Molecular characterization of cultivable bacteria associated with adult Schistocerca gregaria, using 16S rRNA

Abstract

S. gregaria is able to swarm and disseminate bacterial load over vast areas. Adult locusts were collected from Kingdom of Saudi Arabia (KSA), individual locust was divided into head, thorax and abdomen. External and internal cultivable bacteria were cultured, cell and colony characteristics were investigated. Pure colonies were sequenced using 16S rRNA. Sequences and phylogeny were analyzed. Using morphological and molecular results, 9 bacterial genera belonging to 5 families, 3 orders, 2 classes, and 2 phyla were recorded. Ribosomal Database Project (RDP) Classifier succeeded to confirm 8 out of 9 genera. The ninth isolate was designated as unclassified. To specify a genus to its closest species, 16S rRNA genes of the type species have been downloaded. Phylogenetic tree was generated using all available sequences. Similarity measures and phylogenetic trees were used to place each genus to its closest species. Six genera created similarities less than 98% to related species. Generally, analyses of 16S rRNA gene succeeded to identify 3 isolates to species level, 5 isolates to genus level and designated one isolate “unclassified”. Investigations are recommended to place all genera to their operational taxonomic units (OTU). Significance of our findings relies on the impact of locust-microbiota on heath of people who consumed insects as food. Bacterial species which were internally, isolated from abdomen were described beneficial commensals. Bacterial species which were internally, isolated from thorax and head were described non-pathogenic beneficial endosymbionts, except Bacillus sp. Salmonella sp. was isolated as external species and was described external contaminant of the locust.

Keywords

• locust
• s. gregaria
• dna sequencing
• 16s rrna gene
• bacterial identification