Viability of the nematophagous fungus Pochonia chlamydosporia after passage through the gastrointestinal tract of horses

Abstract

The predatory capacity of the nematophagous fungus Pochonia chlamydosporia (isolate VC4) embedded in sodium alginate pellets after passage through the gastrointestinal tract of horses was assessed in vitro against Oxyuris equi eggs. Twelve previously dewormed crossbred mares, average weight of 362.5kg (+/-21) were used in the experiment. Each animal of the treated group received an oral dose (100g) of sodium alginate pellets containing P. chlamydosporia mycelial mass. The control group received pellets without fungus. Faecal samples from fungus-treated and control groups were collected at intervals of 8, 12, 24, 36, 48 and 72h after pellet administration and placed in Petri dishes containing 2% water-agar. One thousand eggs of O. equi were plated in Petri dishes of both treated and control groups, with six replicates, and incubated in oven, 25 degrees C, in the dark, for 30 days. At the end of the experiment, one hundred eggs were removed from each Petri dish and classified according to the following parameters: type 1, physiological and biochemical effect without morphological damage to eggshell, with hyphae adhered to the shell; type 2, lytic effect with morphological change in the eggshell and embryo without hyphal penetration, and type 3, lytic effect with morphological change in the eggshell and embryo, with hyphal penetration and internal egg colonization. Chlamydospore production was observed in Petri dishes of the treated group. The isolate VC4 remained viable after passing through the gastrointestinal tract of horses and maintained the ovicidal activity against O. equi eggs when compared with the control group (p<0.01) after each collection interval: 29.1% (8h), 28.2% (12h), 31.1% (24h), 27.4% (36h), 30.9% (48h) and 28.4% (72h). The results suggest that P. chlamydosporia could be used as an effective biological control agent of O. equi eggs in natural conditions.

Ação ovicida do extrato bruto enzimático do fungo Pochonia chlamydosporia sobre ovos de Ancylostoma sp

“…De acordo com Esteves e cols 7 , alguns trabalhos têm demonstrado que isolados fúngicos de Pochonia chlamydosporia são capazes de produzir extratos enzimáticos contra vários tipos de substratos sólidos, e dentre esses, os polissacarídeos, as proteínas e os lipídios. Além disso, sua ação ovicida tem sido testada com sucesso contra ovos de vários gêneros de geo-helmintos em condições laboratoriais e a campo 5,8 . Contudo, seu extrato bruto enzimático nunca foi testado sobre ovos de geo-helmintos, e dentre esses de Ancylostoma sp, constituindo dessa forma, uma alternativa de controle.…”

“…Ainda de acordo com Mukhtar e Pervaz 10 a ação nematicida do filtrado de Pochonia chlamydosporia sobre juvenis de Meloidogyne javanica pode ser atribuída com a produção de certas enzimas e toxinas do tipo verticillim A, B e C que ajudam a enfraquecer e dissolver a cutícula dos nematoides. Recentemente, Braga e cols 8 demonstraram a viabilidade desse fungo após passagem pelo trato gastrintestinal de equinos e comprovaram sua capacidade ovicida sobre ovos de Oxyuris equi, nematoide gastrintestinal de equinos, ao final do ensaio. Contudo, existe uma carência de trabalhos que possam evidenciar a ação de Pochonia chlamydosporia sobre larvas infectantes de nematoides gastrintestinais de animais domésticos e, mais pesquisas são necessárias.…”

Biological control of Fasciola hepatica eggs with the Pochonia chlamydosporia fungus after passing through the cattle gastrointestinal tract

“…Moreover, according to Terrill et al (2004), chlamydospore production by fungi is essential to its spread after stressful conditions. Braga et al (2010) reported that this fungus was effective in going through horses' gastrointestinal tract, keeping its ovicidal activity. Comparing our work with the records of the above work, it is noted that the results were similar, allowing us to evaluate some points: "(1) in the two studies, P. chlamydosporia structures (chlamydospores) were observed present in stool samples on Petri dishes for the treated group animals; (2) both results mentioned the ovicidal activity from the interval of 12 h; (3) pellets were recovered in stool samples of the treated group animals until the last studied interval."…”

“…After that, 2 g of feces from each sample was removed, homogenized, and placed in a Petri dish 9 cm in diameter, containing 2% water-agar. One thousand F. hepatica eggs were poured on Petri dishes of the treated and control groups and were incubated at 26°C for a period of 35 days, according to the described methodology by Braga et al (2010). Six replications were performed in the treated and control groups for each studied period.…”

“…Biological control with ovicidal nematophagous fungi especially the Pochonia chlamydosporia fungus has shown promising results in the control of eggs of various helminth (Stirling 1991;Dias et al 2007;De et al 2008;Braga et al 2010). P. chlamydosporia destroys helminth eggs through structures known as appressoria (Kerry and Hidalgo 2004).…”