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We report the isolation of a bacterium from Galleria mellonella larva and its identification using genome sequencing and phylogenomic analysis. This bacterium was named Alcaligenes faecalis strain MOR02. Microscopic analyses revealed that the bacteria are located in the esophagus and intestine of the nematodes Steinernema feltiae, S. carpocapsae, and H. bacteriophora. Using G. mellonella larvae as a model, when the larvae were injected with 24,000 CFU in their hemocoel, more than 96% mortality was achieved after 24 h. Additionally, toxicity assays determined that 1 μg of supernatant extract from A. faecalis MOR02 killed more than 70% G. mellonella larvae 96 h after injection. A correlation of experimental data with sequence genome analyses was also performed. We discovered genes that encode proteins and enzymes that are related to pathogenicity, toxicity, and host/environment interactions that may be responsible for the observed phenotypic characteristics. Our data demonstrates that the bacteria are able to use different strategies to colonize nematodes and kill insects to their own benefit. However, there remains an extensive group of unidentified microorganisms that could be participating in the infection process. Additionally, a nematode-bacterium association could be established probably as a strategy of dispersion and colonization.

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Pesticides are by no means a new invention. In fact, intentional pesticide use goes back thousand years when Sumerians, Greeks, and Romans killed pests using various compounds such as sulphur, mercury, arsenic, copper or plant extracts. However, results were frequently poor because of the primitive chemistry and the insufficient application methods. A rapid emergence in pesticide use began mainly after World War II with the introduction of DDT (dichlorodiphenyltrichloroethane), BHC (benzene hexachloride), aldrin, dieldrin, endrin, and 2,4-D (2,4-dichlorophenoxyacetic acid). These new chemicals were effective, easy to use, inexpensive, and thus enormously popular. However, under constant chemical pressure, some pests became genetically resistant to pesticides, non-target organisms were harmed, and pesticide residues often appeared in unexpected places [3]. Chemical pesticides can be classified in different ways, but one of the most used is according to their chemical composition, which allows to group pesticides in a uniform and scientific way and to establish a correlation between structure, activity, toxicity and degradation mechanisms, among others. Table 1 shows the most important pesticides according to their chemical composition. Some general characteristics of pesticides are shown in Table 2. Group Main composition Organochlorine Carbon atoms, chlorine, hydrogen and occasionally oxygen. They are nonpolar and lipophilic Organophosphate Possess central phosphorus atom in the molecule. In relation whit organochlorines, these compounds are more stable and less toxic in the environment. The organophosphate pesticides can be aliphatic, cyclic and heterocyclic. Carbamates Pesticides Characteristics Examples Organochlorines Soluble in lipids, they accumulate in fatty tissue of animals, are transferred through the food chain; toxic to a variety of animals, longterm persistent. DDT, aldrin, lindane, chlordane, mirex. Organophosphates Soluble in organic solvents but also in water. They infiltrate reaching groundwater, less persistent than chlorinated hydrocarbons; some affect the central nervous system. They are absorbed by plants, transferred to leaves and stems, which are the supply of leaf-eating insects or feed on wise. Malathion, methyl parathion, diazinon Carbamates Carbamate acid derivatives; kill a limited spectrum of insects, but are highly toxic to vertebrates. Relatively low persistence Sevin, carbaryl Pyrethroids Affect the nervous system; are less persistent than other pesticides; are the safest in terms of their use, some are used as household insecticides. Pyrethrins Biological Only the Bacillus thuringiensis (Bt) and its subspecies are used with some frequency; are applied against forest pests and crops, particularly against butterflies. Also affect other caterpillars.

Biodegradation of some organochlorine and organophosphate pesticides is difficult because of their low solubility in water and, therefore, their low bioavailability. To overcome the hydrophobicity problem and the limited pesticide availability, biosurfactants play a major role. In this study, we evaluated the effect of an extract from Pseudomonas sp. B0406 strain with surfactant properties, on the solubility of two pesticides: endosulfan (ED) and methyl parathion (MP). Such a process was performed in order to increase the aqueous solubility of both pesticides, to increase its availability to microorganisms and to promote their biodegradation. The extract from Pseudomonas sp. B0406 showed a critical micellar concentration of 1.4 g/L and the surface tension at that point was 40.4 mN/m. The preliminary chemical and physical partial characterization of the extract with surfactant properties indicated that it is an anionic glycolipid, which increases the solubility of both pesticides of 0.41 at 0.92 mg/L for ED and of 34.58 at 48.10 mg/L for MP. The results of this study suggest the effectiveness of this extract in improving the solubility of both pesticides ED and MP in water and, therefore, of its potential use to enhance the degradation of these pesticides.