Generic composition of fungi in soil aggregates

A structure of fungal flora was studied in aggregates of various diameter in a chernozemic rendzina and a lessivè soil. Aggregate diameter influenced strongly the distribution of fungi such asCephalosporium, Fusarium, Penicillium and sterile mycelia. The percentage of the above fungi changed with changing aggregate diameter as follows:Cephalosporium: 1–3>5–7 >0.5 in lessivè soil and ≤0.5>5–7>1–3 in chernozemic rendzina,Fusarium: ≤0.5>1–3>5–7 in lessivè soil and 5–7>1–3>0.5 in chernozemic rendzina,Penicillium: 5–7>0.5>1–3 in lessivè soil and 1–3>0.5>5–7 in chernozemic rendzina. The effect of aggregate size on the generic composition of fungal flora in the outer and inner parts of the aggregates was weaker than on that in the whole aggregates. This held especially forCephalosporium, Fusarium and sterile mycelia in the outer part of aggregates andPenicillum in the inner one. Moreover, the percentage of some fungi in whole aggregates of both soils was affected byV _a/V _w in the aggregates. Additional effect in lessivè soil aggregates was that of the percentage of pores measuring 0.1–0.05 μm. Some pores affected the contents of some fungi in the outer part of the aggregates of both soils and in the inner one of chernozemic rendzina aggregates.     

Ammonification in soil aggregates: Effect of some physical,physico-chemical and chemical properties

Aggregate diameter affected significantly the intensity of ammonification in chernozemic rendzina but not in lessivē soil. In the latter the process was influenced significantly by the number of microorganisms able to grow on asparagine agar. A high correlation, though not significant at the level of 0.05, was found between the ammonification intensity and the content of pores of radius: 3–1.5, 7.5–5.0, 0.5–0.25 and 0.01–0.005 μm in chernozemic rendzina and those measuring 1.5–0.5, 0.025–0.01, 0.01–0.005 and >7.5 μm in lessivē soil aggregates as well as the percentage of soil particles of 100–50 μm in chernozemic rendzina aggregates and the internal surface area and organic C in aggregates of lessivē soil.     

Microorganisms in a high altitude Glacier Ice in Tibet

Eighty-one strains of viable microorganisms were recovered from 23 samples collected from Ice Core 3 of Malan Glacier (China, 91° 45.3′ E, 35° 48.4′ N) drilled at high altitude (5620 m). All the strains were prokaryotes—75 of bacteria (including spore-forming ones) and 6 of actinomycetes. The characteristic genera differ from those of Arctic and Antarctic ice, in which many fungi and algae are widely distributed; this shows an difference of environmental conditions between Tibet and polar regions. The variation in number and species ofBacillus in different ice core layers implied changes of environmental conditions in the past.     

Soil humic substances affect transport properties of tonoplast vesicles isolated from oat roots

The effect of a low molecular size (<5 KDa) humic fraction, essentially fulvic acids, on microsomal and tonoplast ion-stimulated ATPase activity was studied. After 20 min of pre-incubation with microsomal vesicles from oat roots, humic substances at organic C concentration of up to 0.5 μg cm^-3 increased KCl-stimulated ATPase activity, while they inhibited enzyme activity at higher concentrations. Cl^--stimulated ATPase activity of tightly sealed tonoplast-enriched vesicles was similarly affected by <5 KDa humic substances. This behaviour was not observed when gramicidin D was added to the assay medium. Proton transport by vesicles incubated up to 5 min with <5 KDa humic molecules was affected in a concentration-dependent manner, strongly resembling that observed for ATP hydrolysis, whereas it was severely reduced when the assay conditions were close to those used for measuring ATP hydrolysis (20 min pre-incubation of vesicles with humic substances). The transmembrane electrical potential was negatively affected, irrespective of the concentration of humic molecules. Furthermore, a 15-min pre-incubation strongly reduced the formation of a potential gradient. The size and concentrations of humic substances employed make an interaction with the vacuolar membrane of root cells plausible. The results show that the main target of humic molecules is the electrical membrane potential and suggest a possible way of interference of these naturally occurring substances with the biochemical mechanisms involved in plant mineral nutrition.     

Stigmasterol-driven enhancement of the in vitro multiplication rate for the marubakaido apple rootstock

The treatment of in vitro-grown shoots of the marubakaido apple rootstock with 0.5 μg stigmasterol, an end-pathway sterol of the bifurcated sterol biosynthetic pathway, in 5 μL acetone per shoot led to a significant (p ≤ 0.05) enhancement of the multiplication rate (MR) from 5.1 (shoots treated with 5 μL acetone only) to 10.3. This increase in the MR was due to a significant enhancement of the number of newly formed main shoots suitable for micropropagation purposes (measuring at least 15 mm in length) from 2.6 to 3.3 per explant, and of the number of newly formed primary lateral shoots from 2.2 to 5.0 per explant as well. Shoots treated with stigmasterol at 0.5 and 2.5 μg per shoot presented primary and secondary lateral shoots with significantly (p ≤ 0.05) longer length compared to shoots treated with acetone only. These results provide an insight into the morphological responses of the marubakaido rootstock shoots to the treatment with an end-pathway sterol. To the best of my knowledge, this is the first report on the successful use of stigmasterol for the improvement of a micropropagation system. These results also demonstrate that stigmasterol-induced shoot proliferation is a low-cost and effective way to enhance the in vitro MR for the apple rootstock.     

Three-dimensional endothelial-tumor epithelial cell interactions in human cervical cancers

Summary The purpose of this study is to understand the multicellular interaction between tumor epithelial (TEC) and human umbilical vein endothelial cells (HUVEC). The development of in vitro systems in which to coculture these cells as multicellular aggregates is very critical. Cell lines were established from cervical tumor cells (n=6) and two from HUVEC (n=2) and they were cultured as three-dimensional (3-D) multicellular-cultures using Cytodex-3 microcarrier beads in the rotating wall vessel (RWV). After a 240-h incubation, TEC and HUVEC proliferated exponentially to 4.2×10⁷ and 2.2 × 10⁷ cells/ml, respectively, without requiring a feeder layer; in contrast to the two-dimensional (2-D) cultures that average about 8 × 10⁶ cells/ml. Phase contrast microscopy indicated formation of 3-D aggregates that varied in size from 0.5 to 5 mm. The size of the aggregates (1–5 mm, 6⊋ash;14 microcarriers) increased over time; however, the number of aggregates (0.5–1 mm, 2–5 microcarriers) decreased over a long-term incubation (240 h) because the cells merged to form large clumps. Maximum aggregation was observed with TEC at 120 h and HUVEC at 96 h. The culture of TEC in the absence of HUVEC produced minimal differentiation in contrast to cocultures. The TEC and HUVEC as cocultures in RWV proliferated at an accelerated rate (1.3 × 10⁷ cells/ml, 96 h). The TEC-HUVEC coculture presented tubular structures penetrating the tumor cell masses, forming aggregates larger in size than the monocultures and typically with greater cell mass and number. The cells were viable (trypan blue exclusion) and metabolically active (glucose utilization) until 240 h. These data suggest that RWV provides a new model that allows us to investigate the regulatory factors that govern tumor angiogenesis.     

Is nitrification affected by the diameter and other properties of soil aggregates?

Nitrification was measured in fractions of chernozemic rendzina and lessivē soil differing in aggregate size. In both soils the maximum rates occurred in aggregates between 1 and 3 mm in diameter. The effects of structural and other properties (particle composition, pore-size distribution, surface area, organic C and total N content, ratio of air volume to water volume in aggregates) proved to be insignificant except for the nitrification rate in the lessivē soil, which positively correlated with the fraction of particles between 20 and 50 μm in diameter.     

The Occurrence of Lysogenic Bacteria and Microbial Aggregates in the Lakes of the McMurdo Dry Valleys,Antarctica

The McMurdo Dry Valleys of Antarctica form the coldest and driest ecosystem on Earth. Within this region there are a number of perennially ice-covered (3–6 m thick) lakes that support active microbial assemblages and have a paucity of metazoans. These lakes receive limited allochthonous input of carbon and nutrients, and primary productivity is limited to only 6 months per year owing to an absence of sunlight during the austral winters. In an effort to establish the role that bacteria and their associated viruses play in carbon and nutrient cycling in these lakes, indigenous bacteria, free bacteriophage, and lysogen abundances were determined. Total bacterial abundances (TDC) ranged from 3.80 × 10⁴ to 2.58 × 10⁷ cells mL^–1 and virus-like particle (VLP) abundances ranged from 2.26 × 10⁵ to 5.56 × 10⁷ VLP mL^–1. VLP abundances were significantly correlated (P < 0.05) with TDC, bacterial productivity (TdR), chlorophyll a (Chl a), and soluble reactive phosphorus (SRP). Lysogenic bacteria, determined by induction with mitomycin C, made up between 2.0% and 62.5% of the total population of bacteria when using significant decreases and increases in TDC and VLP abundances, respectively, and 89.5% when using increases in VLP abundances as the sole criterion for a successful induction event. The contribution of viruses released from induced lysogens contributed <0.015% to the total viral production rate. Carbohydrate and protein based organic aggregates were abundant within the water column of the lakes and were heavily colonized by bacteria and VLPs. Alkaline phosphatase activity was detected within the matrix of the aggregates, implying phosphorus deficiency and consortial nutrient exchanges among microorganisms.     

Relationship between dehydrogenase activity and properties of soil aggregates

Studies of dehydrogenase activity in aggregates of chernozemic rendzina and lessivē soil proved that the diameter of aggregates significantly influences the activity of the above enzyme, subject to soil type. There is a significant positive correlation between the above activity and the percentage of particles 100 to 50 μm in aggregates of lessivē soil but not in those of chernozemic rendzina. Dehydrogenase activity is also affected by soil particles of other sizes, some pores in soil aggregates, the ratio of volume of air to water in them, content of total N and organic C as well as the total, external and internal surface areas, but the correlations in these cases are not significant at the level of 0.05.     

好气与淹水条件下水稻土各粒级团聚体有机碳矿化量

采用室内恒温培养法观测了好气和淹水处理下水稻土不同粒级团聚体中有机碳矿化的动态变化.结果表明：两种处理下,各粒级团聚体中有机碳矿化量都表现为培养前期快速下降,培养后期保持相对稳定的趋势.不同粒级团聚体之间有机碳矿化速率存在明显差异,在整个培养过程中,均以1～2 mm粒级团聚体最高,以＜0.053 mm粒级团聚体最低.统计分析表明,不同粒级团聚体中有机碳矿化量变化与有机碳和微生物生物量碳含量呈显著线性相关.好气和淹水处理下对土壤总有机碳累计矿化量贡献最大的是0.25～1 mm粒级团聚体,分别达41.77%和34.11%;好气处理下贡献最小的是0.053 mm粒级团聚体,淹水处理下贡献最小的是1~2 mm粒级团聚体,分别仅为7.8%和6.6%.     

Microbial Succession in a Compost-packed Biofilter Treating Benzene-contaminated Air

Air artificially contaminated with increasing concentrations of benzene was treated in a laboratory scale compost-packed biofilter for 240 days with a removal efficiency of 81–100%. The bacterial community in the packing material (PM) at different heights of the biofilter was analysed every 60 days. Bacterial plate counts and ribosomal intergenic spacer analysis (RISA) of the isolated strains showed that the number of cultivable aerobic heterotrophic bacteria and the species diversity increased with benzene availability. Identification of the isolated species and the main bands in denaturing gradient gel electrophoresis (DGGE) profiles from total compost DNA during the treatment revealed that, at a relatively low volumetric benzene load (1.2≤VBL≤6.4 g m⁻³ _PM h⁻¹), besides low G+C Gram positive bacteria, originally present in the packing compost, bacteroidetes and β- and γ-proteobacteria became detectable in the colonising population. At the VBL value (24.8 g m⁻³ _PM h⁻¹) ensuring the maximum elimination capacity of the biofilter (20.1 g m⁻³ _PM h⁻¹), strains affiliated to the genus Rhodococcus dominated the microflora, followed by β-proteobacteria comprising the genera Bordetella and Neisseria. Under these conditions, more than 35% of the isolated strains were able to grow on benzene as the sole carbon source. Comparison of DGGE and automated RISA profiles of the total community and isolated strains showed that a complex bacterial succession occurred in the reactor in response to the increasing concentrations of the pollutant and that cultivable bacteria played a major role in benzene degradation under the adopted conditions.     

Effects of Cycle Time on Properties of Aerobic Granules in Sequencing Batch Airlift Reactors

Summary The granulation and properties of aerobic sludge were studied in two sequencing batch airlift reactors (SBARs). The synthetic wastewater in the two reactors had initially different levels of COD (400 mg l⁻¹ in R1 and 1600 mg l⁻¹ in R2). A hydraulic cycle time of 3 and 12 h was conducted in the reactors R1 and R2, respectively and the process of granulation was observed by optical microscopy. It was found that the course of granulation at a cycle time of 3 h in R1 was shorter than that at cycle time of 12 h in R2 and the properties of aerobic granules were distinct in the reactors due to the different hydraulic cycle time. Under a cycle time of 3 h, granule diameter was around 1.0–2.0 mm, VSS ratio was 92.08% with stronger granule strength; under a cycle time of 12 h, granule diameter was around 0.5–1.0 mm, VSS ratio was 83.92% with weaker granule strength. In addition, the morphology of microorganisms in granules was obviously dissimilar when the hydraulic cycle time was different. It was concluded that the hydraulic cycle time plays a crucial role in the granulation and properties of aerobic granules. It is expected that the experimental findings will provide useful information on factors affecting aerobic granulation.     

Quantification of the geocarposphere and rhizosphere effect of peanut (Arachis hypogaea L.)

Roots and pods of field-grown peanut (groundnut) (Arachis hypogaea L.) were sampled at the R3, R5, and R7 developmental stages and examined in comparison to root- and pod-free soil for microbial population densities to assess the geocarposphere and rhizosphere effects. G/ S (no. geocarposphere microorganisms/no. soil microorganisms) and R/S (no. rhizosphere microorganisms/no. soil microorganisms) ratios were calculated for total fungi,Asperigillus flavus, spore-forming bacilli, coryneform bacteria, fluorescent pseudomonads, and total bacteria isolated on low- and high-nutrient media. A clear geocarposphere effect was evidenced by increased population densities of bacteria and fungi associated with developing pods compared to soil. G/S and R/S ratios were generally greater than 1.0 for all groups of microorganisms except bacilli. G/S ratios were greater for total bacteria than for total fungi at two of the three sample times, suggesting that bacteria were stimulated more than fungi in the zone around developing pods. In contrast, R/S ratios, were higher for total fungi than for total bacteria at two of three sample times. The preferential association of fungi and bacteria with early developmental stages of the pod indicates that some microorganisms are particularly well adapted for colonization of the peanut geocarposphere. These microorganisms are logical candidates for evaluation as biological control candiates forA. flavus.     

Microdistribution of sulfate-reducing bacteria in sediments of a hypertrophic lake and their response to the addition of organic matter

To clarify the ecological significance of the association of sulfate-reducing bacteria (SRB) with sediment particle size, SRB utilizing lactate (l-SRB), propionate (p-SRB) and acetate (a-SRB) were examined with different sizes of sediment particles in a hypertrophic freshwater lake using the anaerobic plate count method. The numbers ofl-SRB anda-SRB were 10⁴–10⁵ colony forming units (CFU) per ml in the 0–3 cm layer and 10²–10³ CFU ml⁻¹ in the 10–13 cm layer while the numbers ofp-SRB were one or two orders lower than those ofl-SRB anda-SRB. A sediment suspension was fractionated into four fractions (<1, 1–10, 10–94 and >94 μm). The highest proportions ofl-SRB anda-SRB were found in the 10–94 μm fraction: 66–97% forl-SRB and 53–98% fora-SRB. The highest proportion ofp-SRB was found in the >94 μm fraction (70–74%). These results indicate that most SRB were associated with sediment particles. One isolate from an acetate-utilizing enrichment culture was similar toDesulfotomaculum acetoxidans, a spore-forming sulfate-reducing bacterium. When lactate and sulfate were added to sediment samples,l-SRB anda-SRB in the <10 μm-fraction grew more rapidly than those in whole sediment for the first 2 days. This result suggests that nutrients uptake by free-living and small particle-associated (<10 μm) SRB is higher than that by SRB associated with larger particles.     

Hypolithic Cyanobacteria, Dry Limit of Photosynthesis, and Microbial Ecology in the Hyperarid Atacama Desert

The occurrence of hypolithic cyanobacteria colonizing translucent stones was quantified along the aridity gradient in the Atacama Desert in Chile, from less arid areas to the hyperarid core where photosynthetic life and thus primary production reach their limits. As mean rainfall declines from 21 to ≤2 mm year⁻¹, the abundance of hypolithic cyanobacteria drops from 28 to <0.1%, molecular diversity declines threefold, and organic carbon residence times increase by three orders of magnitude. Communities contained a single Chroococcidiopsis morphospecies with heterotrophic associates, yet molecular analysis revealed that each stone supported a number of unique 16S rRNA gene-defined genotypes. A fivefold increase in steady-state residence times for organic carbon within communities in the hyperarid core (3200 years turnover time) indicates a significant decline in biological carbon cycling. Six years of microclimate data suggest that the dry limit corresponds to ≤5 mm year⁻¹ rainfall and/or decadal periods of no rain, with <75 h year⁻¹ of liquid water available to cyanobacteria under light conditions suitable for photosynthesis. In the hyperarid core, hypolithic cyanobacteria are rare and exist in small spatially isolated islands amidst a microbially depauperate bare soil. These findings suggest that photosynthetic life is extremely unlikely on the present-day surface of Mars, but may have existed in the past. If so, such microhabitats would probably be widely dispersed, difficult to detect, and millimeters away from virtually lifeless surroundings.     

In Vitro Antibacterial Activity of 4-Phenyl-1-(2-phenyl-allyl)pyridinium bromide: A Novel Class of Pyridinium Based Antibacterial Compounds

The continuing increase in the incidence of multi drug resistant pathogenic bacteria and shortage of new antimicrobial agents are the prime driver in efforts to identify the novel antimicrobial classes. In vitro antibacterial activity of 4-phenyl-1-(2-phenylallyl) pyridinium bromide was tested against Gram positive Staphylococcus aureus, Streptococcus species, Bacillus subtilis, and Gram negative Klebsiella aerogenes and Escherichia coli using disk diffusion method. Among them S. aureus showed strong antibacterial activity (21.99 ± 0.03 mm) while E. coli showed very little activity (8.97 ± 0.06 mm) towards the compound. The MIC of 4-phenyl-1-(2-phenyl-allyl)-pyridinium bromide for 90% S. aureus was ≤20 μg/ml and was compared with phenoxymethylpenicillin, cloxacillin, erythromycin and vancomycin. When 4-phenyl-1-(2-phenyl-allyl)pyridinium bromide showed MIC at ≤20 μg/ml, all others showed MIC at ≤100 μg/ml. Strong antibacterial activity of 4-phenyl-1-(2-phenyl-allyl)pyridinium bromide against S. aureus indicates that there is a possibility to use it as an effective antibacterial agent.     

Phylogenetic Diversity and Axial Distribution of Microbes in the Intestinal Tract of the Polychaete <Emphasis Type="Italic">Neanthes glandicincta</Emphasis>

The phylogenetic diversity and axial distribution of microorganisms in three sections of the gastrointestinal tracts of the polychaete Neanthes glandicincta was evaluated using both most probable number method and cloning analyses of 16S rRNA genes in this study. Quantification of the density of microorganisms in the gut showed that aerobic microorganisms decreased from anterior to posterior, while anaerobic ones showed a reverse trend. The total numbers of microorganisms decreased significantly (p < 0.05, analysis of variance) but more rapidly from the anterior to the middle segment. Phylogenetic analysis showed that the dominating phylogenetic groups included Methanomicrobiales I: Methanosaetaceae (up to 66% of archaeal clones), δ-Proteobacteria (up to 42% of bacterial clones), and γ-Proteobacteria (up to 30% of bacterial clones) widely distributed throughout the entire gut. Other microbiota distributed in different gut sections were Methanomicrobiales II: Methanospirillaceae, Methanomicrobiales III, Thermoplasmatales, Crenarchaea, Methanobacteriaceae, and Methanosarcinales for archaea; and α-Proteobacteria, β-Proteobacteria, Fusobacteria, Clostridia, Chloroflexi, and Planctomycetes for bacteria. The results reveal a difference in microbial community structure along the gut of N. glandicincta. The various phylogenetic diversity and axial distribution of microbes along the gut might indicate an environmental gradient from anterior to posterior sections affecting the structure of the microbial community.     

Response of denitrification rate associated with wetting and drying cycles in a littoral wetland area of Lake Biwa,Japan

To clarify the relationship between denitrification activity and dry–wet levels in the littoral wetland sediments of Lake Biwa, Japan, denitrification rates and their regulating parameters (degree of dryness, redox potential, nitrate concentration) were measured on different moisture sediments. Redox potential in sediments was higher in the exposed region in contact with atmosphere than the flooded region covered with water. The nitrate concentration in interstitial waters was undetectable in the flooded region. On the other hand, concentration in the exposed region increased with increase in the degree of sediment dryness. The denitrification rate ranged from <0.001 to 0.88 μg N cm⁻³ h⁻¹ in the exposed region and increased with the increase in the degree of dryness. In the flooded region, on the other hand, no detectable rate (<0.001 μg N cm⁻³ h⁻¹) was observed. This indicates that the rates in the exposed region were mainly influenced by nitrate concentration in the interstitial waters accumulated by desiccation of sediments, whereas rates in the flooded region were strongly limited by no accumulation of nitrate in the anaerobic conditions. The potential denitrification rate, under the application condition of nitrate, ranged from 0.13 to 0.26 μg N cm⁻³ h⁻¹ in the flooded region and from 0.77 to 1.5 μg N cm⁻³ h⁻¹ in the exposed region. The potential rates in the flooded region had a tendency to be lower than those in the exposed region, implying that the number of denitrifying bacteria in the flooded region was low due to inactivation of aerobic respiration and denitrification in the denitrifying bacteria community. Kinetic parameters, maximum rate (V _max) and half-saturation constant (K _s) for denitrification were calculated on the experimental procedures of the wetting–drying cycles of sediments. Both parameters decreased by the wetting treatment and increased by the drying treatment. The fluctuation of V _max values with wetting–drying cycles indicated that the number of denitrifying bacteria was influenced by aerobic respiration and denitrification in the denitrifying bacteria community similar to the potential rates, and denitrifying enzyme was induced by the nitrate supplied by nitrification accelerated through the drying process. On the other hand, the fluctuation of K _s values implied that members of denitrifying bacteria were shifted to members of high nitrate affinity by wetting treatment and of low nitrate affinity by drying treatment.     

Effects of <Emphasis Type="Italic">Lactobacillus buchneri</Emphasis> and <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> on fermentation,aerobic stability,bacteria diversity and ruminal degradability of alfalfa silage

Silages are important feedstuffs. Homofermentative lactic acid bacterial inoculants are often used to control silage fermentation. However, some research pointed out those homofermentative lactic acid bacteria (LAB) impaired the aerobic stability of wheat, sorghum, and corn silages. Adding heterofermentative LAB can produce more acetic acid, thereby stabilizing silages during aerobic exposure. Alfalfa is difficult to ensile. The present work was to study the effects of L. buchneri (heterofermentative LAB), alone or in combination with L. plantarum (homofermentative LAB) on the fermentation, aerobic stability, bacteria diversity and ruminal degradability of alfalfa silage. After 90 days ensiling, the pH, NH₃-N/TN, butyric acid content and molds counts of control were the highest. The inoculated silages had more lactic acid, acetic acid content and more lactic acid bacteria than the control. Inoculating LAB inhibited harmful microorganisms, such as Enterobacterium and Klebsiella pneumoniae. The L. buchneri + L. plantarum-inoculated silage had more acetic acid and less yeasts than other three treatments (P < 0.05), and lower NH₃-N/TN than control (P < 0.05). The CO₂ production of L. buchneri + L. plantarum-inoculated silage was less than that of L. plantarum-inoculated silage (P < 0.05). Inoculating LAB in alfalfa silages can decrease pH, increase the production of lactic and acetic acids, reduce the number of yeasts and molds, and inhibit Enterobacterium and K. pneumoniae. Inoculating with L. buchneri or L. buchneri + L. plantarum can improve aerobic stability of alfalfa silages. A combination of L. buchneri and L. plantarum is preferable because it enhanced alfalfa silage quality and aerobic stability.     

The Effect of Gentian Violet on Virulent Properties of <Emphasis Type="Italic">Candida albicans</Emphasis>

The aim of this study was to evaluate the effect of gentian violet (GV) on phospholipase activity, proteinase activity and germ tube formation rate of Candida albicans. Both 12 phospholipase-positive and 12 proteinase-positive C. albicans isolates with Pz values ≤0.89 were obtained. A yeast suspension (1–3 × 10⁷ cfu/ml) of each isolate was prepared. After a brief exposure (60 min) to sub-therapeutic concentrations (0.5 or 2 μg/ml) of GV, Pz value of phospholipase, Pz value of proteinase and germ tube formation rate were determined. Phospholipase activity, proteinase activity and germ tube formation rate in two groups exposed to GV were significantly lower than those in the group unexposed (P < 0.05). The results of this study indicated that sub-therapeutic concentrations of GV may lead to reduction in phospholipase activity, proteinase activity and germ tube formation, and then may suppress virulence and pathogenicity of C. albicans.