AUTHOR=Rocha Francine Yuriko Otsuka , Negrisoli Júnior Aldomário Santo , de Matos Gustavo Feitosa , Gitahy Patrícia de Medeiros , Rossi Carolina Nachi , Vidal Marcia Soares , Baldani José Ivo 

TITLE=Endophytic Bacillus Bacteria Living in Sugarcane Plant Tissues and Telchin licus licus Larvae (Drury) (Lepidoptera: Castniidae): The Symbiosis That May Open New Paths in the Biological Control

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.659965

DOI=10.3389/fmicb.2021.659965

ISSN=1664-302X

ABSTRACT=<p>Bacteria of the genus <italic>Bacillus</italic> can colonize endophytically and benefit several crops including the control of some pest orders. In view of the benefits provided by these microorganisms and in order to find out an efficient biotechnological control for the giant borer, our interest in studying the microorganisms in symbiosis with sugarcane and the giant borer has arisen, since there is no efficient chemical or biological control method for this pest. Therefore, endophytic <italic>Bacillus</italic> strains were isolated from three sugarcane niches (apoplast fluid, central internode cylinder and roots) and also from the giant borer larvae living inside sugarcane varieties grown in the Northeast region of Brazil. The taxonomical characterization (16S rRNA) of 157 Gram-positive isolates showed that 138 strains belonged to the <italic>Bacillus</italic> genus. The most representative species were phylogenetically closely related to <italic>B. megaterium</italic> (11.5%) followed by <italic>B. safensis</italic> (10.8%), <italic>B. cereus</italic> (8.9%), <italic>B. oleronius</italic> (8.9%), <italic>B. amyloliquefaciens</italic> (7.0%), and <italic>B. pacificus</italic> (6.4%). BOX-PCR analyses showed very distinct band pattern profiles suggesting a great diversity of <italic>Bacillus</italic> species within the sugarcane niches and the digestive tract, while the <italic>B. cereus</italic> group remained very closely clustered in the dendrogram. According to XRE biomarker analysis, eleven strains (FORCN005, 007, 008, 011, 012, 014, 067, 076, 092, 093, and 135) correspond to <italic>B. thuringiensis</italic> species. Additional studies using conserved genes (<italic>glp</italic>, <italic>gmk</italic>, <italic>pta</italic>, and <italic>tpi</italic>) indicated that most of these strains were phylogenetically closely related to <italic>B. thuringiensis</italic> and may be considered different subspecies. In conclusion, this study suggests that the culturable <italic>Bacillus</italic> species are greatly diversified within the plant niches and showed <italic>Bacillus</italic> species in the digestive tract of the giant borer for the first time. These results open new perspectives to understand the role and functions played by these microorganisms in symbiosis with this pest and also the possibility of developing an efficient biological control method for the giant borer using strains identified as the <italic>B. thuringiensis</italic> species.</p>