Colonization and growth promotion characteristics ofEnterobactersp. andHerbaspirillumsp. onBrassica oleracea

Abstract

We investigated the effects of inoculating a dicot plant, Brassica oleracea, with nitrogen-fixing endophytic bacteria isolated from monocots. The bacteria used were Enterobacter sp. strain 35 isolated from sugarcane and Herbaspirillum sp. strain B501 isolated from wild rice. Under glasshouse conditions, B. oleracea inoculated with strain 35 had a significantly greater fresh weight than uninoculated plants, and the fresh weight of plants inoculated with strain B501 tended to be higher than that of uninoculated plants. We conducted a laboratory-scale experiment to confirm the above results and to investigate the colonization and nitrogen-fixing abilities of these bacteria. Plants inoculated with Enterobacter sp. strain 35-1, a green fluorescent protein (GFP)-labeled strain derived from strain 35, had larger bacterial populations and greater acetylene reduction activity than those inoculated with Herbaspirillum sp. strain B501gfp1. Strain 35-1 colonized the intercellular spaces and the junctions of the lateral roots with the parent root. The results indicated that isolates from monocots can successfully colonize B. oleracea (a dicot) and promote plant growth.

Some Characteristics of a Plant Growth Promoting <i>Enterobacter</i> sp. Isolated from the Roots of Maize

“…As has been variously reported [21,22], Enterobacter sp.-NCOO1927-MR5 was shown in this study to tolerate 3% NaCl as well as resist inhibition by the antibiotic, streptomycin. The production of ammonia is frequently reported for PGPR, a process most probably resulting from the deamination (ammonification) of the amino acids present in the peptone used for this assay.…”

“…However, the majority of strains reported recently has been isolated from environmental sources and have been studied for their various beneficial activities. Such activities include the promotion of plant growth [21,25,26], biocontrol of plant diseases [22,23] and even the conversion of carbohydrate compounds in acid hydrolysates of hemicellulose into ethanol and other fermentation products [15]. These reports have raised the profile of E. asburiae as an industrial microorganism.…”

“…Lack of host specificity is a good attribute for microbial inocula, which may thus be used for the cultivation of a wide range of crops. Zakria et al [21] earlier reported that Enterobacter sp. strain 35 isolated from sugarcane successfully colonized and promoted growth of Brassica oleracea (broccoli), a dicot.…”

“…In field experiments, this species was reported to have also, significantly improved total kernel biomass. Zakria et al [21], have shown that under glasshouse conditions, Brassica oleracea (broccoli), a dicot plant inoculated with Enterobacter sp. strain 35 had a significantly greater fresh weight than uninoculated plants.…”

Survival Strategies of the Plant-Associated Bacterium Enterobacter sp. Strain EG16 under Cadmium Stress

“…Bacteria belonging to the genus Enterobacter have been found to associate frequently with a large number of plant species, colonizing the rhizosphere and other plant parts (63)(64)(65)(66). Moreover, several metal-resistant Enterobacter species, including some with PGP effects, have been isolated, and some of their characteristics in response to metals have been determined (67)(68)(69)(70)(71)(72).…”