Lag Phase Of Growth Research Articles

Expanding the product portfolio of carbon dioxide and hydrogen-based gas fermentation with an evolved strain of Clostridium carboxidivorans

CO2:H2-based gas fermentation with acetogenic Clostridium species are at an early stage of development. This work exploited the Adaptive Laboratory Evolution technique to improve the growth of C. carboxidivorans P7 on CO2 and H2. An adapted strain with decreased growth lag phase and improved biomass production was obtained. Genomic analysis revealed a conserved frameshift mutation in the catalytic subunit of the hexameric hydrogenase gene. The resulted truncated protein variant, most likely lacking its functionality, suggests that other hydrogenases might be more efficient for H2-based growth of this strain. Furthermore, the adapted strain generated hexanol as primary fermentation product. For the first time, hexanol was produced directly from CO2:H2 blend, achieving the highest maximum productivity reported so far via gas fermentation. Traces of valerate, pentanol, eptanol and octanol were observed in the fermentation broth. The adapted strain shows promising to enrich the product spectrum targetable by future gas fermentation processes.

Phenotypic and comparative transcriptomics analysis of RDS1 overexpression reveal tolerance of Saccharomyces cerevisiae to furfural

The yeast Saccharomyces cerevisiae able to tolerate lignocellulose-derived inhibitors like furfural. Yeast strain performance tolerance has been measured by the length of the lag phase for cell growth in response to the furfural inhibitor challenge. The aims of this work were to obtain RDS1 yeast tolerant strain against furfural through overexpression using a method of invivo homologous recombination. Here, we report that the overexpressing RDS1 recovered more rapidly and displayed a lag phase at about 12h than its parental strain. Overexpressing RDS1 strain encodes a novel aldehyde reductase with catalytic function for reduction of furfural with NAD(P)H as the co-factor. It displayed the highest specific activity (24.8 U/mg) for furfural reduction using NADH as a cofactor. Fluorescence microscopy revealed improved accumulation of reactive oxygen species resistance to the damaging effects of inhibitor in contrast to the parental. Comparative transcriptomics revealed key genes potentially associated with stress responses to the furfural inhibitor, including specific and multiple functions involving defensive reduction-oxidation reaction process and cell wall response. A significant change in expression level of log2 (fold change >1) was displayed for RDS1 gene in the recombinant strain, which demonstrated that the introduction of RDS1 overexpression promoted the expression level. Such signature expressions differentiated tolerance phenotypes of RDS1 from the innate stress response of its parental strain. Overexpression of the RDS1 gene involving diversified functional categories is accountable for stress tolerance in yeast S.cerevisiae to survive and adapt the furfural during the lag phase.

Predictive model for growth of Pseudomonas spp. on fresh duck breast as a function of temperature

This study was performed to develop a predictive growth model of Pseudomonas spp. to ensure the safety of fresh duck breast. Sterile fresh duck breasts were inoculated with Pseudomonas spp. and stored at 4°C, 10°C, 15°C, 20°C, 25°C, and 30°C to measure the microbial change. The Baranyi primary model was used to simulate the growth changes of Pseudomonas spp. at different temperatures. The square root type model and hyperbolic function as secondary models were used to model the effect of temperature on the maximum specific growth rate and lag phase duration. The results showed that the primary models fitted the growth data well (all R2 > 0.900 and RMSE were close to 0). In validation study of secondary model, R2 were 0.987 and 0.925, RMSE were 0.017 and 1.825, respectively, indicating that the parameters of primary models were accurately predicted by secondary models. The validation experiments at tested temperatures proved that the changes of Pseudomonas spp. could be predicted accurately by the developed models combining primary and secondary models both at constant and variable temperatures. The model could be applied to predict the growth of Pseudomonas spp. in logistics for avoiding microbial spoilage on fresh duck breast.

TMT-based quantitative proteomic and scanning electron microscopy reveals biological and morphological changes of Staphylococcus aureus irradiated by electron beam

Electron beam irradiation is an efficient cold sterilization technique that has been widely utilized in food preservation. To understand the biological and morphological changes of microorganisms by electron beam irradiation, the D10 value, growth curve, and morphological characterization by scanning electron microscope (SEM) of Staphylococcus aureus were studied. Furthermore, Tandem mass tag (TMT)-based quantitative proteomic was performed to investigate the responses of Staphylococcus aureus to electron beam. The results showed that electron beam prolonged the lag phase of bacterial growth, and irradiated bacteria were more sensitive to irradiation than unirradiated bacteria. Compared to unirradiated cells, there were 53, 96, 1055, and 431 differentially expressed proteins (DEPs) detected in 1-kGy and 2-kGy irradiated cells after 0 h and 24 h incubation, respectively. Most of the DEPs involved in DNA repair were found to be up-regulated, whereas those involved in biofilm formation and staphylococcal enterotoxin production were down-regulated. No noticeable morphological changes were observed in irradiated S. aureus. These findings provided valuable information in the responses of S. aureus to electron beam irradiation, leading to a better understanding of the effects of electron beam irradiation on food pathogens.

Contribution of YPRO15C Overexpression to the Resistance of Saccharomyces cerevisiae BY4742 Strain to Furfural Inhibitor.

Lignocellulosic biomass is still considered a feasible source of bioethanol production. Saccharomyces cerevisiae can adapt to detoxify lignocellulose-derived inhibitors, including furfural. Tolerance of strain performance has been measured by the extent of the lag phase for cell proliferation following the furfural inhibitor challenge. The purpose of this work was to obtain a tolerant yeast strain against furfural through overexpression of YPR015C using the in vivo homologous recombination method. The physiological observation of the overexpressing yeast strain showed that it was more resistant to furfural than its parental strain. Fluorescence microscopy revealed improved enzyme reductase activity and accumulation of oxygen reactive species due to the harmful effects of furfural inhibitor in contrast to its parental strain. Comparative transcriptomic analysis revealed 79 genes potentially involved in amino acid biosynthesis, oxidative stress, cell wall response, heat shock protein, and mitochondrial-associated protein for the YPR015C overexpressing strain associated with stress responses to furfural at the late stage of lag phase growth. Both up- and down-regulated genes involved in diversified functional categories were accountable for tolerance in yeast to survive and adapt to the furfural stress in a time course study during the lag phase growth. This study enlarges our perceptions comprehensively about the physiological and molecular mechanisms implicated in the YPR015C overexpressing strain's tolerance under furfural stress. Construction illustration of the recombinant plasmid. a) pUG6-TEF1p-YPR015C, b) integration diagram of the recombinant plasmid pUG6-TEF1p-YPR into the chromosomal DNA of Saccharomyces cerevisiae.

Optimization and enhancement of biohydrogen production in a single-stage hybrid (dark/photo) fermentation reactor using Fe3O4 and TiO2 nanoparticles

The utilization of nanoparticles to enhance bacterial activity and boost hydrogen production in fermentation processes has gained significant attention due to their unique properties such as high specific surface area and quantum size. This research aimed to improve the biohydrogen yield from food waste by adding iron oxide nanoparticles (Fe3O4) at various concentrations (50, 75, 100, 150, and 200 mg/l) and titanium dioxide (TiO2) at different amounts (25–150 mg/l) to a single-stage hybrid (dark/photo) fermentation reactor. After obtaining the optimal amount of these two nanoparticles, the effect of synergic addition of nanoparticles on hydrogen production yield, was investigated at ratios of Fe3O4/TiO2 = 50/50 and 100/50 mg/mg. At the ratio of Fe3O4/TiO2 = 100/50, the cumulative hydrogen production and yield of hydrogen have increased from 1613 to 3392 ml and 101.60 to 213.66 mlH2/gVS, respectively, compared to the control experiment. We also found that the COD removal rate has enhanced from 28% to 40.1%. In the optimal value, the bacterial growth lag phase has also remarkably decreased from 8.19 to 4.81 h.

Assessment of the relationship between the MLST genetic diversity of Listeria monocytogenes and growth under selective and non-selective conditions

Listeria monocytogenes can grow under stressful conditions and contaminate various food categories. Progresss in DNA sequencing-based identification methods, such as multi-locus sequence typing (MLST) now allow for more accurate characterization of pathogens. L. monocytogenes MLST genetic diversity is reflected by the different prevalence of the “clonal complexes” (CCs) in foods or infections. Better understanding of the growth potentials of L. monocytogenes is essential for quantitative risk assessment and efficient detection across CCs genetic diversity. Using optical density measurements taken with an automated spectrophotometer, we compared the maximal growth rate and lag phase of 39 strains from 13 different CCs and various food origins, in 3 broths mimicking stresful food conditions (8 °C, aw 0.95 and pH5) and in ISO Standard enrichment broths (Half Fraser and Fraser). This is important as growth could influence risk through pathogen multiplication in food. Besides, enrichment problems could lead to a lack of detection of some CCs. Despite small differences highlighting natural intraspecific variability, our results show that growth performances of L. monocytogenes strains under the conditions tested in selective and non-selective broth do not appear to be strongly correlated to CCs and cannot explain higher CC “virulence” or prevalence.

Effects of Water Potential on Anaerobic Methane Production and a Microbial Consortium

This study probed the effect of the water potential (Ψ) on anaerobic methane production and a microbial consortium. The Ψ level of the investigated anaerobic digester (n = 20) was in the range from −0.10 to −2.09 MPa with a mean value of −1.23 MPa, and the Ψ level of the anaerobic digester was significantly correlated with the SCOD, TKN, NH4+-N, alkalinity, salinity (SPS), NH4+, Na+, K+, Cl−, NO3−, and PO43− (p < 0.001). The maximum methane production rate (Rm) of the Control (−0.40 MPa) was 8.11 mL day−1 and decreased to 1.70 mL day−1 at −3.91 MPa (K5), and the lag growth phase time (λ) was delayed to 35.96 and 25.34 days at −2.85 MPa (K4) and −3.91 MPa (K5), respectively. The ultimate methane potential (Bu) was 0.264 Nm3 kg−1-VSadded for the Control, and when Ψ was adjusted, Bu increased to 0.278 Nm3 kg−1-VSadded at −1.49 MPa (K3) but decreased to 0.203 and 0.172 Nm3 kg−1-VSadded at −2.85 MPa (K4) and −3.91 MPa (K5), respectively. Therefore, the methane yield was inhibited due to the decrease in Ψ, and the methane yield is predicted to be inhibited from about −1.65 MPa. In the genus-level taxonomic classification of the microbial community, the relative abundance of Methanosarcina decreased significantly to 36.76% at −3.91 MPa (K5) compared to 58.15% for the Control; however, the relative abundance of Methanoculleus significantly increased to 35.16% at −3.91 MPa (K5) compared to 14.85% for the Control.

Changes in the metabolome of probiotics during the stationary phase increase resistance to lyophilization

In the probiotics manufacturing process, lyophilization damages the cell membrane of microorganisms, reducing their viability and delaying reactivation of their cellular metabolism. The growth phase of microorganisms at the time of lyophilization is thought to significantly affect their viability during storage and reactivation in the intestine. However, no study has systematically investigated the differences in overcoming mechanisms in microorganisms harvested at different growth phases against lyophilization. Therefore, in this study, we comparatively assessed the resistance mechanism of Bifidobacterium animalis ssp. lactis and Lacticaseibacillus rhamnosus harvested at exponential and stationary growth phases. We found that B. animalis ssp. lactis and L. rhamnosus harvested at the stationary phase had shorter lag phase in growth and higher survival rates during storage than those harvested at the exponential phase. As a result of metabolome analysis, the cells harvested at the stationary phase accumulated trehalose and arabinose, which function as cryoprotectants and protect cells from lyophilization-induced damage. These findings could provide a basis for establishing a manufacturing protocol for lyophilized probiotics that can be rapidly reactivated in the intestine to achieve optimal metabolic activity and induce health benefits.

Effects of sulfur and phosphorus concentration on the lipid accumulation and fatty acid profile in Chlorella vulgaris (Chlorophyta).

Nutrient deficiency induces a variety of cellular responses, including an increase in lipid accumulation in microalgae. Nitrogen starvation is the most studied deprivation. Here, we determine the effects of phosphorus and sulfur limitation on lipid accumulation in Chlorella vulgaris. A set of 9 experiments were performed, varying the initial concentration of these nutrients (set to 0, 50, and 100% of their original composition in Bold's basal medium). According to our results, the variation of P and S modified the specific growth rate, lag phase, and cell generation time. The ratio of 50%P and 0%S significantly increased the total lipid concentration. The fatty acid profile was dominated by C16:0, C18:0, and C18:1; a considerable increase in C20:5 was observed with 0%P and 50%S and 0%P and 100%S. Regarding neutral lipids, the response surface methodology (RSM) indicates that the maximum was observed when S was between 40 and 60% and P was between 95 and 100%. Therefore, the enhanced production of lipids caused by P and S limitation may contribute to the efficient oil production useful for algal biofuels.

Деструкция фталевых кислот штаммом Paenarthrobacter sp. SA101, выделенным из сточных вод химического предприятия

Phthalic and terephthalic acids (PA and TPA) are widely used in the chemical industry as plasticizers, for the production of polymer materials, and therefore are common eco-pollutants. The ability of the strain Paenarthrobacter sp. SA101, isolated from a sample of a chemical plant wastewater (Perm), to growth on high concentrations of PA and TPA was studied. It was shown that strain SA101 is capable of efficient growth on these substrates at concentrations up to 20 g/l, which is shown for the representatives of the genus Paenarthrobacter for the first time. Higher strain growth parameters were recorded in media with PA, than in media with TPA: the maximum value of OD600 (1.64), the highest specific growth rate (0.073±0.003 h-1) and the shortest lag phase were observed in a medium with 10 g/l of PA. The highest specific growth rate (0.04±0.002 h‑1) and the maximum value of OD600 (1.6) were observed with 20 g/l of TPA, however, the lag phase of growth was longer than in the medium with 10 g/l of TPA. The strain SA101 was able to utilize 76% of PA in 39 hours and 74.2% of TPA in 71 hours of cultivation, when using these substrates at a concentration of 10 g/l. The cells of the strain SA101 contain a plasmid with a molecular weight of ~ 100 bp. The strain SA101 is promising for the development of biotechnological methods for cleaning phthalate-contaminated soils and industrial effluents.

Growth Study and Biological Hydrogen Production by novel strain Bacillus paramycoides

Industrial revolution has created high dependent on fossil fuels for energy creation. However, combustion of fossil fuels has created excessive amount of greenhouse gases, hence led to climate change. Thus, renewable energy has been proposed to alleviate the environmental pollution issues around the globe. One of the promising renewable energies is green hydrogen energy. Commercialized technologies such as electrolysis and thermochemical reaction are utilized to form hydrogen energy. Nonetheless, these processes require high energy and yet producing greenhouse gases that harm the environment. In this study, biodegradation process to produce hydrogen energy has been explored. To our knowledge, Bacillus paramycoides strain has not yet been investigated for biological hydrogen evolution. Therefore, in this paper, the ability of Bacillus paramycoides to produce biological hydrogen has been studied. The rod-shaped and gram-positive Bacillus paramycoides was identified under scanning electron microscope and gram staining procedure. Furthermore, biological hydrogen generation by Bacillus sp. was experimented for 96 hours. The result shows that 4668 ± 120 ppm cumulative hydrogen gas was generated through dark fermentation process. For Bacillus sp. growth study, lag, log, and stationary phase have been achieved in 96 hours. In a summary, metabolic engineering to degrade abundant biomass wastes is a sustainable pathway to produce hydrogen energy, simultaneously resolve waste management issue around the globe.

Metal Carbide Nanocrystal Nucleation and Growth in a Transition Metal Coordination Polymer

The mechanism that governs the conversion of the Co-Prussian blue analogue (PBA) to Co2C was investigated and observed to exhibit lag phase growth behavior that can be fit to the autocatalytic kinetic model. The energetics and activation energies were extracted from the temperature-dependent data. The experimental results provide insight into how to control the size and crystallinity of Co2C, where shorter lag times and smaller sizes occur at higher reaction temperatures and longer times and larger sizes at lower temperatures. Investigation of temperature-dependent growth revealed an R2 relationship, supporting a surface mediated growth model. In addition, low temperatures lead to higher polycrystallinity in the nanocrystal that grows within the PBA framework.

Phototroph-heterotroph interactions during growth and long-term starvation across Prochlorococcus and Alteromonas diversity

Due to their potential impact on ecosystems and biogeochemistry, microbial interactions, such as those between phytoplankton and bacteria, have been studied intensively using specific model organisms. Yet, to what extent interactions differ between closely related organisms, or how these interactions change over time, or culture conditions, remains unclear. Here, we characterize the interactions between five strains each of two globally abundant marine microorganisms, Prochlorococcus (phototroph) and Alteromonas (heterotroph), from the first encounter between individual strains and over more than a year of repeated cycles of exponential growth and long-term nitrogen starvation. Prochlorococcus-Alteromonas interactions had little effect on traditional growth parameters such as Prochlorococcus growth rate, maximal fluorescence, or lag phase, affecting primarily the dynamics of culture decline, which we interpret as representing cell mortality and lysis. The shape of the Prochlorococcus decline curve and the carrying capacity of the co-cultures were determined by the phototroph and not the heterotroph strains involved. Comparing various mathematical models of culture mortality suggests that Prochlorococcus death rate increases over time in mono-cultures but decreases in co-cultures, with cells potentially becoming more resistant to stress. Our results demonstrate intra-species differences in ecologically relevant co-culture outcomes. These include the recycling efficiency of N and whether the interactions are mutually synergistic or competitive. They also highlight the information-rich growth and death curves as a useful readout of the interaction phenotype.

Comparison of predictive growth models for Bacillus cereus in cooked and fried rice during storage

This study aimed to develop and compare growth models of Bacillus cereus in cooked and fried rice. A cocktail of B. cereus was inoculated into cooked and fried rice to obtain an initial concentration of ca. 2 log CFU g-1 and stored at 13, 30, 42, and 60oC. The cell concentration of B. cereus during storage were fitted to the primary models of Baranyi, Huang, and modified Gompertz. The maximum specific growth rates (µmax) were fitted to the Ratkowsky model, while the lag phase was fitted using the first-order polynomial model. There was no significant difference (p>0.05) in the µmax and lag phase of B. cereus in cooked rice or fried rice at 13 and 30oC. However, at 42oC the µmax in fried rice was significantly higher (p<0.05) and the lag phase was significantly longer (p<0.05) than those in cooked rice. No growth was observed at 60oC. The Baranyi model showed the best performance in fitting the µmax of B. cereus in cooked and fried rice. The validation study confirmed that the Ratkowsky and the first-order polynomial model could satisfactorily fit the µmax and the lag phase, respectively. Modeling of B. cereus growth in cooked and fried rice can use the primary model of Baranyi fitted to the secondary model of Ratkowsky and first-order polynomial to predict the growth rate and lag phase, respectively. The model suggests that B. cereus grows significantly faster in fried rice at 42oC.

Comparison of enrichment methods for isolating Enterohemorrhagic Escherichia coli in kimchi

This study was conducted to compare the efficiency of four enrichment methods of Enterohemorrhagic Escherichia coli by using the 16S rRNA amplicon sequencing and a predictive model. Four different methods (US FDA, ISO, Japan Food Hygiene Association and Korea Ministry of Food and Drug Safety) were used to enrich EHEC in kimchi inoculated with cocktails of EHEC strains (NCCP 13720, NCCP 13721, and NCCP 14134). The maximum growth rate (μmax) and lag phase duration (LPD) were compared using the Baranyi model, and 16S rRNA targeted sequencing was performed with samples at the end of the exponential phase. As a result, the μmax and LPD values of Baranyi model developed for the four enriched media ranged from 0.82 to 0.92 and from 2.35 to 2.68, respectively, suggesting that the growth of EHEC was similar in all four enrichment media. As for the relative abundance of the bacterial composition at the family level, Enterobacteriaceae was identified as the major component (>50%) in all four enriched media. The relative abundance of Enterobacteriaceae was highest (>90%) in the two enriched media with 20 mg/L novobiocin, demonstrating that significant growth of non-targeted bacteria takes place in enrichment broths utilizing <20 mg/L novobiocin or different antibiotics. In conclusion, this study suggests that all four enrichment broth are suitable for growing EHEC in kimchi and the use and concentration of antibiotics such as novobiocin in enrichment media may have a critical role in species diversity.

Effects of Inhibitors Generated by Dilute Phosphoric Acid Plus Steam-Exploded Poplar on Saccharomyces cerevisiae Growth

The pretreatment of lignocellulosic biomass is important for efficient bioethanol conversion, but causes undesirable by-products that inhibit microbial growth, conversely affecting the bioconversion efficiency. In this study, the main inhibitors derived from dilute phosphoric acid plus steam-exploded poplar wood were identified as 0.22 g/L furfural, 3.63 g/L acetic acid, 0.08 g/L syringaldehyde, etc., indicating the green nature and low toxicity of the pretreatment process. The effects of the three typical inhibitors (furfural, acetic acid, and syringaldehyde) on Saccharomyces cerevisiae 1517RM growth were analyzed and shown to prolong the lag phase of microbial growth to different degrees. In all the inhibitor groups, the ergosterol secretion was boosted, indicating low cell membrane fluidity and robustness of the strain to an adverse environment. The cell electronegativity and morphology of S. cerevisiae 1517RM also changed under different growth conditions, which was helpful for monitoring the physicochemical properties of cells. Furfural, acetic acid, and syringaldehyde had a synergistic effect on each other, providing an important reference to improving the subsequent ethanol fermentation process.

Metabolite-Based Mutualistic Interaction between Two Novel Clostridial Species from Pit Mud Enhances Butyrate and Caproate Production.

Pit mud microbial consortia play crucial roles in the formation of Chinese strong-flavor baijiu's key flavor-active compounds, especially butyric and caproic acids. Clostridia, one of the abundant bacterial groups in pit mud, were recognized as important butyric and caproic acid producers. Research on the interactions of the pit mud microbial community mainly depends on correlation analysis at present. Interaction between Clostridium and other microorganisms and its involvement in short/medium-chain fatty acid (S/MCFA) metabolism are still unclear. We previously found coculture of two clostridial strains isolated from pit mud, Clostridium fermenticellae JN500901 (C.901) and Novisyntrophococcus fermenticellae JN500902 (N.902), could enhance S/MCFA accumulation. Here, we investigated their underlying interaction mechanism through the combined analysis of phenotype, genome, and transcriptome. Compared to monocultures, coculture of C.901 and N.902 obviously promoted their growth, including shortening the growth lag phase and increasing biomass, and the accumulation of butyric acid and caproic acid. The slight effects of inoculation ratio and continuous passage on the growth and metabolism of coculture indicated the relative stability of their interaction. Transwell coculture and transcriptome analysis showed the interaction between C.901 and N.902 was accomplished by metabolite exchange, i.e., formic acid produced by C.901 activated the Wood-Ljungdahl pathway of N.902, thereby enhancing its production of acetic acid, which was further converted to butyric acid and caproic acid by C.901 through reverse β-oxidation. This work demonstrates the potential roles of mutually beneficial interspecies interactions in the accumulation of key flavor compounds in pit mud. IMPORTANCE Microbial interactions played crucial roles in influencing the assembly, stability, and function of the microbial community. The metabolites of pit mud microbiota are the key to flavor formation of Chinese strong-flavor baijiu. So far, researches on the interactions of the pit mud microbial community have been mainly based on the correlation analysis of sequencing data, and more work needs to be performed to unveil the complicated interaction patterns. Here, we identified a material exchange-based mutualistic interaction system involving two fatty acid-producing clostridial strains (Clostridium fermenticellae JN500901 and Novisyntrophococcus fermenticellae JN500902) isolated from pit mud and systematically elucidated their interaction mechanism for promoting the production of butyric acid and caproic acid, the key flavor-active compounds of baijiu. Our findings provide a new perspective for understanding the complicated interactions of pit mud microorganisms.

(MeOPhSe)2, a synthetic organic selenium compound, inhibits virulence factors of Candida krusei: Adherence to cervical epithelial cells and biofilm formation

BackgroundSystemic candidiasis is produced by Candida albicans or non-albicans Candida species, opportunistic fungi that produce both superficial and invasive infections. Despite the availability of a wide range of antifungal agents for the treatment of candidiasis, failure of therapy is observed frequently, which opens new avenues in the field of alternative therapeutic strategies. MethodsThe effects of p,p′-methoxyl-diphenyl diselenide [(MeOPhSe)2], a synthetic organic selenium (organochalcogen) compound, were investigated on virulence factors of C. krusei and compared with its antifungal effects on the virulence factors related to adhesion to cervical epithelial cell surfaces with C. albicans. Results(MeOPhSe)2, a compound non-toxic in epithelial (HeLa) and fibroblastic (Vero) cells, inhibited the growth in a dose-dependent manner and changed the kinetics parameters of C. krusei and, most importantly, extending the duration of lag phase of growth, inhibiting biofilm formation, and changing the structure of biofilm. Also, (MeOPhSe)2 reduced C. albicans and C. krusei adherence to cervical epithelial cells, an important factor for the early stage of the Candida-host interaction. The reduction was 37.24 ± 2.7 % in C. krusei (p = 0.00153) and 32.84 ± 3.2 % in C. albicans (p = 0.0072) at 20 µM (MeOPhSe)2, and the effect is in a concentration-dependent manner. Surprisingly, the antifungal potential on adhesion was similar between both species, indicating the potential of (MeOPhSe)2 as a promising antifungal drug against different Candida infections. ConclusionOverall, we demonstrated the potential of (MeOPhSe)2 as an effective antifungal drug against the virulence factors of Candida species.

Antifungal potential and biosafety of native plants from the Brazilian Restinga ecosystem

Control of devastating phytopathogens such as the pineapple black rot causing-pathogen fungus, Thielaviopsis ethacetica , remains dependent on synthetic pesticides despite the detrimental implications of such conventional strategies. Here, attempting to identify and develop cleaner and more sustainable tools to control T. ethacetica , we evaluated the fungicidal potential through in vitro antimicrobial assays of Sideroxylon obtusifolium and Annona acutiflora leaf extracts. To ensure the sustainability of these alternative fungicide tools, we evaluated the toxicity and repellent effects of the most promising extracts against the non-target organism honey bees, Apis mellifera . Preliminary results by diffusion plating indicated bioactivity of the fractions ethyl acetate S. obtusifolium and butanol A. acutiflor a on pineapple black rot causing-pathogen. The featured extract of S. obtusifolium reduced the growth rate by 90% and increased the lag phase of the target pathogen. The fungistatic action of both was observed at 6.25 mg/mL concentrations. Fungicidal activity in vitro was detected at 12.5 mg/mL (ethyl acetate S. obtusifolium ) and 25.0 mg/mL (for butanol A. acutiflora ). Polar extract A. acutiflora exerts selective fungistatic activity on pathogen conidia. Both highlight extracts did not kill A. mellifera foragers even when applied at concentrations as high as 10-fold the fungicidal concentration. Honeybee reduced their feeding activities when they had to feed on plant extract-contaminated diets and extracts from S. obtusifolium and repelled honeybees under free choice conditions. Our findings collectively showed that these plant extracts could be helpful alternative fungicide tools to be integrated into managing T. ethacetica infestations in many food and industrial crops. • Plant extracts active against Thielaviopsis ethacetica were identified. • Plant compounds exert a higher pathogen's growth lag phase than itraconazole. • Fungicidal activity was identified at concentrations of 12.5 and 25.0 mg/mL. • Extract of S. obtusifolium caused the lowest mycelial growth rate and repel bees. • Promising extracts at a concentration 10 times MFC did not kill Apis mellifera bees.