Integral Characterization of the 16S rRNA Gene of Non-sporulating Bacteria and Its Action Against Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae)

Abstract

Brazil is the world’s largest producer of soybean (Glycine max), an extremely important legume due to its source of proteins and essential oils for humans and animals, besides to its applications in the various branches of industry. The velvetbean caterpillar [Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae)] is a great pest that affects this crop and has been controlled by chemical and biological pesticides based on Bacillus thuringiensis. The objectives of this work were to prospect soil microorganisms, to characterize them using the 16S rRNA gene and to perform bioassays to analyze the lethality or subletality of these isolates against A. gemmatalis larvae. The DNA sequencing of the marker gene was complete, covering all conserved regions of it to determine the phylogenetic position of the isolates. Regarding to bioassays, subletality efficacy were low both for sporulant and for the non-sporulant bacterial strains tested. However, based on the signature by complete 16S rRNA analyses of the non-sporulating bacterial isolates, new characteristics worth of studying and prospecting biotechnologically became available.

Taxonomy of Non-sporulating Bacteria Tested in Biological Control Against Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae)

“…The taxonomic characterization based on complete DNA sequencing of 16S rRNA for non-sporulating bacteria performed by Alves (2020) were also more accurate than those based on partial DNA sequencing (Almeida, 2017). Apart from genus classification, complete DNA sequencing of ribosomal gene brings classification in the level of species in this work as in the work of Alves (2020). For isolates LGA-V0513, LGA-V056, LGA-V20C,…”

“…LGA-V20F, LGA-V0522, the reliable classification was as follow, respectively: Bacillus toyonensis, Novosphingobium lindaniclasticum, Rhizobium vallis, Cupriavidus necator and Chromobacterium vacinni (Alves, 2020).…”

“…Bootstrap and SH-aLRT branch tests applied the ML nucleotide frequency optimization, Ultrafast bootstrap analysis and 1,000 replicates options. The taxonomic classification of non-sporulating bacterial isolates LGA-V0513, LGA-V056, LGA-V20C, LGA-V20F, LGA-V0522 were processed by Alves et al (2020).…”

“…The 16s rRNA molecular marker is spread in all bacterial species and can be used for taxonomic purposes due its conserved and hypervariable regions developed during evolution. Applying this widely used marker it is possible to characterize a bacterium at the level of genus and species, allowing the prospection of its biotechnological potentials (Menna et al, 2006;Alves et al, 2020). Thus, this work aimed to taxonomic characterization and bioprospecting of non-sporulating bacterial isolates from soil vewing the entomopathogenic potential against S. frugiperda, compared to B. thuringiensis strains.…”