Diversidade microbiana e estocagem do alimento em Cornitermes cumulans (Isoptera: Termitidae)
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Data
2017-03-02
Autores
Menezes, Letícia Ramos de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O bioma Cerrado possui uma das termitofaunas mais diversas do mundo. Cornitermes cumulans é um cupim neotropical conhecido pela construção de ninhos em montículos e por armazenar alimento no núcleo celulósico do ninho. Apesar de ser considerado uma espécie-chave do Cerrado, aspectos básicos da biologia deste cupim não estão esclarecidos, principalmente em relação à fisiologia da sua alimentação e seu comportamento de forrageamento. A simbiose entre cupins superiores e bactérias é considerada essencial para a sobrevivência destes insetos, pois tem papel fundamental na digestão do alimento consumido por estes insetos. No entanto, os ninhos de cupins também possuem uma grande variedade de microrganismos presentes nas paredes destas estruturas, os quais podem estar ou não diretamente associados com a digestão lignocelulósica. Atualmente, análises moleculares têm relevado novas informações sobre os mecanismos de digestão da lignocelulose no intestino de cupins. Contudo, esses estudos não consideram os microrganismos associados ao alimento armazenado no interior dos ninhos e seu papel na biologia de cupins. Em vista do exposto, a presente pesquisa investigou aspectos da coleta do alimento e dinâmica do forrageamento de C. cumulans sob condições laboratoriais por meio de bioensaios. Adicionalmente buscou-se comparar morfologicamente e morfometricamente uma população de operários coletada no interior do ninho com uma população forrageira, levando-se em conta principalmente o desgaste das mandíbulas. Adicionalmente, o presente estudo teve como objetivo compreender a estocagem de alimento por Cornitermes cumulans, do ponto de vista bioquímico, por meio de testes de atividade enzimática; e molecular, por meio do sequenciamento do gene 16S rRNA. Neste contexto, hipotetizamos que esta espécie armazena o alimento para facilitar a degradação da lignocelulose antes da ingestão do mesmo. A análise da dinâmica do forrageamento mostrou que a casta operária é responsável pela descoberta do alimento e recrutamento dos companheiros do ninho. Nas condições laboratoriais testadas, um operário pioneiro de C. cumulans levou 30,72 ± 16,75 min para descobrir a fonte alimentar e iniciar o recrutamento. Iniciado o recrutamento, cerca de 10 minutos depois foi considerado recrutamento massivo pelo aumento significativo no recrutamento de companheiros de ninho, e após cerca de 25 minutos, o recrutamento se tornou estável. Este processo de recrutamento em fases também ocorre em espécies do gênero Nasutitermes e até mesmo espécies de cupins subterrâneos como Coptotermes gestroi. Além disso, o presente estudo comprovou, por meio de bioensaio, a teoria de que C. cumulans armazena alimento no ninho e que amostras de operários forrageiros diferem daquelas coletadas no interior do ninho, principalmente pelo desgaste das mandíbulas. A análise enzimática revelou que o extrato bruto dos operários e soldados de C. cumulans é capaz de degradar substratos naturais e sintéticos, como β-glucano e pNP-G, sugerindo a atividade de enzimas das famílias GH 1; 3 (β-glicosidase) 9; 16 (endo- β-1,4-glucanase). Adicionalmente, o extrato bruto do alimento armazenado por esta espécie comportou-se de forma complementar, degradando substratos derivados de hemiceluloses, como xilano e arabinoxilano, indicando a atividade de enzimas das famílias GH 3; 8; 10; 11; 31; e 35 (β-1,4-xilosidases, endo-β-1,3:1,4-xilanases, β-galactosidases e α-galactosidases). A diversidade microbiana mostrou que o alimento armazenado e o material da parede do ninho apresentam comunidades microbióticas semelhantes, predominando bactérias do filo Actinobacteria e Proteobacteria, conhecidas pela capacidade celulolítica, hemicelulolítica e fixação de nitrogênio. Adicionalmente, a microbiota intestinal foi primariamente dominada por Spirochaetes (Treponema sp: Spirochaetes) em C. cumulans e Firmicutes (Candidatus Arthromitus: Clostridia) em Procornitermes araujoi. Estes filos apresentam espécies conhecidas pela fixação de nitrogênio atmosférico como meio de enriquecimento de dietas pobres em nitrogênio e fermentação do carboidrato através da acetogênese como forma de obtenção de energia, respectivamente. A partir dos dados apresentados, pode-se concluir que a espécie Cornitermes cumulans apresenta uma dinâmica de forrageamento em fases e que armazena alimento no interior de seu ninho. Tal alimento armazenado por C. cumulans e sua microbiota hemicelulolítica associada aumentam a capacidade de assimilação de outros componentes da biomassa vegetal por este cupim, garantindo a ele uma vantagem em relação às espécies que não possuem o hábito de armazenar alimento no interior do ninho, como P. araujoi.
The Cerrado biome has one of the most diverse termitofaunas in the world. Cornitermes cumulans is a neotropical termite known for building nests in mounds and store food in the cellulosic core nest. Although it is considered a key species of the Cerrado, basic aspects of the biology of this termite are not clarified, mainly in relation to the physiology of its feeding and its foraging behavior. The symbiosis between upper termites and bacteria is considered essential for the survival of these insects, since it plays a fundamental role in the digestion of the food consumed by these insects. However, termite nests also have a wide variety of microorganisms present on the walls of these structures, which may or may not be directly associated with lignocellulosic digestion. Currently, molecular analyzes have revealed new information on the mechanisms of digestion of lignocellulose in the intestine of termites. However, these studies do not consider the microorganisms associated with food stored inside the nests and their role in termite biology. In view of the above, the present study investigated aspects of food gathering and foraging dynamics of C. cumulans under laboratory conditions using bioassays. In addition, we sought to compare morphometrically and morphometrically a population of workers collected inside the nest with a forage population, taking into account mainly the wear of the jaws. Additionally, prosente study aimed to understand the food storage for Cornitermes cumulans, the biochemical point of view, by means of enzyme activity tests; And molecular, by sequencing the 16S rRNA gene. In this context, we hypothesized that this species stores the food to facilitate the degradation of lignocellulose before its ingestion. The analysis of the foraging dynamics showed that the caste worker is responsible for the discovery of food and recruitment of the companions of the nest. In laboratory conditions tested, a pioneer worker C. cumulans took 30.72 ± 16.75 min to find the food source and start recruiting. Initiated recruitment, about 10 minutes later was considered massive recruitment by the significant increase in recruitment of nest mates, and after about 25 minutes, recruitment became stable. This recruitment process in phases also occurs in the genus Nasutitermes and even species of subterranean termites such as Coptotermes gestroi. Furthermore, this study demonstrated by means of bioassay, the theory that C. cumulans stores food in the nest and feed samples differ from those workers collected within the nest, particularly by wear of the jaws. Enzyme analysis revealed that the crude extract of the workers and C. cumulans soldiers is capable of degrading natural and synthetic substrates such as β-glucan and pNP-G, suggesting the activity of enzymes of GH families 1; 3 (β-glycosidase) 9; 16 (endo-β-1,4-glucanase). Additionally, the crude extract of the food stored by this species behaved in a complementary way, degrading substrates derived from hemicelluloses, such as xylan and arabinoxylan, indicating the activity of enzymes of GH 3 families; 8; 10; 11; 31; And 35 (β-1,4-xylosidases, endo-β-1,3: 1,4-xylanases, β- galactosidases and α-galactosidases). The microbial diversity showed that the stored food and the material of the wall of the nest present similar microbiotic communities, predominating bacteria of the phylum Actinobacteria and Proteobacteria, known for the cellulolytic, hemicellulolytic and nitrogen fixation capacity. In addition, the intestinal microbiota was primarily dominated by Spirochaete (Treponema sp: Spirochaetes) C. cumulans and Firmicutes (Candidatus Arthromitus: Clostridia) in Procornitermes araujoi. These phyla present species known by the fixation of atmospheric nitrogen as a means of enriching diets low in nitrogen and fermentation of the carbohydrate through the acetogenesis as a way of obtaining energy, respectively. From the data presented, it can be concluded that the species Cornitermes cumulans presents a foraging dynamics in phases and that stores food inside its nest. Such food stored by C. cumulans and their associated microbiota hemicelulolítica increase the assimilative capacity of other components of plant biomass by this termite, ensuring him an advantage over species that do not have the habit of storing food inside the nest, as P. araujoi.
The Cerrado biome has one of the most diverse termitofaunas in the world. Cornitermes cumulans is a neotropical termite known for building nests in mounds and store food in the cellulosic core nest. Although it is considered a key species of the Cerrado, basic aspects of the biology of this termite are not clarified, mainly in relation to the physiology of its feeding and its foraging behavior. The symbiosis between upper termites and bacteria is considered essential for the survival of these insects, since it plays a fundamental role in the digestion of the food consumed by these insects. However, termite nests also have a wide variety of microorganisms present on the walls of these structures, which may or may not be directly associated with lignocellulosic digestion. Currently, molecular analyzes have revealed new information on the mechanisms of digestion of lignocellulose in the intestine of termites. However, these studies do not consider the microorganisms associated with food stored inside the nests and their role in termite biology. In view of the above, the present study investigated aspects of food gathering and foraging dynamics of C. cumulans under laboratory conditions using bioassays. In addition, we sought to compare morphometrically and morphometrically a population of workers collected inside the nest with a forage population, taking into account mainly the wear of the jaws. Additionally, prosente study aimed to understand the food storage for Cornitermes cumulans, the biochemical point of view, by means of enzyme activity tests; And molecular, by sequencing the 16S rRNA gene. In this context, we hypothesized that this species stores the food to facilitate the degradation of lignocellulose before its ingestion. The analysis of the foraging dynamics showed that the caste worker is responsible for the discovery of food and recruitment of the companions of the nest. In laboratory conditions tested, a pioneer worker C. cumulans took 30.72 ± 16.75 min to find the food source and start recruiting. Initiated recruitment, about 10 minutes later was considered massive recruitment by the significant increase in recruitment of nest mates, and after about 25 minutes, recruitment became stable. This recruitment process in phases also occurs in the genus Nasutitermes and even species of subterranean termites such as Coptotermes gestroi. Furthermore, this study demonstrated by means of bioassay, the theory that C. cumulans stores food in the nest and feed samples differ from those workers collected within the nest, particularly by wear of the jaws. Enzyme analysis revealed that the crude extract of the workers and C. cumulans soldiers is capable of degrading natural and synthetic substrates such as β-glucan and pNP-G, suggesting the activity of enzymes of GH families 1; 3 (β-glycosidase) 9; 16 (endo-β-1,4-glucanase). Additionally, the crude extract of the food stored by this species behaved in a complementary way, degrading substrates derived from hemicelluloses, such as xylan and arabinoxylan, indicating the activity of enzymes of GH 3 families; 8; 10; 11; 31; And 35 (β-1,4-xylosidases, endo-β-1,3: 1,4-xylanases, β- galactosidases and α-galactosidases). The microbial diversity showed that the stored food and the material of the wall of the nest present similar microbiotic communities, predominating bacteria of the phylum Actinobacteria and Proteobacteria, known for the cellulolytic, hemicellulolytic and nitrogen fixation capacity. In addition, the intestinal microbiota was primarily dominated by Spirochaete (Treponema sp: Spirochaetes) C. cumulans and Firmicutes (Candidatus Arthromitus: Clostridia) in Procornitermes araujoi. These phyla present species known by the fixation of atmospheric nitrogen as a means of enriching diets low in nitrogen and fermentation of the carbohydrate through the acetogenesis as a way of obtaining energy, respectively. From the data presented, it can be concluded that the species Cornitermes cumulans presents a foraging dynamics in phases and that stores food inside its nest. Such food stored by C. cumulans and their associated microbiota hemicelulolítica increase the assimilative capacity of other components of plant biomass by this termite, ensuring him an advantage over species that do not have the habit of storing food inside the nest, as P. araujoi.
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Palavras-chave
Térmita, Armazenamento de alimento, Cupins superiores, 16S rRNA, Cupins forrageiros, Comportamento