Characterization and activity of endophytic bacteria from ‘Prata Anã’ banana crop (Musa sp., AAB)

Abstract

The objective of this study was to characterize banana tree endophytic bacteria at genus and species level and to determine the metabolic reactions associated with the nitrogen transformations. The identification at genus and species levels was performed using the partial sequencing of the rDNA 16S region. The assimbyotic nitrogen fixation, the reduction of nitrate and the production of urease were in vitro evaluated. The DNA of the bacterial isolates was also amplified to verify the presence of the nifH, nirK and nirS regions. Biochemical tests were performed in a complete randomized design; the treatments consisted of 39 bacterial isolates with three replications. Sequence analysis enabled the identification of four genera: Bacillus, Rhizobium, Klebsiella and Enterobacter. The Bacillus genus occurred more frequently, nine species were identified. By evaluating the results of biochemical tests, it was observed that three isolates showed multiple abilities: growth in NFb medium, nitrate reduction and production of urease. The isolates belong to the genus Bacillus and of the species subtilis, thuringienses and amyloliquefaciens. Approximately 12.5% of the isolates amplified the region corresponding to the nifH gene, 7.5% amplified gene nirK and 3.9% amplified the nirS gene. Endophytic bacteria evaluated in the present study showed in vitro activity for urease, nitrate reductase enzymes, however, relevant nitrogenase activity was not observed.

Probiotic Endophytes for More Sustainable Banana Production

“…Pereira et al [ 86 ], from the same research group in Brazil, characterized 39 bacterial isolates from roots and grouped them into 4 genera: Bacillus , Rhizobium , Klebsiella, and Enterobacter . The genus Bacillus occurred more frequently (92.5%) than the other genera, which only contained one representative of each genus (2–5%).…”

“…Nitrate reductase catalyzes the first step in the reduction of nitrate to ammonium for the N-organic synthesis. In addition, only 30% of the isolates were verified as urease positive, including Bacillus , Klebsiella and Enterobacter [ 86 ]. It is well-known that urease catalyzes the hydrolysis of urea to ammonium and CO 2 .…”

“…Both studies showed that Proteobacteria is the main microbial phylum in Cavendish bananas. The averages were calculated using data from previously published studies [ 33 , 81 , 84 , 85 , 86 , 87 , 88 ].…”

Autochthonous endophytic bacteria from Musa sp. controls Fusarium oxysporum f. sp. cubense under in vitro conditions

“…However, several research studies have shown that the banana microbiome is quite diverse and rich in bacterial species (Souza et al 2013, Pereira et al 2018.…”