Estudo da variabilidade de bactérias promotoras de crescimento de plantas da espécie Bacillus subtilis
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2021-02-01
Autores
Santos, Bianca de Melo Silveira dos
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Universidade Estadual Paulista (Unesp)
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A utilização contínua de fertilizantes minerais na agricultura promove o excesso de nutrientes no solo, tais como nitrogênio, potássio e fósforo, podendo causar alterações na microbiota do solo, promovendo danos. Em geral, as plantas possuem baixa eficiência em absorver tais nutrientes, o que leva a uma baixa eficiência na utilização da adubação mineral. A utilização de bactérias promotoras de crescimento de plantas tem sido uma promissora alternativa na busca de melhorar a eficiência na utilização de insumos agrícolas, podendo trazer inúmeros benefícios para a agricultura. Porém, bactérias da mesma espécie podem promover diferentes níveis de crescimento. O presente estudo teve por objetivo avaliar a ação de oito isolados de Bacillus subtilis quanto à promoção do crescimento de plantas na cultura do milho em condições de casa de vegetação, assim como sua atividade metabólica, capacidade de degradação enzimática, produção de sideróforos, tolerância aos íons Cd(II), Cr(III), Ni(II), Zn(II), Cu(II) e Cr(VI) e antagonismo de agentes fitopatogênicos. O experimento foi conduzido em casa de vegetação, constituído por nove tratamentos – oito isolados de B. subtilis e um controle, em delineamento utilizado foi o casualizado com cinco repetições. A atividade metabólica foi avaliada pelo consumo de diferentes fontes de carbono utilizando placas EcoPlate. A capacidade de degradação enzimática, produção de sideróforos, tolerância a Cd(II), Cr(III), Ni(II), Zn(II), Cu(II) e Cr(VI) e antagonismo foi verificada utilizando meio de cultura (caldo nutriente) em placas. O isolado 290 promoveu maior crescimento de plantas, e foi o único capaz de consumir ácido glicil – L – glutâmico. Todos os isolados foram capazes de produzir amilase, celulase, e solubilizar fosfato orgânico. Os isolados foram mais resistentes ao Zn(II) e Cr(III). O antagonismo contra agentes fitopatogênicos foi verificado para os fungos: Alternaria alternata, apenas 290 apresentou ausência de antagonismo; Colletotrichum gloeosporioides apenas os isolados 248, 291, e 287 foram antagônicos; Phyllosticta citricarpa todos os isolados foram antagônicos, e apenas 290 apresentou um fraco antagonismo; e para o Geotrichum citri-aurantii apenas os isolados 309 e 287 foram antagônicos. Seis isolados foram capazes de produzir sideróforos, exceto o isolado 290 e 291. O presente estudo avaliou o comportamento de oito isolados de Bacillus subtilis perante a promoção de crescimento de plantas relacionando com suas características genéticas e fisiológicas. Estes resultados abrem caminho para novos estudos na tentativa de esclarecer quais são os mecanismos de ação de cada isolado, e quais fatores genéticos podem interferir em suas atividades a fim de promover o crescimento vegetal de maneira mais efetiva. Os resultados também mostram a possibilidade da utilização desses isolados para produção de enzimas de interesse biotecnológico, biorremediação áreas contaminadas e promoção de ações antagônicas contra agentes fitopatogênicos.
The continuous use of mineral fertilizers in agriculture promotes the excess of nutrients in the soil, such as nitrogen, potassium and phosphorus, which can cause changes in the soil's microbiota, promoting damage. In general, plants have low efficiency in absorbing such nutrients, which leads to low efficiency to utilize the mineral fertilization. The use of plant growthpromoting bacteria has been a promising alternative to improve the efficiency in the use of agricultural inputs, and can be an effective strategy for agriculture. However, bacteria of the same species can promote plant growth differently. The present study aimed to evaluate the action of eight isolates of B. subtilis regarding the promotion of plant growth in maize culture in a greenhouse conditions, as well as their metabolic activity, enzymatic degradation capacity, production of siderophores, tolerance ions Cd (II), Cr (III), Ni (II), Zn (II), Cu (II) and Cr (VI) and antagonism of phytopathogenic agents. The experiment was conducted in a greenhouse, consisting of nine treatments - eight isolates of B. subtilis and one control, in a randomized design with five replications. Metabolic activity was assessed by consuming carbon sources using EcoPlate plates. The capacity of enzymatic degradation, production of siderophores, tolerance to Cd (II), Cr (III), Ni (II), Zn (II), Cu (II) and Cr (VI) and antagonism was verified using culture medium (nutrient broth) in plates. Isolate 290 promoted greater plant growth, and was the only one capable of consuming glycyl - L - glutamic acid. All isolates were able to produce amylase, cellulase, and solubilize organic phosphate. The isolates were more resistant to Zn (II) and Cr (III). Antagonism against phytopathogenic agents was found for fungi: Alternaria alternata, only 290 showed no antagonism; to Colletotrichum gloeosporioides only isolates 248, 291, and 287 were antagonistic; Phyllosticta citricarpa, all isolates were antagonistic, and only 290 showed weak antagonism; and Geotrichum citriaurantii, only isolates 309 and 287 were antagonistic. Six isolates were able to produce siderophores, except isolate 290 and 291. The present study evaluated the behavior of eight isolates of Bacillus subitilis towards the promotion of plant growth relating to their genetic and physiological skills. These results open the way for further studies in an attempt to clarify which are the mechanisms of action of each isolate, and which genetic factors can interfere in its activities in order to promote plant growth in a more effective wa. These results also have shown the possibility to use these isolates to enzymes production of biotechnological interest, bioremediation of contaminated areas and promote antagonistic actions against phytopathogenic agents,
The continuous use of mineral fertilizers in agriculture promotes the excess of nutrients in the soil, such as nitrogen, potassium and phosphorus, which can cause changes in the soil's microbiota, promoting damage. In general, plants have low efficiency in absorbing such nutrients, which leads to low efficiency to utilize the mineral fertilization. The use of plant growthpromoting bacteria has been a promising alternative to improve the efficiency in the use of agricultural inputs, and can be an effective strategy for agriculture. However, bacteria of the same species can promote plant growth differently. The present study aimed to evaluate the action of eight isolates of B. subtilis regarding the promotion of plant growth in maize culture in a greenhouse conditions, as well as their metabolic activity, enzymatic degradation capacity, production of siderophores, tolerance ions Cd (II), Cr (III), Ni (II), Zn (II), Cu (II) and Cr (VI) and antagonism of phytopathogenic agents. The experiment was conducted in a greenhouse, consisting of nine treatments - eight isolates of B. subtilis and one control, in a randomized design with five replications. Metabolic activity was assessed by consuming carbon sources using EcoPlate plates. The capacity of enzymatic degradation, production of siderophores, tolerance to Cd (II), Cr (III), Ni (II), Zn (II), Cu (II) and Cr (VI) and antagonism was verified using culture medium (nutrient broth) in plates. Isolate 290 promoted greater plant growth, and was the only one capable of consuming glycyl - L - glutamic acid. All isolates were able to produce amylase, cellulase, and solubilize organic phosphate. The isolates were more resistant to Zn (II) and Cr (III). Antagonism against phytopathogenic agents was found for fungi: Alternaria alternata, only 290 showed no antagonism; to Colletotrichum gloeosporioides only isolates 248, 291, and 287 were antagonistic; Phyllosticta citricarpa, all isolates were antagonistic, and only 290 showed weak antagonism; and Geotrichum citriaurantii, only isolates 309 and 287 were antagonistic. Six isolates were able to produce siderophores, except isolate 290 and 291. The present study evaluated the behavior of eight isolates of Bacillus subitilis towards the promotion of plant growth relating to their genetic and physiological skills. These results open the way for further studies in an attempt to clarify which are the mechanisms of action of each isolate, and which genetic factors can interfere in its activities in order to promote plant growth in a more effective wa. These results also have shown the possibility to use these isolates to enzymes production of biotechnological interest, bioremediation of contaminated areas and promote antagonistic actions against phytopathogenic agents,
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Sideróforos, Antagonismo, Metais pesados, Ecoplate, Zea mays