Search

Plastic production has been increasing exponentially in the last 60 years, but plastic disposal is out of control, resulting in the pollution of all ecosystems on Earth. Finding alternative environmentally sustainable choices, such as biodegradation by insects and their associated gut microbiota, is crucial, however we have only begun to characterize these ecosystems. Some bacteria and one fungus have been previously identified in the gut of Greater Wax Moth larvae (Galleria mellonella L., Lepidoptera, Pyralidae) located mainly in the Northern hemisphere. The aim of this study was to describe changes in the gut microbiota associated with the consumption of polyethylene and polystyrene by the Greater Wax Moth in Argentina, considering both bacteria and fungi. Larvae were fed polyethylene, polystyrene and beeswax as control for 7 days. Next generation sequencing revealed changes in the bacterial gut microbiome of the wax moth larvae at the phyla and genus levels, with an increase in two Pseudomonas strains. The fungal communities showed no differences in composition between diets, only changing in relative abundance. This is the first report of both bacterial and fungal communities associated with a plastivore insect. The results are promising and call for more studies concerning a potential multi-kingdom synergy in the plastic biodegradation process. [ABSTRACT FROM AUTHOR]

The genus Streptomyces comprises a group of bacteria species with high economic importance. Several of these species are employed at industrial scale for the production of useful compounds. Other characteristic found in different strains within this genus is their capability to tolerate high level of substances toxic for humans, heavy metals among them. Although several studies have been conducted in different species of the genus in order to disentangle the mechanisms associated to heavy metal resistance, little is known about how they have evolved along Streptomyces phylogeny. In this study we built the largest Streptomyces phylogeny generated up to date comprising six genes, 113 species of Streptomyces and 27 outgroups. The parsimony-based phylogenetic analysis indicated that (i) Streptomyces is monophyletic and (ii) it appears as sister clade of a group formed by Kitasatospora and Streptacidiphilus species, both genera also monophyletic. Streptomyces strains resistant to heavy metals are not confined to a single lineage but widespread along Streptomyces phylogeny. Our result in combination with genomic, physiological and biochemical data suggest that the resistance to heavy metals originated several times and by different mechanisms in Streptomyces history., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Twelve Bacillus thuringiensis (Bt) strains, isolated from larvae and soil samples in Argentina, were molecularly and phenotypically characterized and their insecticidal activities against Spodoptera frugiperda and Peridroma saucia were determined. One isolate--Bt RT--produced more than 93% mortality on first instar larvae of both species, which was higher than that produced by the reference strain Bt 4D1. Bt RT carried a different cry gene profile than Bt 4D1. Scanning electron microscopy showed the presence of bipyramidal and cuboidal crystals. Phenotypic characterization revealed lytic enzymes that could contribute to Bt pathogenicity.

Fourteen strains of Bacillus thuringiensis collected from both larvae showing disease symptoms and soil samples in northwest Argentina were characterized by insecticidal activity against Spodoptera frugiperda. First instar larvae and protein profile SDS-PAGE analysis of whole cell proteins not only allowed the differentiation of native Bacillus thuringiensis but also revealed the possibility of applying protein profile analysis in classification of toxicity patterns. Cluster analysis showed that there were two main groups. Interestingly, one of them only contained the most pathogenic native strains. The biomass-bound protease activity of native pathogenic isolates and the reference strain Bt 4D1 is also reported.