RESUMO

Edaphic factors can modulate the effects of microbial inoculants on crop yield promotion. Given the potential complexity of microbial inoculant responses to diverse soil management practices, we hypothesize that sustainable management of soil and water irrigation may improve soil quality and enhance the effects of plant growth-promoting bacteria (PGPB). Consequently, the primary objective was to assess the effectiveness of microbial inoculants formulated with Herbaspirillum seropedicae (Hs) and Azospirillum brasilense (Ab) on maize growth in soils impacted by different historical conservation management systems. We evaluated two soil management systems, two irrigation conditions, and four treatments: T0 - without bioinoculant and 100% doses of NPK fertilization; T1 - Hs + humic substances and 40% of NPK fertilization; T2 - Ab and 40% of NPK fertilization; T3 - co-inoculation (Hs + Ab) and 40% of NPK fertilization. Using a reduced fertilization dose (40% NPK) associated with microbial inoculants proved efficient in increasing maize shoot dry mass : on average, there was a 16% reduction compared to the treatment with 100% fertilization. In co-inoculation (Hs + Ab), the microbial inoculants showed a mutualistic effect on plant response, higher than isolate ones, especially increasing the nitrogen content in no-tillage systems irrigated by swine wastewater. Under lower nutrient availability and higher biological soil quality, the microbial bioinputs positively influenced root development, instantaneous water use efficiency, stomatal conductance, and nitrogen contents.

RESUMO

As agricultural practices become more sustainable, adopting more sustainable practices will become even more relevant. Searching for alternatives to chemical compounds has been the focus of numerous studies, and bacteriocins are tools with intrinsic biotechnological potential for controlling plant diseases. We continued to explore the biotechnological activity of the bacteriocin Gluconacin from Gluconacetobacter diazotrophicus, PAL5 strain, by investigating this protein's antagonism against important tomato phytopathogens and demonstrating its effectiveness in reducing bacterial spots caused by Xanthomonas perforans. In addition to this pathogen, the bacteriocin Gluconacin demonstrated bactericidal activity in vitro against Ralstonia solanacearum and Pseudomonas syringae pv. tomato, agents that cause bacterial wilt and bacterial spots, respectively. Bacterial spot control tests showed that Gluconacin reduced disease severity by more than 66%, highlighting the biotechnological value of this peptide in ecologically correct formulations.

RESUMO

This work aimed to evaluate the in vitro anthelmintic effect of carvone nanoemulsions on Haemonchus contortus. Three R-carvone nanoemulsions were prepared: uncoated R-carvone nanoemulsions homogenized in a sonicator (UNAlg-son) and homogenized in an ultrahomogenizer (UNAlg-ultra) and sodium alginate-coated R-carvone (CNAlg-ultra). The physicochemical characterizations of the nanoemulsions were carried out. The anthelmintic activity was evaluated using egg hatch test (EHT), larval development test (LDT) and adult worm motility test (AWMT). Changes in cuticle induced in adult H. contortus were evaluated by scanning electron microscopy (SEM). The results were subjected to analysis of variance and compared using the Tukey test (P < 0.05). The effective concentration to inhibit 50% (EC50) of egg hatching and larval development was calculated. The particle sizes were 281.1 nm (UNAlg-son), 152.7 nm (UNAlg-ultra) and 557.8 nm (CNAlg-ultra), and the zeta potentials were −15 mV (UNAlg-son), −10.8 mV (UNAlg-ultra) and −24.2 mV (CNAlg-ultra). The encapsulation efficiency was 99.84 ± 0.01%. SEM of the nanoemulsions showed an increase in size. In EHT, the EC50 values of UNAlg-son, UNAlg-ultra and CNAlg-ultra were 0.19, 0.02 and 0.17 mg mL−1, respectively. In LDT, they were 0.29, 0.31 and 0.95 mg mL−1 for UNAlg-son, UNAlg-ultra and CNAlg-ultra, respectively. The adult motility inhibition was 100% after 12 h of exposure to UNAlg-ultra and CNAlg-ultra, while for UNAlg-son, it was 79.16%. SEM showed changes in the buccal capsule and cuticular damage. It was concluded that R-carvone nanoemulsions showed antiparasitic action demonstrating promise for the control of infections caused by gastrointestinal nematodes in small ruminants.

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Medicinal plants have been the focus of several studies due to their nematicide properties which can be used to control nematodes in sheep. No study has examined the morphological effects of Cymbopogon citratus on nematodes. Thus, this study evaluated the chemical composition, nematicidal activity and effects of C. citratus extracts on the morphology of eggs and infective larvae (L3) of sheep. Aqueous and methanolic extracts and fractions of C. citratus were obtained and analysed in vitro. The C. citratus extracts were effective against Haemonchus spp. and Trichostrongylus spp. larvae and eggs. Ten fractions were obtained from C. citratus, six of which had high ovicidal activity at 1000 µg mL-1, and two fractions had high activity at all tested concentrations. The phytochemical analysis identified the presence of compounds such as terpenoids, various ketones, esters, and fatty acids. The ultrastructural analysis showed deformations of the cuticle and wilting along the body of the nematodes at all concentrations. The muscular layer, intestinal cells and the mitochondria profile showed damage compared to the typical pattern. Ultra-thin sections of eggs treated with methanolic fractions of C. citratus presented modifications. This study showed the biological activity and effects of C. citratus on the gastrointestinal nematodes in sheep.

Assuntos

RESUMO

This study aimed to evaluate the anthelmintic and ultrastructural effects of Calotropis procera latex on Haemonchus contortus. C. procera latex was twice centrifuged at 10,000×g and dialyzed to obtain a fraction rich in proteins, named LP (latex protein), and at 3,000 rpm to obtain a fraction rich in secondary metabolites, named LNP (latex non-protein). Specimens of H. contortus exposed to LNP, LP and PBS in the Adult Worm Motility Test (AWMT) were submitted to scanning (SEM) and transmission (TEM) electron microscopy to verify changes in their ultrastructure. Phytochemical tests in the LNP indicated the presence of phenols, steroids, alkaloids and cardenolides. High-Performance Liquid Chromatography (HPLC) characterized the presence of the compounds gallic acid and quercetin in the LNP. The protein content in the LP was 43.1 ± 1.1 mg/mL and 7.7 ± 0.3 mg/mL in LNP. In AWMT, LNP and LP inhibited the motility of 100% of the nematodes, with LNP being more effective than LP and ivermectin more effective than both (p <0.05). Cuticle changes were observed by SEM and TEM in nematodes treated with LP and LNP. Calotropis procera latex has anthelmintic effects against H. contortus, causing damage to its cuticle and other alterations in its ultrastructure.(AU)

Este estudo objetivou avaliar os efeitos anti-helmínticos e ultraestruturais do látex de Calotropis procera sobre Haemonchus contortus. Látex de C. procera foi centrifugado duas vezes à a 10.000xg e dialisado para obter uma fração rica em proteínas, denominada proteínas do látex (LP). E centrifugado e centrifugado a 3.000 rpm, para obter uma fração rica em metabólitos secundários, denominada LNP (látex não proteico). Espécimes de H. contortus expostos à LNP, LP e PBS no Teste de Motilidade dos Nematoides Adultos (TMNA) foram submetidos a microscopia eletrônica de varredura (MEV) e de transmissão (MET), para verificar alterações em sua ultraestrutura. Testes fitoquímicos em LNP indicaram a presença de fenóis, esteroides, alcaloides e cardenolídeos. A presença dos compostos ácido gálico e quercetina em LNP foi caracterizada por Cromatografia Líquida de Alta Eficiência (CLAE). O conteúdo de proteínas em LP foi de 43,1 ± 1,1 mg/mL e de 7,7 ± 0,3 mg/mL em LNP. No TMNA, LNP e LP inibiram a motilidade de 100% dos nematoides, sendo LNP mais eficaz que LP, e a ivermectina mais eficaz que ambos (p <0,05). Alterações na cutícula de nematoides tratados com LP e LNP foram observadas por MEV e MET. O látex de C. procera apresenta efeito anti-helmíntico sobre H. contortus, causando danos à sua cutícula e outras alterações em sua ultraestrutura.(AU)

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This study aimed to evaluate the anthelmintic activity of Eucalyptus citriodora essential oil and citronellal on sheep gastrointestinal nematodes. Essential oil composition was determined by gas chromatography mass spectrometry. The substances were evaluated in vitro using adult worm motility test (AWMT) and transmission electron microscopy (TEM). The acute toxicity test in mice and the fecal egg count reduction test (FECRT) in sheep were performed. Citronellal was confirmed as the essential oil major constituent (63.9%). According to the AWMT, 2 mg/mL of essential oil and citronellal completely inhibited Haemonchus contortus motility at 6 h post exposure. H. contortus exposed to essential oil and citronellal exhibited internal ultrastructural modifications. The lethal dose 50 values in mice were 5,000 and 2,609 mg/kg for essential oil and citronellal, respectively. E. citriodora essential oil reduced sheep epg at 14 days post treatment by 69.5% (P<0.05). No significant differences were observed in epg between the citronellal and negative control groups (P>0.05). The interaction between citronellal and other constituents in the essential oil may be relevant for its in vivo anthelmintic activity. Thus, E. citriodora essential oil and citronellal pharmacokinetic studies may help elucidate the anthelmintic activity of these compounds.

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The aim here is to present data on the efficacy of anthelmintics in sheep flocks in Rio de Janeiro, Brazil, and to discuss the interpretation of the fecal egg count reduction test (FECRT) for each nematode genus. Fecal eggs counts and pre- and post-treatment coprocultures were performed, the former to evaluate the efficacy of and the latter to determine the overall parasite prevalence. An additional efficacy test was performed at Farm # 1 a year after the initial test. Severe anthelmintic resistance was found for the flocks, with no FECRT sensitivity at any of the 22 farms evaluated. However, an analysis of the infective larvae showed that some drugs were effective against certain parasitic genera; i.e., levamisole was more effective against Haemonchus spp. and moxidectin against Trichostrongylus spp. In the additional FECRT performed at Farm # 1, moxidectin and nitroxynil were ineffective separately, but when applied in combination they were highly effective due to their efficacy against Haemonchus (nitroxynil) and Trichostrongylus (moxidectin), respectively. The use of the FECRT targeting the parasitic nematode species prevalent on farms may make it possible to choose more effective anthelmintics.

Assuntos

RESUMO

Abstract This study aimed to evaluate the anthelmintic activity of Eucalyptus citriodora essential oil and citronellal on sheep gastrointestinal nematodes. Essential oil composition was determined by gas chromatography mass spectrometry. The substances were evaluated in vitro using adult worm motility test (AWMT) and transmission electron microscopy (TEM). The acute toxicity test in mice and the fecal egg count reduction test (FECRT) in sheep were performed. Citronellal was confirmed as the essential oil major constituent (63.9%). According to the AWMT, 2 mg/mL of essential oil and citronellal completely inhibited Haemonchus contortus motility at 6 h post exposure. H. contortus exposed to essential oil and citronellal exhibited internal ultrastructural modifications. The lethal dose 50 values in mice were 5,000 and 2,609 mg/kg for essential oil and citronellal, respectively. E. citriodora essential oil reduced sheep epg at 14 days post treatment by 69.5% (P<0.05). No significant differences were observed in epg between the citronellal and negative control groups (P>0.05). The interaction between citronellal and other constituents in the essential oil may be relevant for its in vivo anthelmintic activity. Thus, E. citriodora essential oil and citronellal pharmacokinetic studies may help elucidate the anthelmintic activity of these compounds.

Resumo Este trabalho objetivou avaliar a atividade anti-helmíntica do óleo essencial de Eucalyptus citriodora e citronelal sobre nematoides gastrintestinais de ovinos. A composição do óleo essencial foi determinada por cromatografia gasosa acoplada à espectrometria de massas. As substâncias foram avaliadas in vitro utilizando-se teste de motilidade de vermes adultos (AWMT) e microscopia eletrônica de transmissão (TEM). Teste de toxicidade aguda em camundongos e teste de redução da contagem de ovos fecais (FECRT) em ovinos foram realizados. Citronelal foi confirmado como componente majoritário do óleo essencial (63,9%). No AWMT, 2 mg/mL de óleo essencial e citronelal inibiram completamente a motilidade de H. contortus 6 h pós-exposição. H. contortus expostos ao óleo essencial e citronelal exibiram modificações ultraestruturais internas. Os valores da dose letal 50 em camundongos foram 5.000 e 2.609 mg/kg para óleo essencial e citronelal, respectivamente. Óleo essencial de E. citriodora reduziu opg de ovinos 14 dias pós-tratamento em 69,5% (P<0,05). Não houve diferença significativa de opg entre grupo controle negativo e citronelal (P>0,05). A interação entre citronelal e outros constituintes do óleo essencial pode ser relevante na atividade anti-helmíntica in vivo. Portanto, avaliação farmacocinética do óleo essencial de E. citriodora e citronelal pode auxiliar a elucidar a atividade anti-helmíntica desses compostos.

Assuntos

RESUMO

Abstract The aim here is to present data on the efficacy of anthelmintics in sheep flocks in Rio de Janeiro, Brazil, and to discuss the interpretation of the fecal egg count reduction test (FECRT) for each nematode genus. Fecal eggs counts and pre- and post-treatment coprocultures were performed, the former to evaluate the efficacy of and the latter to determine the overall parasite prevalence. An additional efficacy test was performed at Farm # 1 a year after the initial test. Severe anthelmintic resistance was found for the flocks, with no FECRT sensitivity at any of the 22 farms evaluated. However, an analysis of the infective larvae showed that some drugs were effective against certain parasitic genera; i.e., levamisole was more effective against Haemonchus spp. and moxidectin against Trichostrongylus spp. In the additional FECRT performed at Farm # 1, moxidectin and nitroxynil were ineffective separately, but when applied in combination they were highly effective due to their efficacy against Haemonchus (nitroxynil) and Trichostrongylus (moxidectin), respectively. The use of the FECRT targeting the parasitic nematode species prevalent on farms may make it possible to choose more effective anthelmintics.

Resumo O objetivo deste trabalho foi apresentar dados sobre a eficácia de anti-helmínticos em rebanhos ovinos no Rio de Janeiro, Brasil, e discutir a interpretação do teste de redução da contagem de ovos nas fezes (TRCOF) para cada gênero de nematoide. A contagem de ovos fecais (OPG) e coprocultura pré e pós-tratamento foram realizadas para avaliar a eficácia e a prevalência geral do parasito, respectivamente. Um teste de eficácia adicional foi realizado na Fazenda # 1 após um ano do teste inicial. Resistência anti-helmíntica grave foi encontrada, não havendo sensibilidade no TRCOF em nenhuma das 22 fazendas avaliadas. No entanto, na análise das larvas infectantes observou-se que algumas drogas foram eficazes contra certos gêneros parasitários; por exemplo, o levamisol foi mais eficaz contra Haemonchus spp. e a moxidectina contra Trichostrongylus spp. No TRCOF adicional realizado na Fazenda 1, a moxidectina e o nitroxinil foram ineficazes separadamente, mas quando aplicados em combinação, foram altamente eficazes devido à sua eficácia contra Haemonchus spp. (nitroxinil) e Trichostrongylus spp. (moxidectina), respectivamente. O TRCOF visando às espécies de nematoides parasitas prevalentes nas fazendas pode possibilitar a escolha de anti-helmínticos mais eficazes.

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We describe the synthesis and a function of melanin in Duddingtonia flagrans, a nematode-trapping fungus. We tested various culture media treated with L-DOPA, glucose and tricyclazole on fungal growth and melanin distribution using infrared spectroscopy (IS), electron paramagnetic resonance (EPR) and transmission electron microscopy (TEM). In vitro rumen digestion was used to test the environmental stress and then to evaluate the capacity of this fungus to trap nematode larvae. The growth and melanization of the fungus after 21 days of incubation at 30°C were best in Sabouraud dextrose medium. IS indicated the presence of melanin in D. flagrans, with similar bands for commercial melanin used as a control, and assigned the values obtained by EPR (g of 2.0051 ± 0.0001) to the production of melanin by the fungus. TEM indicated that melanin was produced in melanosomes but was not totally inhibited by tricyclazole. Within the limits of experimental error, the predatory activity of fungus treated with tricyclazole was drastically affected after 27 h of in vitro anaerobic stress with rumen inoculum. The deposition of melanin particles on the fungal cell wall contributed to the maintenance of D. flagrans predatory abilities after in vitro anaerobic ruminal stress.