Enhancing chlamydospore production in Duddingtonia flagrans on solid substrate: The impact of mannitol and varied cultivation conditions.

Duddingtonia flagrans is a nematophagous fungus which has shown promising results as a non-chemical parasitic control tool. The fungus disrupts the parasite's life cycle by trapping larvae in the environment through the networks generated from chlamydospores, thus preventing the reinfection of animals. One barrier to the development of a commercial product using this tool is the need to increase chlamydospore production in the laboratory for its administration to livestock. The purpose of this study was to evaluate the addition of mannitol to an enriched culture medium and the effect of adverse cultivation conditions on chlamydospore production. D. flagrans was cultivated on Petri dishes with corn agar for 4 weeks at 27 °C and 70% relative humidity (RH). Four groups were then formed, all with Sabouraud agar as a base, to which different growth inducers were added: GSA (glucose Sabouraud agar), GSA-MI (glucose Sabouraud agar + meso inositol), GSA-E (enriched glucose Sabouraud agar), and AE-M (enriched agar + mannitol). After 4 weeks, chlamydospores were recovered by washing the surface of each plate with distilled water and then quantified. The medium that yielded the highest amount of chlamydospores was subjected to different cultivation conditions: NC (normal conditions): 70% RH and 27 °C, AC (adverse conditions) 1: 20% RH and 40 °C, CA2: 60% RH and 27 °C, and CA3: 55% RH and 24 °C. It was determined that mannitol increases chlamydospore production (65x106 chlamydospores/plate), and when reducing humidity by 10% under cultivation conditions it resulted in an approximately 10% increase in chlamydospore production compared to the control group. These results suggest that the addition of polyols, as well as its cultivation under certain environmental conditions, can improve chlamydospore production on a laboratory scale.

Effect of macrocyclic lactones on nontarget coprophilic organisms: a review.

Macrocyclic lactones are frequently used dewormers in livestock farms around the world. Due to their wide spectrum of action against nematodes and arthropods and their practicality of application at very low doses, their use has become massive since their discovery. These compounds are eliminated in a large percentage in the feces of animals, causing adverse effects on coprophilic fauna. Several research groups around the world have been devoted to evaluating these effects on this fauna. The aim of this review is to register the adverse effects of the concentrations in which macrocyclic lactones are eliminated in the feces of domestic animals and the importance of the coprophilic and edaphilous fauna on the degradation of the feces of the animals. The documented data shows that the use of macrocyclic lactones has a high toxicological risk for the different species that colonize the dung, thus causing an adverse effect on its disintegration and its subsequent incorporation into the soil. Even so, more studies at the regional level and their standardization are necessary to make the comparison between different areas possible.

The use of soy protein polymers as a release device for nematophagous fungi in the control of parasitic nematodes in ruminants.

This trial was conducted to evaluate the predatory activity of Duddingtonia flagrans incorporated into soy protein-based polymers as a controlled-release device (CRD). The rate of fungal release from the polymers and time of residence of the CRD in the rumen of a cannulated sheep was also determined. After administration to the sheep, the CRD was extracted at weekly intervals over a month for observation of its physical structure and faeces were collected to observe the subsequent predatory activity of the fungus in Petri dishes with water-agar 2% and Panagrellus spp. as bait. The CRD slowly degraded in the rumen over 4 weeks and liberated D. flagrans into the faeces. The formulation of the soy protein-based polymers did not affect the predatory activity of the fungus. The study demonstrates that biodegradable soy protein polymers could potentially improve the use of nematophagous fungi for controlling nematode parasites of ruminants.

A rational approach to the regioselective deacetylation of 2',3',5'-tri-O-acetyluridine by Novozym 435 catalysed alcoholysis.

To give a rational explanation for the behaviour of 2',3',5'-tri-O-acetyluridine (TAU) catalysed alcoholysis using Novozym 435, the commercial biocatalyst with immobilized Candida antarctica lipase B (CALB), a set of experiments analyzing the role of the alcohol/substrate (A/S) molar ratio, alcohol/biocatalyst (A/B) and substrate/biocatalyst (S/B) mass ratios were carried out. At a A/S=120 and a S/B=6.16, 2',3'-di-O-acetyluridine (DAU) was obtained in 92% at 22h. The observed trend towards the exclusive formation of DAU at very high alcohol amounts can be explained on the basis of the change of substrate orientation from normal to inverse. The simple molecular modelling analysis supports that key O/H atoms from TAU and the resulting intermediates display the adequate distances to generate productive binding only when the inverse coordination of TAU is present through the 5'-moiety of TAU, at high ethanol concentrations. At these conditions a possible allosteric-like effect of ethanol, combined with water in an H-network in the catalytic triad and in its neighbourhood, could explain the high selectivity towards the production of DAU at selected conditions.

Environmental impact of ivermectin excreted by cattle treated in autumn on dung fauna and degradation of faeces on pasture.

The effect of ivermectin excreted in faeces of treated cattle on dung fauna and dung degradation on pasture during autumn was evaluated. Two groups of calves were used. One group was treated subcutaneously with ivermectin while the other remained as untreated control. Faeces deposited on 1, 3, 7, 14 and 21 days post-treatment (dpt) were removed on 1, 3, 7, 14, 21, 30 and 60 days post-deposition (dpd) and were used to determine the concentration of ivermectin and the percentage of organic matter and for the collection of colonising organisms. Samples from 1 and 3 dpt contained the highest drug concentration and percentage of organic matter compared to the control group (p<0.05). Faeces from the treated group showed lesser abundance and diversity of arthropods (p<0.05) than the control group. A reduction in numbers and diversity of dung fauna in faecal samples from treated animals was most remarkable at 1, 3 and 7 dpt, coinciding with the highest concentration of ivermectin and organic matter percentage.