Further Evidence that the N(inf2)-Fixing Endophytic Bacterium from the Intercellular Spaces of Sugarcane Stems Is Acetobacter diazotrophicus (original) (raw)
Related papers
International Journal of Systematic Bacteriology, 1989
Results of deoxyribonucleic acid (DNA)-ribosomal ribonucleic acid and DNA-DNA hybridizations, together with a phenotypic and chemotaxonomic analysis, revealed that nitrogen-fixing bacteria isolated from roots and stems of sugarcane belong to a new species in the genus Acetobacter, for which the name Acetobacter diazotrophicus sp. nov. is proposed. Strain LMG 7603 (= Dobereiner PA1 5 = ATCC 49037) is the type strain. New microaerobic, gram-negative, N,-fixing bacteria were isolated from roots and stems of sugarcane in Brazil (1). Because of their ability to grow at low pH values and their ability to form acetic acid from ethanol, these organisms could belong to the acetic acid bacteria (the genera
Infection of sugar cane by the nitrogen-fixing bacterium Acetobacter diazotrophicus
Journal of Experimental Botany, 1994
Acetobacter diazotrophicus, an acid-tolerant endophytic bacterium which grows best on a sucrose-rich medium. In a series of experiments, aseptically-grown sugar cane plantlets were rooted in a liquid medium and inoculated with A. diazotrophicus originally isolated from field-grown sugar cane. After 4, 7, 9, and 15 d, plants were examined under light, scanning and transmission electron microscopes and the presence of A. diazotrophicus on and within plant tissues was confirmed by immunogold labelling. By 15 d, external bacterial colonization was seen on roots and lower stems, particularly at cavities in lateral root junctions. The loose cells of the root cap at root tips were a site of entry of the bacteria into root tissues. Both at lateral root junctions and root tips, bacteria were also seen in enlarged, apparently intact, epidermal cells. After 15 d, bacteria were present in xylem vessels at the base of the stem, many connected via mucus to spiral secondary thickening. There was no obvious pathogenic reaction to the bacteria within the xylem. From these observations, it is proposed that, under experimental conditions, A. diazotrophicus firstly colonized the root and lower stem epidermal surfaces and then used root tips and lateral root junctions to enter the sugar cane plant where it was distributed around the plant in the transpiration stream. It is further suggested that the xylem vessels in the dense shoots of mature plants are also a possible site of N 2 -fixation by diazotrophs as they provide the low pO 2 and energy as sucrose necessary for nitrogenase activity.
Twelve bacterial strains were isolated from root and rhizosphere samples collected from different sugarcane growing areas. Of these strains, ten strains were identified as Pseudomonas and two as Azotobacter on the basis of colony-and cell-morphology. Among isolates the presence of nifH gene was detected only in two Azotobacter strains (Azoto1 and Azoto2). Acetylene reduction activity of the strains Azoto1 and Azoto2 determined in N-free medium was 1966 and 4210 nmole C H /vial/24h, respectively. All isolates showed IAA 2 4 production in growth medium containing tryptophane as a precursor. Maximum IAA production (4.49mg/L) was detected in isolate A17 where as IAA production in strains A4 and A11 was also significant. Values for IAA production by nitrogen fixing isolates Azoto1 and Azoto2 were comparatively low (0.2 and 0.1mg/L respectively). For rapid screening of bacterial isolates from sugarcane, heterologous plant host (sorghum) was used as a test plant. Most of the strains showed beneficial effects on root length, root area and plant dry weight which were comparable to those observed in treatments where confirmed PGPR were used as positive control. Beneficial effects of inoculation on sugarcane grown in pots were also observed.
Plant and Soil, 1993
Thirteen cane cultivars grown on fields in México were sampled to assess the occurrence of Acetobacter diazotrophicus, a recently identified N2-fixing bacterium. Results showed that the isolation frequencies extended over a broad range (1.1 to 67%), likely to be related to the nitrogen fertilization level. The lowest isolation frequencies (1.1 to 2.5%) were obtained from plants growing at high nitrogen doses (275–300 kg ha-1) and the highest values (10–67%) from plants cultivated with 120 kg N ha-1. All eighteen strains of A. diazotrophicus produced indoleacetic acid (IAA) in defined culture medium. Estimates obtained from HPLC analyses revealed that A. diazotrophicus strains produced from 0.14 to 2.42 μg IAA mL-1 in culture medium. Considering that A. diazotrophicus is found within the plant tissue, the biosynthesis of IAA suggests that the bacteria could promote rooting and improve sugarcane growth by direct effects on metabolic processes, in addition to their role in N2 fixation.
Colonization of sugarcane by Acetobacter diazotrophicus is inhibited by high N-fertilization
FEMS Microbiology Ecology, 1999
Acetobacter diazotrophicus is a nitrogen-fixing endophytic bacterium, originally isolated from sugarcane. Its colonizing ability was evaluated in high and low N-fertilized sugarcane plants by inoculating stem-cuts with a L-glucuronidase marked A. diazotrophicus strain. Bacterial quantification by the most probable number technique showed a severe decrease of A. diazotrophicus cells in plants fertilized with high levels of nitrogen. The inoculated strain was detected inside low N-fertilized sugarcane plants by histochemical staining of L-glucuronidase and scanning electron microscopy. A. diazotrophicus was found mainly inside cortical cells of stems and inside xylem vessels. No L-glucuronidase activity was observed in non-inoculated plants. High nitrogen fertilization of fields might be a threat to maintaining naturally occurring endophytic associations.
Plant and Soil, 1993
Thirteen cane cultivars grown on fields in M6xico were sampled to assess the occurrence of Acetobacter diazotrophicus, a recently identified N2-fixing bacterium. Results showed that the isolation frequencies extended over a broad range (1.1 to 67%), likely to be related to the nitrogen fertilization level. The lowest isolation frequencies (1.1 to 2.5%) were obtained from plants growing at high nitrogen doses (275-300 kg ha -~) and the highest values (10-67%) from plants cultivated with 120 kg N ha -~. All eighteen strains of A. diazotrophicus produced indoleacetic acid (IAA) in defined culture medium. Estimates obtained from HPLC analyses revealed that A. diazotrophicus strains produced from 0.14 to 2.42/xg IAA mL J in culture medium. Considering that A. diazotrophicus is found within the plant tissue, the biosynthesis of IAA suggests that the bacteria could promote rooting and improve sugarcane growth by direct effects on metabolic processes, in addition to their role in N, fixation.
Anais da Academia Brasileira de Ciências
The growing need for the use of clean energy has led society to seek alternatives to fossil fuels in order to less pollute the environment. Sugarcane has been known to produce enough biomass and to have associative microorganisms, such as plant growth-promoting bacteria (PgPB), which have the potential to improve the yield of crops. The objective of this study is to evaluate the efficiency and the isotopic dilution of 15 N of microbial inoculants containing endophytic diazotrophic bacteria, individually inoculated and in mixture, on productivity, technological quality and biological nitrogen fixation (BNF) of sugarcane variety RB92579. The experiment was conducted for three consecutive years, comprising different crop cycles, in a completely randomized block design with four replications. The evaluations were at 11 months after planting for plant-cane, and at 12 months after cutting for ratoon cane and second ratoon cane. The contribution of BNF by 15 N natural abundance technique to inoculated treatments ranged from 18% to 57.31%. This study showed that no strain promoted the improvement on yield and biological nitrogen fixation during the three cycles of sugarcane (plant-cane, ratoon cane and second ratoon cane). However, industrial characteristics of sugar cane can be affectd by PGPB inoculation.
Plant and Soil, 2012
Background and aims Rhizospheric, epiphytic and endophytic bacteria are associated with several nonlegumes, colonizing their surface and inner tissues. Many of these bacteria are beneficial to their hosts, phomonas, Xanthomonas, Acinetobacter, Rhanella, Enterobacter, Pantoea, Shinella, Agrobacterium and Achromobacter. Additionally, some PGP features were studied in 35 selected isolates. The data obtained in this study represent the initial steps in a program Plant Soil (2012) 356:35-49 aimed at determining the mechanisms of PGP of nonlegume crops in Uruguay (such as sugarcane) with potentially beneficial plant-associated bacteria. Keywords Saccharum officinarum . Endophytes . Diazotrophs . PGPR . 15 N-isotope dilution Abbreviations BNF Biological nitrogen fixation IAA indole-3-acetic acid PGPE plant growth promoting endophytes % 15 N a.e atom % 15 N excess 15 N % Ndfa percent nitrogen derived from air
IOP Conf. Series: Earth and Environmental Science, 2021
The present review was focused on the isolation and nitrogen-fixing efficiency of Gluconacetobacter diazotrophicus associated with sugarcane crop. Gluconacetobacter diazotrophicus has a long-standing partnership with the bacterium Escherichia coli as an entophyte, which can efficiently fix atmospheric nitrogen. It plays a significant role and occurs in most sugarcane growing countries. It has been found to reside in the sugar cane root, stem, buds and leaves. Biological nitrogen fixation based farming systems would enhance agricultural production in the long term in both economically viable and socially acceptable way. This process not only replaces the most expensive fertilizer but also reduces considerably groundwater pollution with nitrates because biological nitrogen fixation was self-regulated. Convincing evidence has pointed out that biological nitrogen fixation requiring a relatively simple and low-cost technology, easy to execute and largely renewable sources of energy has a tremendous role to play in the immediate further of agriculture, especially in the developing and underdeveloped countries.