Banca de DEFESA: RODRIGO JOSE NUNES CALUMBY

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : RODRIGO JOSE NUNES CALUMBY
DATE: 15/10/2021
TIME: 08:30
LOCAL: Vìdeoconferência
TITLE:

Characterization of cultivable intestinal microbiota in Rhynchophorus palmarum Linnaeus (Coleoptera: Curculionidae) and determination of cellulolytic activity

KEY WORDS:

Rhynchophorus palmarum L.; Cocos nucifera; intestinal microbiota; MALDI-TOF; biological control; cellulose; Thielaviopsis paradoxa.

PAGES: 111
BIG AREA: Ciências Biológicas
AREA: Microbiologia
SUBÁREA: Microbiologia Aplicada
SUMMARY:

Rhynchophorus palmarum L. is an agricultural pest that affects various palm crops, including coconut (Cocos nucifera) plantations which are prominent in the economy of Northeastern Brazil. Characterization of the intestinal microbiota of R. palmarum, as well as elucidation of aspects related to the biochemistry and physiology of the insect's digestion are essential for intervention in specific metabolic processes as a form of pest control. This study aimed to characterize the intestinal microbiota of R. palmarum and investigate its ability to degrade cellulosic substrates, in order to explore new biological control measures. Intestinal dissections of eight adult insects (4 males and 4 females) of R. palmarum captured in the field was performed in a laminar flow chamber. The intestines were then inserted into brain heart infusion (BHI) broth and incubated at ± 35°C for 24 hours. Subsequently, serial dilutions (10-1 to 10-6) of these cultures were plated on nutritious culture media for the isolation of bacteria and fungi. The microorganisms were identified by MALDI-TOF mass spectrometry, and subsequently evaluated for their ability to degrade cellulose as a carbon source in a solid culture medium containing carboxymethylcellulose. The research of T. paradoxa was carried out from the culture of R. palmarum carapace and digestive tract samples captured in the field (n = 20) on potato dextrose agar plus chloramphenicol. As a result, 20 microorganisms were identified, corresponding to 16 bacterial (Acinetobacter, Alcaligenes, Arthrobacter, Bacillus, Citrobacter, Enterococcus, Kerstersia, Lactococcus, Micrococcus, Proteus, Providencia, Pseudomonas, Serratia and Staphylococcus) and fungal (Candida e Saccharomyces), which have been found in Phyla Firmicutes, Actinobacteria, Proteobacteria and Ascomycota. The intestinal microbiotas proved to be quite diversified with few differences observed between the sexes. Regarding the species identified, Enterococcus faecalis was more abundant both in male insects (25.3%) and in females (47.1%), followed by Citrobacter koseri (15.2%) and Alcaligenes faecalis (8.8%) in males and Bacillus cereus (10.4%) and Citrobacter koseri (4.4%) in females. Six bacterial and one fungal species showed cellulolytic activity, with emphasis on Bacillus cereus, which showed high enzyme synthesis (IE = 4.6). The isolations made from the carapace of R. palmarum showed 15.0% of mycelial growth of T. paradoxa, corresponding to three infected insects. T. paradoxa was not found in the intestinal tract of insects. This is the first worldwide study on the characterization of the intestinal microbiota of R. palmarum, composed mainly of facultative microorganisms with fermentative metabolism capable of degrading plant polysaccharides, which can play an important role in insect nutrition. These findings open interesting perspectives for the development of new strategies for the symbiotic control of R. palmarum.

BANKING MEMBERS:
Interna - 1527220 - CAMILA BRAGA DORNELAS
Interno - 1653558 - LUCIANO APARECIDO MEIRELES GRILLO
Externo ao Programa - 1653165 - VALTER ALVINO DA SILVA
Externa à Instituição - LARA MENDES DE ALMEIDA - USP