Use of Arthrobotrys spp. in biocontrol of the root-knot nematode Meloidogyne incognita

Plant parasitic nematodes are well-known and devastating pathogens of many agricultural crops around the world. Among the plant phytoparasitic, root-knot nematodes (Meloidogyne spp.) are the economically important limiting factors in agricultural productivity and the quality of crops. One of the most destructive species of root-knot nematodes is Meloidogyne incognita among the most important plant pests which cause severe problems in economically important crops such as vegetables, fruits, and ornamental plants. Root-knot nematodes can be managed by resistant cultivars, crop rotation, cultural practices, chemical nematicides and biocontrol agents. However, the use of nematicides can cause significant problems, including environmental pollution and long-term residue issues. Therefore, biological control with fungus is agriculturally useful an exciting and rapidly developing research area and especially there is growing attention to the exploitation of fungi for the control of nematodes. Nematophagous fungi are an important group of soil microorganisms that can suppress the populations of plant parasitic nematodes. These fungi can be divided into four main categories: endoparasitic fungi, nematode-trapping fungi, fungi that parasitic egg and female, and toxin-producing fungi. Among the nematophagous fungi, nematode-trapping fungi which are natural enemies of nematodes are the most studied. The nematode-trapping fungi develop hyphal structures. Arthrobotrys spp. are a well-known nematode-trapping fungus with biocontrol potential against root-knot nematodes, including M. incognita. The objective of this paper is to summarize the data on the potential for use of Arthrobotrys spp. in biocontrol of the root-knot nematode M. incognita. DOI: http://dx.doi.org/10.5281/zenodo.1001564

Purification and Properties of Polyphenol Oxidase of Dried <i>Volvariella bombycina</i>

Polyphenol oxidase (PPO) was purified and characterized from a dried wild edible and medicinal mushroom (V. bombycina). Using Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity chromatography, PPO was purified from the dried V. bombycina. The purification was completed with a 33.85-fold purification. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the purified enzyme migrated as a single band. The molecular weight of the purified enzyme was estimated by SDS-PAGE to be about 25 kDa. Catechol, 4-methyl catechol, and pyrogallol were used as substrates to determine the enzyme activity and its kinetic parameters (Km and Vmax). At the optimum pH and temperature, dried V. bombycina PPO’s Km and Vmax values for catechol, 4-methyl catechol, and pyrogallol were found to be 1.67 mM–833.33 U/mL, 3.17 mM–158.73 U/mL, and 2.67 mM–3333.33 U/mL, respectively. Also investigated were the effects of pH and temperature on the enzymatic properties of PPO in dried V. bombycina. The optimum pH and temperature values for dried V. bombycina PPO obtained by using catechol, 4-methyl catechol, and pyrogallol as substrates were 6.5, 15 °C; 9.0, 20 °C; and 8.0, 15°C, respectively. This is the first study on the purification and characterization of PPO from dried V. bombycina