Genômica aplicada à predição dos mecanismos moleculares de resistência aos metais potencialmente tóxicos e promoção de crescimento vegetal em Rhizobium sp. LBMP-C04
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Data
2021-09-14
Autores
Bonaldi, Daiane Silva
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Universidade Estadual Paulista (Unesp)
Resumo
A associação de microrganismos com plantas hiperacumuladoras de metais potencialmente tóxicos (MPT) para remover, transferir ou estabilizar esses elementos do solo é uma ferramenta adequada para processos de biorremediação de ambientes contaminados. A capacidade dos microrganismos em resistir a esses ambientes depende de fatores bioquímicos, estruturais, fisiológicos e de adaptação genética deles. Sendo assim, o objetivo desde trabalho consiste na avaliação da capacidade do isolado Rhizobium sp. LBMP-C04 em ser usado para biorremediação e promoção de crescimento vegetal em solos contaminados com metais. Para isso, nesse trabalho foi realizada a predição de genes relacionados ao metabolismo de MPT, genes de promoção de crescimento e genes de resistência a antimicrobianos, bem como a realização de testes bioquímicos para comprovar essas características in vitro da bactéria Rhizobium sp. LBMP-C04. Através das anotações funcionais do genoma sequenciado foi possível predizer uma variedade de genes relacionados à resistência aos MPT, de promoção de crescimento vegetal e resistência a antimicrobianos no genoma bacteriano. Os genes de resistência estão associados principalmente a mecanismos relacionados a bombas de efluxo, reparo de danos ao DNA e na importação ou exportação de metal nas células bacterianas, a fim de manter a homeostase celular. Os genes que promovem o crescimento vegetal estão relacionados com os mecanismos de tolerância ao estresse osmótico, solubilização de fosfato, metabolismo do nitrogênio, fixação biológica de nitrogênio, formação de biofilme, respostas ao choque térmico e a biossíntese de ácido indol-3-ácetico (AIA), de triptofano e de ácidos orgânicos. Os resultados bioquímicos indicam que o isolado Rhizobium sp. LBMP-C04 é capaz de solubilizar fosfato de cálcio, produzir sideróforos e compostos indólicos in vitro; o isolado foi resistente aos antibióticos ampicilina, amoxicilina, rifampicina, ácido nalidíxico e trimetropina. O isolado Rhizobium sp. LBMP-C04 apresentou MIC de 5, 14, 13, 12, 48 e 401 mmol dm-3 respectivamente aos metais Cd2+, Cu2+, Cr6+, Cr3+, Zn2 e Ni2+, além de ter sido detectado acúmulo intracelular desses metais, demostrado pela remoção de metais do meio de cultivo e por microscopia eletrônica de transmissão. Os resultados observados indicam a possibilidade de se utilizar o isolado Rhizobium sp. LBMP-C04 como uma bactéria eficiente em processos de biorremediação e fitorremediação de ambientes contaminados por metais potencialmente tóxicos por apresentar resistência a diversos metais e ter possibilidade de atuar como promotora de crescimento em plantas bioacumuladoras
The association of microorganisms with hyperaccumulating plants of potentially toxic metals (PTM) to remove, transfer or stabilize these elements from the soil is a suitable tool for bioremediation processes in contaminated environments. The ability of microorganisms to resist these environments depends on biochemical factors, physiological adaptations and their genetic adaptation. Therefore, the objective of this work is to evaluate the isolation capacity of Rhizobium sp. LBMP-C04 to be used for bioremediation and plant growth promotion in metal contaminated soils. For this purpose, in this work a prediction of genes related to PTM metabolism, growth promotion genes and antimicrobial resistance genes was performed, as well as the performance of biochemical tests to prove these characteristics in vitro of the bacterium Rhizobium sp. LBMP-C04. Through the linked annotations of the sequenced genome, it was possible to predict a variety of genes related to PTM resistance, plant growth promotion and antimicrobial resistance in the bacterial genome. Resistance genes are mainly associated with components related to efflux pumps, repair of DNA damage and the import or export of metal in bacterial cells, in order to maintain cell homeostasis. Genes that promote plant growth are related to mechanisms of osmotic stress tolerance, phosphate solubilization, nitrogen metabolism, biological nitrogen correction, biofilm formation, heat shock responses and indole-3-acetic acid biosynthesis (IAA), tryptophan and organic acids. The biochemical results indicate that the isolate Rhizobium sp. LBMP-C04 is able to solubilize calcium phosphate, produce siderophores and indole compounds in vitro; o was an isolate resistant to the antibiotics ampicillin, amoxicillin, rifampicin, nalidixic acid and trimethoppine. The isolate Rhizobium sp. LBMP-C04 presented MIC of 5, 14, 13, 12, 48 and 401 mmol dm-3 respectively to the metals Cd2+, Cu2+, Cr6+, Cr3+, Zn2 , and Ni2+, in addition to having detected intracellular accumulation of these, demonstrated by metal metals metals in the culture medium and by transmission electron microscopy. The observed results indicate the possibility of using the isolate Rhizobium sp. LBMP-C04 as an efficient bacterium in bioremediation and phytoremediation processes in environments contaminated by potentially toxic metals due to its resistance to several metals and being able to act as a growth promoter in bioaccumulating plants
The association of microorganisms with hyperaccumulating plants of potentially toxic metals (PTM) to remove, transfer or stabilize these elements from the soil is a suitable tool for bioremediation processes in contaminated environments. The ability of microorganisms to resist these environments depends on biochemical factors, physiological adaptations and their genetic adaptation. Therefore, the objective of this work is to evaluate the isolation capacity of Rhizobium sp. LBMP-C04 to be used for bioremediation and plant growth promotion in metal contaminated soils. For this purpose, in this work a prediction of genes related to PTM metabolism, growth promotion genes and antimicrobial resistance genes was performed, as well as the performance of biochemical tests to prove these characteristics in vitro of the bacterium Rhizobium sp. LBMP-C04. Through the linked annotations of the sequenced genome, it was possible to predict a variety of genes related to PTM resistance, plant growth promotion and antimicrobial resistance in the bacterial genome. Resistance genes are mainly associated with components related to efflux pumps, repair of DNA damage and the import or export of metal in bacterial cells, in order to maintain cell homeostasis. Genes that promote plant growth are related to mechanisms of osmotic stress tolerance, phosphate solubilization, nitrogen metabolism, biological nitrogen correction, biofilm formation, heat shock responses and indole-3-acetic acid biosynthesis (IAA), tryptophan and organic acids. The biochemical results indicate that the isolate Rhizobium sp. LBMP-C04 is able to solubilize calcium phosphate, produce siderophores and indole compounds in vitro; o was an isolate resistant to the antibiotics ampicillin, amoxicillin, rifampicin, nalidixic acid and trimethoppine. The isolate Rhizobium sp. LBMP-C04 presented MIC of 5, 14, 13, 12, 48 and 401 mmol dm-3 respectively to the metals Cd2+, Cu2+, Cr6+, Cr3+, Zn2 , and Ni2+, in addition to having detected intracellular accumulation of these, demonstrated by metal metals metals in the culture medium and by transmission electron microscopy. The observed results indicate the possibility of using the isolate Rhizobium sp. LBMP-C04 as an efficient bacterium in bioremediation and phytoremediation processes in environments contaminated by potentially toxic metals due to its resistance to several metals and being able to act as a growth promoter in bioaccumulating plants
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Palavras-chave
Biorremediação, Fitorremediação, Metais pesados, Genes