Control of blue mold (Penicillium expansum) by fludioxonil in apples (cv Empire) under controlled atmosphere and cold storage conditions

A reduced risk fungicide, fludioxonil, was tested for its efficacy against blue mold caused by thiabendazole-resistant and -sensitive Penicillium expansum (Link) Thom in apples under three storage conditions. In a co-treatment, fludioxonil and inoculum were applied together to test the protective activity of the fungicide on wounds that had been aged for 1 or 2 days. The fungicide was also tested for its curative activity in post-inoculation treatment on apples that had been inoculated for 1 or 2 days. Fludioxonil was very effective as co-treatment and as post-inoculation treatment. At a concentration of 300 mg litre(-1), fludioxonil gave complete control of post-harvest blue mold caused by the thiabendazole-resistant and -sensitive P expansum for 105 days in controlled atmosphere (CA) storage at 2 (+/-1) degrees C, for 42 days in common cold storage at 4 (+/-1) degrees C and also in a shelf-life study for 6 days at 20 (+/-1) degrees C. Comparison on the effect of fludioxonil in CA storage and common cold storage showed that higher concentrations of fungicide were needed in cold storage than in CA storage. Fludioxonil at a concentration of 450 mg litre(-1), gave 98 and 92% control of blue mold of apples in the simulated shelf-life studies after CA and common cold storages, respectively. Fludioxonil has a potential to be incorporated in the fungicide resistance management strategies for control of blue mold in apples stored for 105 days.     

Improved Control of Postharvest Decay of Pears by the Combination of Candida sake (CPA-1) and Ammonium Molybdate

ABSTRACT The potential enhancement of Candida sake (CPA-1) by ammonium molybdate to control blue and gray mold caused by Penicillium expansum and Botrytis cinerea, respectively, on Blanquilla pears was investigated. In laboratory trials, improved control of blue and gray molds was obtained with the application of ammonium molybdate (1, 5, 10, and 15 mM) alone or in combination with C. sake at 2 x 10(6) or 2 x 10(7) CFU ml(-1) on Blanquilla pears stored at 20 degrees C. In semicommercial trials at 1 degrees C for 5 months, the efficacy of C. sake at 2 x 10(6) CFU ml(-1) on reducing P. expansum and B. cinerea decay was enhanced more than 88% with the addition of ammonium molybdate 5 mM in the 1999-2000 season. In two seasons, the performance C. sake at 2 x 10(6) CFU ml(-1) plus ammonium molybdate was similar to or greater than that of C. sake at 2 x 10(7) CFU ml(-1). Similar control of blue mold was obtained on pears stored under low oxygen conditions. The preharvest application of ammonium molybdate did not reduce postharvest blue mold decay. The population of C. sake on pear wounds significantly decreased in the presence of ammonium molybdate 1 and 5 mM at 20 and 1 degrees C.     

Liquid Formulation of the Postharvest Biocontrol Agent Candida sake CPA-1 in Isotonic Solutions

ABSTRACT Viability of the postharvest biocontrol agent Candida sake CPA-1 stored as liquid formulation was evaluated by studying the effect of growth, preservation medium, and temperature. C. sake was grown in molasses medium with unmodified water activity (a(w)) and in the same with a(w) modified to 0.98 with the addition of several solutes. Cells were preserved with isotonic solutions of different substances. Efficacy of liquid formulations stored for different periods was tested against infection by Penicillium expansum on apples. The best growth media were the (unmodified one and those modified to 0.98 a(w) with the addition of glycerol or sorbitol. For all growth media, the best preservation medium was the isotonic solution prepared with trehalose. When the effect of trehalose concentration in the preservation medium was studied, generally, at trehalose concentrations below the isotonic one, C. sake viabilities increased with increased trehalose. However, the best results were obtained when cells were preserved with the trehalose solution which was isotonic with cells. After 7 months of storage at 4 degrees C, cells that were grown in the sorbitol-modified medium and preserved with the isotonic solution of trehalose (0.96 M) maintained their viability and efficacy against P. expansum infection of apples.     

Improving Control of Green and Blue Molds of Oranges by Combining Pantoea Agglomerans (CPA-2) and Sodium Bicarbonate

The potential of using Pantoea agglomerans (strain CPA-2) alone, or in combination with sodium bicarbonate or sodium carbonate solutions, for control of Penicillium digitatum (green mold) and Penicillium italicum (blue mold) on oranges was investigated under ambient (20 °C) and cold storage (3 °C) conditions. P. agglomerans controlled both pathogens on oranges at 2 × 10⁸ cfu ml^-1. The biocontrol agent was found to be completely tolerant to 2% sodium bicarbonate at room temperature, although its culturability was reduced by > 1000-fold after 30 min in 2% sodium carbonate. The efficacy of P. agglomerans for control of green mold was improved when combined with sodium bicarbonate, resulting in complete and 97.6% reduction of decay incidence at 3 °C and 20 °C, when compared to untreated controls. Satisfactory results were also obtained with the combined treatment for control of blue mold. P. agglomerans grew well inside wounds on oranges at both 20 °C and 3 °C. In contrast, it showed a reduced growth on the surface of intact fruit. Sodium bicarbonate at 2% concentration did not noticeably affect antagonist population development. Thus, use of bicarbonate treatment at 2% followed by the antagonist P. agglomerans CPA-2 could be an alternative to chemicals for control of postharvest diseases on oranges.     

枯草芽孢杆菌(Bacillus subtilis) B-912对采后柑桔果实青、绿霉病的抑制效果

 用从土壤中分离到的枯草芽孢杆菌B-912作为生防拮抗菌,主要研究在不同贮藏温度下不同接种时间的B-912活菌液、热处理液和过滤液对柑桔青、绿霉病的抑制效果。B-912活菌液的抑菌效果最佳,热处理液和过滤液次之,但均显著地好于对照。较高的贮藏温度有利于拮抗菌对病菌的抑制作用,活菌液处理的果实在25℃下的发病率及病斑直径均小于15℃下的果实,24h后接种病菌孢子的果实其发病率及病斑直径一般都高于48h后接种的果实。实验证明,枯草芽孢杆菌的抑菌机理主要是产生抗菌素。     

Nutritional Enhancement of Biocontrol Activity of Candida sake (CPA-1) against Penicillium expansum on Apples and Pears

Pome fruits are poor in nitrogenous compounds and the addition of nitrogen can improve colonisation of the fruits by antagonists. Twenty-two nitrogenous compounds were evaluated for their effect on Candida sake (CPA-1) growth in vitro. Ten compounds that induced greater growth were applied with the antagonist to wounded fruits to evaluate their effect on enhancing control of Penicillium expansum. Calcium chloride and 2-deoxy-D-glucose were also tested. L-serine and L-aspartic acid enhanced biocontrol by C. sake against P. expansum on apples. On apples and pears, ammonium molybdate, calcium chloride and 2-deoxy-D-glucose improved the capacity of the antagonist to control P. expansum. The addition of ammonium molybdate at 1 mM allowed C. sake to be used on apples and pears at a lower concentration without diminishing control. Similar results were observed with the addition of calcium chloride to the antagonist. 2-deoxy-D-glucose at 6 and 18 mM enhanced biocontrol on pears by over 81%, but on apples the improvement of biocontrol was observed only at 6 mM. In cold storage, the combination of ammonium molybdate and C. sake completely eliminated the incidence of blue mould on pears, and reduced its severity and incidence by more than 80% on apples.     

木霉菌REMI转化体对番茄灰霉病的防治及其机理的研究

研究不同木霉菌转化体对番茄灰霉病防治效果及机理,为木霉菌生物防治的合理利用奠定基础。利用限制性内切酶介导基因整合技术(restriction enzyme-mediated integration,REMI),通过插入线性化质粒DNA获得了生物防治番茄灰霉病(Botrytis cinerea)效果优于出发菌T21菌株(出发菌)的3个木霉菌转化体Ttrm31、Ttrm34和Ttrm55,对侵染花器和叶片的灰霉病防效分别比原生物防治木霉菌株提高了16.9%和8%。木霉菌转化体的产孢能力、分生孢子的萌发率、对碳氮源的利用能力及对高温的抵抗能力都有所提高;木霉菌转化体本身产生的几丁质酶和β-1,3-葡聚糖酶的活性均比出发菌高,因此通过REMI技术可以获得新的有益木霉菌转化体,在一定程度上提高了生物菌株防治番茄灰霉病的水平。说明REMI技术可以用于改良生防木霉菌株的功能,提高生物防治效果。     

Effects of Ca2+ and Mg2+ on Botrytis cinerea and Penicillium expansum in vitro and on the biocontrol activity of Candida oleophila

Calcium salts have been reported to play an important role in the inhibition of postharvest decay of apples and in enhancing the efficacy of postharvest biocontrol agents. Therefore, the present study was conducted in order to examine and compare the effects of calcium and magnesium salts on the germination and metabolism of the postharvest pathogens Botrytis cinerea and Penicillium expansum , and to determine the effects of these salts on the biocontrol activity of two isolates (182 and 247) of the yeast Candida oleophila. Increasing concentrations of CaCl₂ (25–175 mM) resulted in decreased spore germination and germ-tube growth of both pathogens. The greatest effect was observed in the case of B. cinerea. The inhibitory effect could be overcome by the addition of glucose to the germination medium. MgCl₂ (25–175 mM) had no effect on germination or germ-tube growth of either pathogen, indicating that the calcium cation rather than the chloride anion was responsible for the inhibition. The pectinolytic activity of crude enzyme obtained from the culture medium of both pathogens was also inhibited by 25–175 mM CaCl₂, with the greatest effect on the crude enzyme from P. expansum. Biocontrol activity of isolate 182 was enhanced by the addition of 90 or 180 MM CaCl₂, whereas there was no effect on the biocontrol activity of isolate 247. This was apparently due to the inability of isolate 247 to proliferate in apple wounds. It is postulated that enhanced biocontrol activity of isolate 182 of the yeast C. oleophila in the presence of Ca²⁺ ions is directly due to the inhibitory effects of calcium ions on pathogen spore germination and metabolism, and indirectly due to the ability of isolate 182 to maintain normal metabolism in the presence of"toxic" levels of calcium.     

海洋放线菌A3202的分离鉴定及其对柑橘采后病害的防效

为获得用于防治柑橘采后病害的海洋放线菌,以柑橘青霉病菌Penicillium italicum、柑橘绿霉病菌P.digitatum和柑橘炭疽病菌Colletotrichum gloeosporioides为指示菌,对分离到的25株海洋放线菌进行筛选。通过平板对峙法测定拮抗菌株的抑菌谱,并测定其发酵产物粗提物对柑橘果实采后病害的防效,根据形态特征、培养特征、生理生化特征及16S rDNA序列对其进行鉴定。结果表明,分离自鳞笠藤壶Tetraclita squamosa的菌株A3202对3种指示菌均具有强抑菌活性,对供试13种植物病原菌的菌丝生长具有不同程度的抑制作用,尤其对柑橘青霉病菌和柑橘绿霉病菌的抑制作用最强,抑菌带宽度分别可达2.33±0.05 cm和2.32±0.10 cm。该菌株800 mg/L粗提物溶液对接种后7 d的柑橘青霉病、柑橘绿霉病和柑橘炭疽病的相对防效均可达100%。初步鉴定该菌株为放线菌中的米修链霉菌Streptomyces misionensis。     

柑橘内生燕麦镰刀菌Gds-1对柑橘青霉病的防治研究

柑橘青霉病是柑橘果实采后危害最大的病害。为得到一株可有效应用于柑橘青霉病防治的柑橘内生真菌菌株,进行了柑橘果实内生菌分离、离体与活体试验筛选、菌株形态学与多基因位点分子系统发育鉴定、菌株活体应用效果与作用特点以及菌株代谢产物稳定性与应用防效试验。结果表明:筛选所得的柑橘内生真菌Gds-1在离体与活体条件下均对柑橘青霉菌有较好的抑制效果;经多基因位点联合系统发育分析,将Gds-1鉴定为燕麦镰刀菌Fusarium avenaceum;提前48 h施用Gds-1菌体,对柑橘青霉病的预防效果最好 (防治效果为90.67%);Gds-1菌丝不会损害健康柑橘果实表皮,但可以在柑橘果实表皮伤口和被柑橘青霉菌感染的组织部位发挥作用,从而抑制柑橘青霉菌;当温度在 ?80~100 ℃和pH=5~10时,Gds-1无菌发酵液对柑橘青霉菌的拮抗作用高效稳定;单独施用Gds-1无菌发酵滤液28 d和56 d时,对柑橘青霉病的防效与100 μg/mL的抑霉唑相当,显著高于清水对照。本研究首次报道了生防镰刀菌F. avenaceum Gds-1对柑橘青霉病的防治作用,为柑橘果实采后生物源防腐剂的选择提供了新来源,为镰刀菌生物防治机理研究提供了新思路。     

Characterization of fludioxonil-resistant and pyrimethanil-resistant phenotypes of Penicillium expansum from apple

Penicillium expansum is the primary cause of blue mold, a major postharvest disease of apple. Fludioxonil and pyrimethanil are two newly registered postharvest fungicides for pome fruit in the United States. To evaluate the potential risk of resistance development in P. expansum to the new postharvest fungicides, one isolate of each of thiabendazole-resistant (TBZ-R) and -sensitive (TBZ-S) P. expansum was exposed to UV radiation to generate fungicide-resistant mutants. Four fludioxonil highly-resistant mutants (EC(50) > 1,000 microg/ml) and four pyrimethanil-resistant mutants (EC(50) > 10 microg/ml) were tested for sensitivities to thiabendazole, fludioxonil, and pyrimethanil, and fitness parameters including mycelial growth, sporulation on potato dextrose agar (PDA), sensitivity to osmotic stress, and pathogenicity and sporulation on apple fruit. The stability of resistance of the mutants was tested on PDA and apple fruit. Efficacy of the three fungicides to control blue mold incited by the mutants was evaluated on apple fruit. Six fungicide-resistant phenotypes were identified among the parental wild-type isolates and their mutants based upon their resistance levels. All four fludioxonil highly-resistant mutants were sensitive to pyrimethanil and retained the same phenotypes of resistance to TBZ as the parental isolates. All four pyrimethanil-resistant mutants had a low level of resistance to fludioxonil with a resistance factor >15. The two pyrimethanil-resistant mutants derived from a TBZ-S isolate became resistant to TBZ at 5 microg/ml. After 20 successive generations on PDA and four generations on apple fruit, the mutants retained the same phenotypes as the original generations. All mutants were pathogenic on apple fruit at both 0 and 20 degrees C, but fludioxonil highly-resistant mutants were less virulent and produced fewer conidia on apple fruit than pyrimethanil-resistant mutants and their parental wild-type isolates. Compared with the parental isolates, all four fludioxonil highly-resistant mutants had an increased sensitivity to osmotic stress on PDA amended with NaCl, while the pyrimethanil-resistant mutants did not. Pyrimethanil was effective against blue mold caused by fludioxonil-resistant mutants at both 0 and 20 degrees C. Pyrimethanil and fludioxonil reduced blue mold incited by pyrimethanil-resistant mutants during 12-week storage at 0 degrees C but were not effective at 20 degrees C. TBZ was not effective against pyrimethanil-resistant mutants derived from TBZ-S wild-type isolates at room temperature but provided some control at 0 degrees C. The results indicate that: (i) a fitness cost was associated with fludioxonil highly resistant mutants of P. expansum in both saprophytic and pathogenic phases of the pathogen but not pyrimethanil-resistant mutants; (ii) pyrimethanil possessed a higher risk than fludioxonil in the development of resistance in P. expansum; and (iii) triple resistance to the three apple-postharvest fungicides could emerge and become a practical problem if resistance to pyrimethanil develops in P. expansum populations.     

Control of Blue Mold of Apples by Preharvest Application of Candida sake Grown in Media with Different Water Activity

ABSTRACT Unmodified and low water activity (a(w))-tolerant cells of Candida sake CPA-1 applied before harvest were compared for ability to control blue mold of apples ('Golden Delicious') caused by Penicillium expansum under commercial storage conditions. The population dynamics of strain CPA-1 on apples were studied in the orchard and during storage following application of 3 x 10(6) CFU/ml of each treatment 2 days prior to harvest. In the field, the population size of the unmodified treatment remained relatively unchanged, while the population size of the low-a(w)-modified CPA-1 cells increased. During cold storage, the populations in both treatments increased from 10(3) to 10(5) CFU/g of apple after 30 days, and then declined to about 2.5 x 10(4) CFU/g of apple. In laboratory studies, the low-a(w)-tolerant cells provided significantly better disease control as compared with the unmodified cells and reduced the number of infected wounds and lesion size by 75 and 90%, respectively, as compared with the non-treated controls. After 4 months in cold storage, both unmodified and low-a(w)-tolerant cells of C. sake were equally effective against P. expansum on apple (>50% reduction in size of infected wounds).     

Effect of Metschnikowia pulcherrima and methyl jasmonate on apple blue mold disease and the possible mechanisms involved

Phytoparasitica - Metschnikowia pulcherrima alone and in combination with methyl jasmonate [MeJA] was applied for control of blue mold of apple caused by Penicillium expansum. In vitro, MeJA at...     

生防木霉菌耐三唑类杀菌剂菌株的选育

应用含药培养基诱导和紫外线诱变相结合的方法,对优良生防木霉菌株T2-16进行了抗三唑类杀菌剂的遗传改良,获得了具有较好耐药性突变体13株。通过测定突变株对水稻纹枯病菌（Rhizoctonia solani）、稻瘟病菌（Magnaporthe oryzae）和稻曲病菌（Ustilaginoidea virens）的拮抗性,获得1株拮抗活性高、对三唑类杀菌剂耐性好的突变体TUV-13,其对腈菌唑抗性提高10倍,对三唑酮抗性提高51倍,且耐药性可以稳定遗传。     

Characterization of an Exo-beta-1,3-Glucanase Produced by Pichia anomala Strain K, Antagonist of Botrytis cinerea on Apples

ABSTRACT The exo-beta-1,3-glucanase (EC 3.2.1.58) activity of Pichia anomala strain K, an antagonistic yeast of Botrytis cinerea on postharvest apples, was studied in a synthetic medium supplemented with laminarin, a cell wall preparation (CWP) of B. cinerea, or glucose. The highest enzyme activity was detected in culture media containing a CWP of B. cinerea as the sole carbon source, whereas the lowest activity was observed in culture media supplemented with glucose. Exoglc1, an exo-beta-1,3-glucanase, was purified to homogeneity from culture filtrates of strain K containing a CWP. The molecular mass of exoglc1 was estimated to be under 15 kDa. Optimum activity of exoglc1 was recorded at 50 degrees C and pH 5.5. The exoglc1 K(m) value was estimated at 22.4 mg/ml. Exoglc1 showed in vitro a stronger inhibitory effect on germ tube growth of B. cinerea than on conidia germination and caused morphological changes such as leakage of cytoplasm and cell swelling. Exo-beta-1,3-glucanase activity was detected on apples treated with strain K and was similar to exoglc1 on the basis of activity on native gel. Moreover, the addition of a CWP to a suspension of P. anomala stimulated both in situ exo-beta-1,3-glucanase activity and protective activity against the pathogen, strengthening the hypothesis that exo-beta-1,3-glucanase activity is one of the mechanisms of action involved in the suppression of B. cinerea by P. anomala strain K.     

梨灰霉病菌拮抗细菌Pseudomonas extremorientalis的鉴定、发酵条件优化及防效评价

灰霉病是梨贮藏期的主要病害,发病率高,为害严重。为了有效控制该病害发生,利用平皿稀释法从梨根际土壤中分离内生细菌,并采用琼脂平板扩散法进行抑菌活性初筛,筛选出1株拮抗细菌L21,基于形态特征、生理生化特性及16S rRNA和gyrB序列分析,鉴定为Pseudomonas extremorientalis。采用生长速率法测定菌株L21的无菌发酵液对12种病原真菌均有抑制作用,采用Salkowski比色法测定菌株L21能够分泌吲哚-3-乙酸（IAA）,采用酪蛋白培养基平板检测菌株L21可以产生胞外蛋白酶。在单因素试验的基础上,通过Plackett-Burman试验设计筛选出pH、硫酸锰和转速3个影响发酵的重要因素,利用最陡爬坡试验和Box-Behnken试验设计,获得菌株L21的最佳发酵条件为蔗糖20 g/L、牛肉膏20 g/L、硫酸锰3.00 g/L、甘油1 g/L、K₂HPO₄ 1.50 g/L、接种量8%、温度34℃、pH 7.31、转速200.66 r/min和培养时间15 h。处理96 h后,菌株L21对梨灰霉病的防效为74.23%,与多菌灵的防效差异不显著。本研究表明菌株L21具有广谱抑菌活性,为植物真菌病害的生物防治提供新的生防资源。     

Fenpropimorph: a promising fungicide for postharvest diseases in citrus fruits

Sour rot, green mold and blue mold are postharvest diseases of citrus fruit. Benzimidazole and imidazole fungicides control molds, and guazatine controls sour rot, but strains ofPenicillium spp. resistant to these chemicals have been reported. Aqueous formulations of fenpropimorph, a morpholine fungicide, are very active in controlling fungi attacking postharvest citrus fruits. The fungicidal effect of the chemical in the coating wax was investigated in combined treatments with guazatine in dip or spray applications on various citrus fruit varieties. Fenpropimorph alone was as good as or a better curative and protective treatment than the current commercial treatments applied in packinghouses in Israel for decay control.     

哈茨木霉T2-16的GFP标记及其生防特性

优化高效拮抗生防菌哈茨木霉T2-16的转化条件,筛选出与野生型菌株具有相似生防特性的阳性转化子,为生防木霉菌T2-16的定殖动态、分布规律等研究打下基础。通过PCR和分子克隆技术构建具有G418抗性基因的绿色荧光（GFP）表达载体pKN-sGFP,利用PEG-CaCl₂介导的原生质体转化法,获得强荧光表达的哈茨木霉T2-16转化子,并将其与野生型菌株的生物特性进行比较,筛选出与野生型菌株具有相似生防特性的阳性转化子。试验结果显示,哈茨木霉T2-16在20℃培养条件下对1000 μg/mL G418敏感,在上述优化条件下,转化获得稳定遗传的阳性转化子TG2-10;进一步比较其与野生型菌株的生物特性发现,两者之间无明显差异,可用于下一步哈茨木霉T2-16生防机理的研究。     

葡萄霜霉病生防菌甲基营养型芽胞杆菌T3的鉴定及其防治效果

为了获得对葡萄霜霉病具有拮抗效果的生防菌株,本研究通过平板稀释法从葡萄园土壤中分离细菌,采用离体叶片混合点样法筛选拮抗菌,并进行了田间防效试验。根据菌株的形态学及16S rDNA序列分析对其进行鉴定,并检测了菌株T3的代谢产物。在分离获得的31株细菌中,菌株T1-2和T3发酵液对葡萄霜霉病菌的室内抑制率与对照枯草芽胞杆菌CN181一致,均为100%;2次田间试验均表明,在7 d时,清水对照的病情指数增加值平均为44.3,菌株T3发酵液的病病情指数增加值平均为21.0,对葡萄霜霉病的相对防治效果为52.4%,与菌株CN181发酵液无显著差异。经鉴定,菌株T3为甲基营养型芽胞杆菌Bacillus methylotrophicus,且该菌株在代谢过程中可产生蛋白酶、纤维素酶和嗜铁素等抑菌物质。研究结果表明,菌株T3对葡萄霜霉病菌具有强烈的抑制作用,并对葡萄霜霉病具有较好的防治效果。     

The effects of some factors on the growth and morphology of Naegleria sp. and three strains of the genus Acanthamoeba.

The effects of various biophysical and chemical factors on the cytology of vegetative stages of Naegleria sp., Vitek strain, Acanthamoeba culbertsoni, Acanthamoeba castellanii, Neff strain and Acanthamoeba polyphaga, No. 1289, were studied. The amoebae were cultured in a liquid medium under axenic conditions. The optimum temperature was 37 degrees C for pathogenic strains of Naegleria sp. and Acanthamoeba culbertsoni and 20 degrees C for A. castellanii. No changes were observed in the growth of A. polyphaga at the temperatures 20 degrees and 37 degrees C. The strains investigated grew at pH values of 5.6 to 7.7 using Soerensen's buffer. At the limit values the growth was inhibited and the morphology of cells was markedly changed. All of the four strains grew still at pH 8.4 kept by NaHCO3. A. polyphaga grew at partial anaerobiosis. The three tested strains of the genus Acanthamoeba grew in liquid axenic medium with 0.89% NaCl. The growth of Naegleria sp., Vitek was inhibited already at 0.2% concentration of this salt. The addition of 3 X 10(-2) m KCl to the culture medium had a harmful effect on the growth and morphology of three tested strains, except A. polyphaga. In the culture medium containing 2 X 10(-3) m CaCl2 the encystment of both pathogenic strains was stimulated. The cytological changes under experimental conditions were manifested by atypical movement of trophozoits and their intracellular structure.