.54% to 28.03 g/L xylitol. However, the xylitol production with the adapted M. caribbica was increased by 8.33%, yielding 26.02 g/L xylitol in the non-detoxified hydrolysate when compared to the un-adapted strains. Repeated batch fermentation was carried out for seven batches, and xylitol was found to be efficiently produced by the yeasts during five successive batches without any significant loss in the xylitol yield. Moreover, the results suggest that M. caribbica is a promising microorganism for the transformation of rice straw-derived xylose to xylitol.

Role of Fungi in Biodegradation of Imidazolium Ionic Liquids by Activated Sewage Sludge.

Ionic liquids (ILs), due to their specific properties, can play the role of persistent water contaminants. Fungi manifest the ability to decompose hardy degradable compounds, showing potential in the biodegradation of ILs, which has been studied extensively on sewage sludge; however, attention was drawn mainly to bacterial and not fungal species. The aim of the research was to determine the significance of fungi in ILs' biodegradation to extend the knowledge and possibly point out ways of increasing their role in this process. The research included: the isolation and genetic identification of fungal strains potentially capable of [OMIM][Cl], [BMIM][Cl], [OMIM][Tf2N], and [BMIM][Tf2N] degradation, adjustment of the ILs concentration for biodegradability test by MICs determination and choosing strains with the highest biological robustness; inoculum adaptation tests, and finally primary biodegradation by OECD 301F test. The study, conducted for 2 mM [OMIM][Cl] as a tested substance and consortium of microorganisms as inoculum, resulted in an average 64.93% biodegradation rate within a 28-day testing period. For the individual fungal strain (Candida tropicalis), the maximum of only 4.89% biodegradation rate was reached in 10 days, then inhibited. Insight into the role of fungi in the biodegradation of ILs was obtained, enabling the creation of a complex overview of ILs toxicity and the possibilities of its biological use. However, only an inoculum consisting of a consortium of microorganisms enriched with a selected strain of fungi was able to decompose the IL, in contrast to that consisting only of an individual fungal strain.

Evaluation of Non-Conventional Yeasts Isolated from Rotten Wood for Hydrolytic Activities and Xylose Fermentation

Hydrolysis of lignocellulose to fermentable sugars and their subsequent conversion to ethanol remain great challenges in the biofuel industry. Rotten wood is first colonized by bacteria and molds that possess strong hydrolases. Yeasts are also an important group of microorganisms that may participate in wood hydrolysis. Decaying wood could provide a rich natural reservoir of yeasts possessing promising hydrolytic activities, including xylanases, cellulases, β-glucosidases, or abilities essential for the fermentation of pentose sugars derived from lignocellulose degradation, especially xylose. Therefore, the aim of this work was to screen yeasts isolated from rotten wood samples for the production of hydrolytic enzymes directed at lignocellulose components and the ability to ferment xylose, L-arabinose, and cellobiose. Methods. Yeast strains were isolated from 22 samples of rotten wood and identified by phenotypic characteristics according to Kurtzman et al. Hydrolytic properties and the ability of the isolated strains to ferment xylose, L-arabinose, and cellobiose were determined using conventional methods. Results. 30 strains of yeasts and yeast-like micromycetes were isolated from 22 samples of rotten wood in the Holosiivskyi Forest, Kyiv. Based on phenotypic properties, most of the isolated yeasts belonged to ascomycetous yeasts and were represented by the following genera: Candida (8 strains), Debaryomyces (5 strains), Kluyveromyces (5 strains), Pichia (5 strains), Scheffersomyces (2 strains), Lachancea, Hanseniaspora, Saccharomyces, and Geotrichum/Galactomyces. A strain of yeast-like non-photosynthetic alga Prototheca sp. was also detected. Most of the isolated microfungi (66.6% isolates) exhibited extracellular β-glucosidase activity, two Candida tropicalis strains possessed weak pectinase and xylanase activity. None of the isolates demonstrated extracellular cellulase activity. Two yeast strains preliminarily identified as Scheffersomyces stipitis were able to ferment xylose at a concentration of 20—100 g/L over a wide temperature range up to 37°C. Acetic acid at 0.25—1% (v/v) concentration resulted in the complete inhibition of xylose fermentation. Ethanol production from xylose up to 6 g/L was observed under the microaerobic fermentation conditions for 24 hr at the substrate concentration 40 g/L, but the subsequent fermentation resulted in decreasing ethanol concentration presumably due to ethanol re-assimilation. None of the isolated strains was capable of fermenting cellobiose or L-arabinose under the microaerobic conditions. Conclusions. This work provides the characterization of yeast microbiota of rotten wood that was represented predominantly by ascomycetous yeasts. The dominant extracellular hydrolytic activity of the isolates was β-glucosidase. This is the first report on the isolation of xylose-fermenting yeasts Scheffersomyces stipitis in Ukraine, which comprised 7% of all the microfungi isolated from rotten wood.

LC-MS Analysis and Antifungal Activity of Turnera subulata Sm.

Fungi of the Candida genus are responsible for invasive candidiasis, which affects people all over the world and has high mortality rates. This is due to their virulence factors, which give them great resistance and pathogenicity. In addition, the emergence of multidrug-resistant strains makes it difficult to treat these infections. In this way, natural products have emerged as an alternative to standard drugs, where plants known for their medicinal properties such as Turnera subulata become attractive to research. The present work aimed to analyze the ethanol extract of Turnera subulata leaves against standard strains of Candida albicans, Candida krusei and Candida tropicalis using broth microdilution techniques. The identification of the compounds in T. subulata leaves by LC-MS revealed the presence of a wide variety of substances such as carboxylic acids and terpenes, with flavonoids and fatty acids being more evident. The antifungal assays showed that the extract was not able to inhibit the growth of the tested strains at concentrations with a clinical relevance. However, at higher concentrations, it was able to inhibit the fungal dimorphism of C. albicans and C. tropicalis. It is possible that the T. subulata extract has potential as an inhibitor of fungal virulence factors without affecting the cell viability. Further research should be carried out in order to assess its inhibitory potential for other fungal virulence factors.

The Arylamidine T-2307 as a Novel Treatment for the Prevention and Eradication of Candida tropicalis Biofilms.

Candida tropicalis is an emerging pathogen with a high mortality rate due to its virulence factors, including biofilm formation, that has important repercussions on the public health system. The ability of C. tropicalis to form biofilms, which are potentially more resistant to antifungal drugs and the consequent increasing antimicrobial resistance, highlights an urgent need for the development of novel antifungal. The present study analyzed the antibiofilm capacity of the arylamidine T-2307 on two strains of Candida tropicalis. Antimicrobial activity and time-killing assays were performed to evaluate the anticandidal effects of T-2307, the antibiofilm ability on biomass inhibition and eradication was evaluated by the crystal violet (CV) method. Furthermore, in Galleria mellonella infected larvae an increased survival after pre-and post- treatment with T-2307 was observed. The MTT test was used to determine the viability of immortalized human prostate epithelial cells (PNT1A) after exposure to different concentrations of T-2307. Levels of interleukin IL-4, IL-8, IL-10 were quantified after Candida infection of PNT1A cells and treatment. Active doses of T-2307 did not affect the viability of PNT1A cells, and drug concentrations of 0.005 or 0.01 µg mL-1 inhibited the secretion of inflammatory cytokines. Taken together, these results provide new information on T-2307, indicating this drug as a new and promising alternative therapeutic option for the treatment of Candida infections.

N,N-dimethyl chitosan oligosaccharide (DMCOS) promotes antifungal activity by causing mitochondrial damage

By modifying chitosan oligosaccharide (COS) with the Eschweiler-Clarke reaction, the chitosan oligosaccharide derivative DMCOS was synthesized. FT-IR, 1D and 2D NMR spectra, MALDI-ToF MS, and elemental analysis were applied to analyze the structure of DMCOS, which revealed that the primary amines were converted into tertiary amines after methylation. DMCOS displayed less thermal stability than COS. In comparison to COS, it was discovered that DMCOS possessed more potent antimicrobial activity against four bacterial strains (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) and three yeast strains (Candida albicans, Candida tropicalis, and Candida parapsilosis). The antioxidant studies indicated that DMCOS had less antioxidant activity than COS. Consequently, ROS level elevated in C. albicans cells following treatment with DMCOS, which decreased mitochondrial membrane potential. It was recalled that DMCOS may kill C. albicans by causing mitochondrial damage. In addition, DMCOS was demonstrated to be non-cytotoxic.

Probiotic Potentials of Lactic Acid Bacteria and Yeasts from Raw Goat Milk in Nigeria.

Probiotic microorganisms are incorporated in foods due to their numerous health benefits. We investigated lactic acid bacteria (LAB) and yeasts isolated from goat milk in Nigeria for novel probiotic strains. In this study, a total of 27 LAB and 23 yeast strains were assessed for their probiotic potentials. Only six LAB strains (Weissella cibaria GM 93m3, Weissella confusa GM 92m1, Pediococcus acidilactici GM 18a, Pediococcus pentosaceus GM 23d, Lactiplantibacillus pentosus GM 102s4, Limosilactobacillus fermentum GM 30m1) and four yeast strains (Candida tropicalis 12a, C. tropicalis 33d, Diutina rugosa 53b, and D. rugosa 77a) identified using partial 16S and 26S rDNA sequencing, respectively, showed survival at pH 2.5, 0.3% bile salt, and simulated gastrointestinal conditions and possessed auto-aggregative and hydrophobic properties, thus satisfying key in vitro criteria as probiotics. All LAB strains showed coaggregation properties and antimicrobial activities against pathogens. Pediococcus pentosaceus GM 23d recorded the strongest coaggregation percentage (34-94%) against 14 pathogens, while W. cibaria GM 93m3 showed the least (6-57%) against eight of the 14 pathogens. The whole cell and extracellular extracts of LAB and yeast strains, with the exception of D. rugosa 77a, had either 2,2-diphenyl-1-picryl-hydrazyl and/or hydroxyl radical scavenging activity. In conclusion, all six LAB and four yeast strains are important probiotic candidates that can be further investigated for use as functional starter cultures.

Comparative metabolic analysis of the adaptive Candida tropicalis to furfural stress response

The novel tolerant strain Candida tropicalis Y31-N (Y31-N) with the high tolerance against furfural was obtained by the continuous domestication processes from the parent strain Candida tropicalis Y-3 (Y-3). The xylitol yield was increased by more than 84.8% with the Y31-N, as well as the furfural consumption at about five-times rate than the Y-3. The Y31-N was able to control the cells membrane fluidity by regulating the composition of the fatty acids in cells, thus maintaining the integrity of cells membrane function to resist furfural stress, and could produce more ATP and NAD(P)H rapidly through the metabolic rearrangement to alleviate the furfural stress, compared to the Y-3. Moreover, several genes related to trehalose synthesis, GABA metabolism and NADPH production were verified to be essential for resistance to furfural by single-gene knockout. It provided a broader understanding of the mechanisms of furfural tolerance and prospective evidence for the further metabolic engineering.

Anti-Candida activity and industrial properties of Pediococcus pentosaceus NOA-2142 isolate from traditional pickled gherkin

Antifungal activities of LAB have increased in many environments, especially in foods, due to the harms of chemical preservatives, as they are natural and capable of preventing both spoilage and infections. This antifungal activity is associated with metabolic compounds of LAB such as cyclic dipeptides, fatty acids, hydrogen peroxide, organic acids, and phenyl lactic acid (PLA) which are produced directly or indirectly. On the other hand, many Candida sp. such as Candida albicans is an opportunistic pathogen and can cause diseases ranging from superficial mucosal to life-threatening systemic infections, and spoilage in food. Therefore, the anti-candida activity of LAB is an important issue. In this study, it was aimed to reveal the anti-candida activity of Pediococcus pentosaceus NOA-2142 which isolated from a traditional pickled gherkin, and to investigate the industrial properties of this strain for widespread use. In the study, the NOA-2142 isolate was selected for its high anti-candida activity, and was determined to belong to P. pentosaceus species. Subsequently, the minimum inhibitory concentration (MIC) of the cell-free supernatant (CFS) of this isolate against pathogen strains of Candida albicans and Candida tropicalis was determined as 1/128 and 1/64, respectively. In addition, the D-3-phenyllactic acid content, which is the most likely cause of the anti-candida activity of the CFS, was determined as 163.21 mg/L. Moreover, the isolate were revealed to have the ability to grow at temperatures of 15oC and above, and in the range of 3–12% NaCl concentration and 3.0–9 pH value. The NOA-2142 isolate showed the highest susceptibility with 40.53 mm zone diameter to the clindamycin antibiotic disc. As a result, the P. pentosaceus NOA-2142 with antifungal potential could be a proper candidate as bio-preservative starter or adjunct culture, or the CFS of P. pentosaceus NOA-2142 could be used as a natural additive.

Detection of spoilage-causing yeasts and bacteria in tchapalo, the Ivorian traditional sorghum beer.

In this study, we aimed to analyse the spoilage potential of the isolated yeast, LAB and AAB species. Thus, 11 strains were inoculated at 0·3% (v/v) into a sterile filtered tchapalo and stored for 3 days at ambient temperature (27-30°C). All the tested strains grew well or remained stable except for Limosilactobacillus fermentum and Pediococcus acidilactici, which decreased throughout the storage time. A significant decrease of total soluble solids was observed only for Saccharomyces cerevisiae (from 7·8 to 5·8 °Brix) and Meyerozyma guilliermondii (from 7·8 to 5·5 °Brix). The tchapalo samples inoculated with the LAB strains Weissella paramesenteroides, P. acidilactici, L. fermentum and the yeast strain Candida tropicalis were judged similar to the control by the panellists. However, the strains of Lacticaseibacillus paracasei and Latilactobacillus curvatus (LAB), S. cerevisiae, M. guilliermondii and Kluyveromyces marxianus (yeasts) and Acetobacter pasteurianus and A. cerevisiae (AAB) induced the spoilage of the tchapalo appearance, smell and/or taste. In the spoiled tchapalo quantitative and qualitative modification of some volatile compounds (VOCs), such as lilac aldehyde, ethyl acetate, ethyl hexanoate, ethyl octanoate and phenethyl acetate, were observed. These results provide information about the microorganisms that need to be removed to extend the shelf life of tchapalo.