Bioprospecção de isolados de Bacillus promotores de crescimento de milho cultivado em solo autoclavado e natural

Abstract

RESUMOObjetivou-se, neste trabalho, selecionar isolados bacterianos do gênero Bacillus em amostras de solo da região oeste paulista e avaliar o efeito de sua inoculação em milho cultivado em duas condições de solo (natural e autoclavado). Trinta e oito isolados bacterianos, caracterizados como Bacillus sp. foram avaliados previamente quanto ao antagonismo a fungos fitopatogênicos e produção de hormônio vegetal (auxinas) em laboratório. Foram selecionados 14 isolados para inoculação de milho cultivado em vasos, em casa de vegetação durante 50 dias. As avaliações efetuadas durante a condução do experimento foram: altura de plantas; número de folhas desdobradas e biomassa seca produzida aos 50 dias após a semeadura. O cultivo do milho em solo autoclavado proporcionou maior número de folhas desdobradas e produção de biomassa na planta. Os isolados bacterianos BRG-2, CAS-2, NGR-1, PNP-2, PRP-2 e TAC-2, destacaram-se como promotores de crescimento do milho, avaliado pela produção de biomassa pela planta aos 50 dias de idade. Dos oito antagonistas avaliados apenas quatro foram promotores de crescimento do milho. A maior produção de AIA não foi uma característica principal dos melhores isolados bacterianos que promoveram o crescimento do milho.Termos para indexação: Rizobactérias, auxinas, controle biológico, Zea mays. ABSTRACTThe objective of this work was to select bacterial isolates of the genus Bacillus in soil samples of West of the State of São Paulo and to assess the effect of their inoculation in corn growing in two soil conditions (natural and sterilized). 38 bacterial isolates characterized as belonging to the Bacillus genus were previously evaluated regarding their antagonism to phytopathogenic fungi and their production of plant hormones (auxines) in the laboratory. The corn plants were inoculated with 14 Bacillus isolates and grown in in a greenhouse for 50 days. The evaluations made during the conduction of the trial were: plant height, number of leaves and biomass dry weight. The bacterial isolates BRG-2, CAS-2, NGR-1, PNP-2, PRP-2 and TAC-2 were able to promote maize growth. Among the best isolates four were antagonist to phytopathogenic fungi. The AIA production was not the main feature of the best bacterial isolates that promoted the growth of corn.

Bioprospecção de rizobactérias promotoras de crescimento em Brachiaria brizantha

“…Este resultado comprova o potencial de promoção de crescimento de plantas por Bacillus sp. já encontrado em vários estudos com diferentes culturas (Araujo & Guerreiro, 2010;Figueiredo et al, 2010;Araujo, 2008;Coelho et al, 2007;Malik et al, 1997).…”

Identification and characterization of endophytic bacteria from corn (Zea mays L.) roots with biotechnological potential in agriculture

“…For example, Sarwar and Kremer ([1995]), by comparing the production of auxin between promoting and inhibiting bacteria growth, noted that the latter produced high levels and inhibited root growth of Convolvulus arvensis ; Baranzani and Friedman ([1999]) observed the same effect with lettuce ( Lactuca sativa L.). Araujo and Guerreiro ([2010]), working with Bacillus , found that most strains of corn identified as growth promoters did not correspond to those producing higher levels of IAA. The species Pseudomonas fluorescens , whose production of IAA was only 15.63 μg/mL, increased root length in corn plants, according to Hernández-Rodríguez et al ([2008]).…”

“…CNPSo 2477 and CNPSo 2476 were the most efficient in the inhibition against all four fungi tested. They are known to have an antagonist effect against various fungi, for example, F. moniliforme, F. graminearum, M. phaseolina (Pal et al [ 2001 ]), F. oxysporum and Colletotrichum truncatum (Araujo and Guerreiro [ 2010 ]). One of the advantages of the biological control strategy using endophytic bacteria is that they can act in the same niche, in direct competition with the pathogens (Bacon and Hinton, [ 2002 ]).…”

Promotion of maize growth using endophytic bacteria under greenhouse and field conditions

“…Furthermore they have indirect benefits to plant development, such as biocontrol and disturbing quorum sensing (Bhattacharyy and Jha, 2012) Among PGPR, the genus Bacillus is comprises diverse species of rhizospheric and endophytic bacteria with the ability to synthesize phytohormones that can favor root growth by increasing root hair (Angulo et al, 2014). Moreover, their application to maize can contribute to plant growth, development and nutrition (Araujo and Guerreiro, 2010;Lin et al, 2018). Bacillus spp.…”