Phylogenetic diversity of thermophilic carbohydrate degrading bacilli from Bulgarian hot springs

Phylogenetic diversity of culturable bacteria from genus Bacillus and related genera, isolated from 18 Bulgarian hot springs was investigated in association with their functional diversity. Sixty-seven thermophilic and facultative thermophilic strains were isolated under aerobic conditions at 60°C. Sixty-six of them belonged to eight species in four genera from Bacillus group: Anoxybacillus, Geobacillus, Brevibacillus and Bacillus. Representatives of the genus Anoxybacillus predominated. Based on phylogenetic analysis (<97% sequence similarity) four strains belonged to groups representing potentially novel species. Producers of carbohydrases, degrading 12 from the tested 13 substrates were isolated. About half of the isolates degraded amylose by exo- or endo-mechanism of action of their enzymes. The isolates degrading hemicellulose carbohydrates like arabinan, arabinoxylan, β-glucan, galactan, galactomannan and xyloglucan were reached to. Some of the microorganisms were able to uptake microbial polysaccharides like curdlan and gellan and their enzymes were between first reported thermostable enzymes in their groups, like gellan lyase and curdlan lyase A relation between species affiliation and their functional activity was observed—all A. gonensis strains were producer of amylolytic enzymes, most of Brevibacillus ruber strains were able to grow in a minimal medium with xanthan.     

Isolation and characterisation of phosphate solubilising microorganisms from the cold desert habitat of <Emphasis Type="Italic">Salix alba Linn.</Emphasis> in trans Himalayan region of Himachal Pradesh

Phosphate solubilising microorganisms (PSM) (bacteria and fungi) associated with Salix alba Linn. from Lahaul and Spiti valleys of Himachal Pradesh were isolated on Pikovskaya (PVK), modified Pikovskaya (MPVK) and National Botanical Research Institute agar (NBRIP) media by spread plating. The viable colony count of P-solubilising bacteria (PSB) and fungi (PSF) was higher in rhizosphere than that of non-rhizosphere. The frequency of PSM was highest on MPVK followed by NBRIP and PVK agar. The maximum proportion of PSM out of total bacterial and fungal count was found in upper Keylong while the least in Rong Tong. The PSB frequently were Gram-positive, endosporeforming, motile rods and belonged to Bacillus sp. The PSF mainly belonged to Penicillium sp., Aspergillus fumigatus, A. niger, A. spp. and non-sporulating sterile. Amongst the isolates with high efficiency for tricalcium phosphate (TCP) solubilisation, seven bacterial and seven fungal isolates dissolved higher amount of P from North Carolina rock phosphate (NCRP) than Mussoorie rock phosphate (MRP) and Udaipur rock phosphate (URP). However, the organisms solubilised higher-P in NBRIP broth than PVK broth. SBC5 (Bacillus sp.) and SBC7 (Bacillus sp.) bacterial isolates exhibited maximun P solubilisation (40 and 33 μg ml⁻¹ respectively) whereas FC28 (Penicillium sp.) isolate (52.3 μg ml⁻¹) amongst fungi while solubilising URP. The amount of P solubilised was positively correlated with the decrease in pH of medium. SBC5 (Bacillus sp.), SBC7 (Bacillus sp.) and SBC4 (Micrococcus) decreased the pH of medium from 6.8 to 6.08 while FC28 (Penicillium sp.) and FC39 (Penicillium sp.) isolates of fungi recorded maximum decrease in pH of medium from 6.8 to 5.96 in NBRIP broth.     

Diazotrophic bacilli isolated from the sunflower rhizosphere and the potential of Bacillus mycoides B38V as biofertiliser

The nitrogen fixation by strains belonging to the Bacillus genus remains poorly explored. In this work, the diversity of endospore‐forming bacilli isolated from the rhizosphere of sunflower was evaluated. A total of 101 strains were identified based on the V1‐V2 variable regions of the 16S rRNA gene. Strains belonging to the genera Bacillus and Paenibacillus represented 41.6% and 58.4%, respectively, of total isolates. The production of indolic compounds was a common trait among the isolates, and approximately 75% of them exhibited positive nitrogenase activity; but only 9.2% displayed activities higher than 1 nmol C₂H₄ mg protein h^?1. Within the genus Bacillus, the isolates related to the B. cereus group displayed the highest nitrogenase activity and were the second most frequent group of Bacillus sp. isolated. Plants inoculated with the isolate B38V showed the highest N content, and their shoot dry weights were significantly increased compared with positive control. Our results indicated that B38V, which belongs to the B. mycoides species, has the potential to promote sunflower growth. The data obtained in this study provide additional information concerning the diversity of Gram‐positive diazotrophic within the genera Bacillus and Paenibacillus and their potential for the biofertilisation of sunflower crops.     

Evaluation of diversity of Bacilli from chickpea rhizosphere by 16S ARDRA and assessment of their plant-growth-promoting attributes

A total of eight motile, aerobic, Gram-positive and straight rod-shaped, endospore forming Bacillus spp. were isolated from rhizosphere of chickpea plants collected from different agricultural fields. Phylogeny of isolates was studied by partial sequencing of 16S rDNA and comparative analysis of the sequence data confirmed that the isolates belong to distinct phylogenetic lineage corresponding to Bacillus. Phenotyping clusters correlate with ARDRA pattern and showed resemblance to partial 16S rDNA sequencing. Bacillus spp. BSK5 and Bacillus subtilis BSK17 were the most potent strains for having plant-growth-promoting attributes. These two strains solubilised inorganic phosphate, produced Indole acetic acid, siderophore, Hydrocyanic acid and secreted extracellular chitinase and mild β-1,3-glucanase which antagonised and caused mycelial deformities in two phytopathogens Macrophomina phaseolina and Fusarium oxysporum in dual culture and by culture filtrate.     

Screening for PGPR to improve growth of Cistus ladanifer seedlings for reforestation of degraded mediterranean ecosystems

A screening for PGPRs was carried out in the rhizosphere of wild populations of Cistus ladanifer. Two hundred and seventy bacteria were isolated, purified and grouped by morphological criteria. Fifty percent of the isolates were selected and tested for aminocyclopropanecarboxylic acid (ACC) degradation, auxin and siderophore production and phosphate solubilisation. Fifty-eight percent of the isolates showed at least one of the evaluated activities, with phosphate solubilisation and siderophore production being the most abundant traits. After PCR-RAPDs (Randomly amplified polymorphic DNA) analysis, 11 groups appeared with 85% similiarity, revealing the low diversity in the system. One strain of each group was tested in a biological assay, and those that enhanced Cistus growth were identified by 16S rDNA sequencing.Although seven of the 11 assayed strains were phosphate solubilisers and able to produce siderophores, only one was really effective in increasing all biometric parameters in Cistus ladanifer seedlings, the lack of effect of the other six probably being due to the rich substrate used. This suggests that other mechanisms apart from nutrient mobilisation might be involved in growth promotion by this strain. However, the low diversity together with the high redundancy detected by PCR-RAPDs and the predominance of strains able to mobilise nutrients in the rhizosphere of Cistus reveals that the plant selects for bacteria that can help to supply scarce nutrients. This type of plant growth promoting rhizobacteria (PGPR) strains should be succesful in reforestation practices.     

Suppression of red rot caused by <Emphasis Type="Italic">Colletotrichum falcatum</Emphasis> on sugarcane plants using plant growth-promoting rhizobacteria

Bacterial strains with ability to suppress Colletotrichum falcatum were isolated from the rhizosphere of sugarcane. Thirty nine candidates, chosen on the basis of in vitro antagonism, inhibited C. falcatum growth by 15–65% on test plates. Twenty two isolates causing 50% or more in vitro inhibition were screened for their root colonization ability and biocontrol activity on micropropagated sugarcane plants under greenhouse conditions. Twelve strains suppressed red rot infection in plantlets, but no significant correlation was observed between in vitro pathogen inhibition and in vivo disease suppression. However, isolates showing root colonization over 5.2 log₁₀ CFU g⁻¹ of soil showed highest suppression of C. falcatum and reduction of red rot disease. Six strains with the capability to maintain a significant population in the sugarcane rhizosphere and with a high potential to control red rot were identified by 16S rDNA as Ochrobacterum intermedium NH-5, Pseudomonas putida NH-50, Bacillus subtilis NH-100, Bacillus subtilis NH-160, Bacillus sp NH-217 and Stenotrophomonas maltophilia NH-300.     

Characterization and Phylogenetic Diversity of Carboxymethyl Cellulase Producing <Emphasis Type="Italic">Bacillus</Emphasis> Species from a Landfill Ecosystem

Total population of cellulose degrading bacteria was studied in a landfill ecosystem as a part of microbial diversity study. Samples were obtained from 3 and 5 feet depth of a local landfill being operated for past 10 years. Among many isolates, 22 bacterial strains were selected based on their capability to decompose carboxymethyl cellulose (CMC). These isolates were cultivated on agar medium with CMC as the carbon source. All isolates were Gram positive, endospore forming and alkalophilic bacteria with optimum growth pH 9–10. They were grouped based on the phenotypic and chemotaxonomic characters and representative strains of different groups along with high carboxymethyl cellulase (CMCase) producing strains were included for further characterization. Analysis of 16S rRNA gene indicated that these strains belong to different species of the genus Bacillus. Maximum CMCase activity of 4.8 U/ml at 50°C was obtained by strain LFC15. Results in the present study indicated the potential of waste land ecosystems such as landfill are potential source for isolation of industrially important microorganisms.     

烤烟根际烟碱降解细菌的多样性及其促生特性分析

【背景】挖掘兼具烟碱降解和植物根际促生细菌(Plant Growth-Promoting Rhizobacteria,PGPR)功能的细菌资源,有助于保护土壤质量,实现绿色种植。【目的】分析烤烟根际细菌多样性,筛选可降解高浓度烟碱的PGPR。【方法】采用纯培养法在选择性培养基上分离烟碱降解细菌。通过BOXA1R-PCR分析技术、16SrRNA基因测序及系统发育树构建,对菌株的遗传多样性和分类学地位进行分析。进一步评价了菌株的吲哚乙酸(Indole-3-Acetic Acid,IAA)活性、溶磷能力、病原菌拮抗能力等PGPR指标,以筛选出高效PGPR,最后通过盆栽试验验证其促生效果。【结果】分离得到58株烟碱降解细菌,根据BOXA1R-PCR指纹图谱选取11株菌进行16S rRNA基因序列测定,结果表明,58株菌分别属于芽孢杆菌属(Bacillus)、假单胞菌属(Pseudomonas)、拉乌尔菌属(Raoultella)和短波单胞菌属(Brevundimonas)4个属,以芽孢杆菌属(Bacillus)为优势菌属。58株细菌中48.28%的菌株可产IAA,27.59%具备溶磷能力,37.93%具备纤维素降解能力,G2-13、G2-3及HT2-8因促生与抗病特性突出而被筛选为目标功能菌。盆栽试验结果表明,G2-13菌株对幼苗生长的促进作用明显,可使株高与地上部鲜重分别增加33.05%与53.32%。【结论】烤烟根际存在较为丰富多样的烟碱降解细菌,它们在种植业上具有潜在的应用价值。     

Biocontrol Potential of Soybean Bacterial Endophytes Against Charcoal Rot Fungus, <Emphasis Type="Italic">Rhizoctonia bataticola</Emphasis>

A total of 137 bacterial isolates from surface sterilized root, stem, and nodule tissues of soybean were screened for their antifungal activity against major phytopathogens like Rhizoctonia bataticola, Macrophomina phaseolina, Fusarium udam, and Sclerotium rolfsii. Nine bacterial endophytes suppressed the pathogens under in vitro plate assay. These were characterized biochemically and identified at the genus level based on their partial sequence analysis of 16S rDNA. Eight of the isolates belonged to Bacillus and one to Paenibacillus. The phylogenetic relationship among the selected isolates was studied and phylogenetic trees were generated. The selected isolates were screened for biocontrol traits like production of hydrogen cyanide (HCN), siderophore, hydrolytic enzymes, antibiotics, and plant growth promoting traits like indole 3-acetic acid production, phosphate solubilization, and nitrogen fixation. A modified assessment scheme was used to select the most efficient biocontrol isolates Paenibacillus sp. HKA-15 (HKA-15) and Bacillus sp. HKA-121 (HKA-121) as potential candidates for charcoal rot biocontrol as well as soybean plant growth promotion.     

缓解花生连作障碍的根际促生菌分离及功能鉴定

【目的】长期连作障碍严重降低花生生产的产量及品质,根际促生菌可有效降解土壤中自毒化感物质、抑制植物病原菌生长及促进植物生长,从而有效缓解连作障碍问题。筛选优化具有缓解花生连作障碍能力的多功能根际益生微生物,验证其益生作用能力,为根际促生菌株在连作障碍中的应用提供理论依据及技术支持。【方法】采集连作12年地块花生根际土壤,利用以酚酸为唯一碳源的筛选培养基获得具有酚酸自毒化感物质降解及利用能力的根际促生菌,通过16S rRNA基因测序进行系统发育分析,确定根际促生菌菌株的分类地位,并验证其对植物病原菌生长抑制能力及解磷、解钾、产植物激素吲哚乙酸能力。【结果】从连作12年的花生发病土壤中获得7株可高效降解酚酸类自毒物质且降解底物多样的根际微生物菌株,经16S rRNA测序比对分别为克雷伯氏菌B02 (Klebsiella sp. B02)、克雷伯氏菌B07(Klebsiella sp. B07)、克雷伯氏菌B15 (Klebsiella sp. B15)、芽孢杆菌B28 (Bacillus sp. B28)、不动杆菌P09(Acinetobacter sp. P09)、布鲁氏杆菌VA05 (...     

Hippophae rhamnoides L. rhizobacteria exhibit diversified cellulase and pectinase activities

Hippophae rhamnoides L. provides an enormous range of medicinal and nutritional benefits. The significant abilities of this plant to survive in Himalayan high altitudes enticed our study to investigate its rhizosphere. Seventeen rhizobacterial strains were isolated from the rhizospheric soil and plant root nodules, belonging to genus Frankia, Azorhizobium, Bacillus, Paenibacillus, Brevibacillus and Pseudomonas, as identified by 16SrRNA sequencing. This varying bacterial population was further examined for the presence of root degrading enzymes pectinase and cellulase, which enable them to intrude the plant roots. Based on the growth and substrate utilization by these rhizobacteria on pectinase screening agar medium and Mandels and Reese agar medium, all the seventeen strains were identified as pectinase and cellulase producing rhizobacteria. The quantitative analysis by DNS method demonstrated varying enzyme activities, spot-lighting the physiological variation in the microbiome. The divergence in the enzyme activities shown by all the strains was analysed statistically, using the software ASSISTAT.

     

Assessment of functional and genetic diversity of aerobic endospore forming Bacilli from rhizospheric soil of Phyllanthus amarus L.

Fifty two aerobic and endospore forming Bacilli (AEFB) strains were recovered from rhizospheric soil of Phyllanthus amarus. Morphological, biochemical and molecular characterization by 16S rDNA gene sequencing has shown that these bacterial strains belong to six different genera of AEFB i.e. Bacillus, Brevibacillus, Lysinibacillus, Paenibacillus, Terribacillus and Jeotgalibacillus. Analysis of their PGP activities has shown that 92.30 % strains produced indole acetic acid hormone, 86.53 % of the strains solubilized Phosphate and 44.23 % strains produced siderophore. Chitinase production activity was shown by 42.30 % of the strains and 21.15 % of the strains produced 1-amino cyclopropane-1-carboxylate (ACC) deaminase. 46.15 % of isolates have shown antagonistic activity against common fungal pathogen of the plant i.e. Corynespora cassiicola. Among all of the isolated strains B. Cereus JP44SK22 and JP44SK42 have shown all of the six plant growth promoting traits tested. B. megaterium strains (JP44SK18 and JP44SK35), Lysinibacillus sphaericus strains (JP44SK3 and JP44SK4) and Brevibacillus laterosporus strain JP44SK51 have also shown multiple PGP activities except ACC deaminase production activity. In the present study bacterial strain belonging to genera Jeotgalibacillus sp. JP44SK37 has been reported first time as a member of rhizospheric soil habitat and has also shown PGP activities. It can be concluded that Rhizosphere of P. amarus has harboured a good diversity of AEFB bacterial strains having a lot of biofertilizing and biocontrol abilities.     

Isolation and characterization of rhizobacteria associated with coastal agricultural ecosystem of rhizosphere soils of cultivated vegetable crops

In this study, a total of 80 rhizobacteria was isolated from coastal agricultural ecosystem of cultivated vegetable rhizosphere soils. The isolates were screened for antagonistic activity against Sclerotium rolfsii and Colletotrichum capsici and plant growth promoting traits. The results revealed that 15.0 and 43.7% isolates showed statistically significant inhibition of mycelial growth of S. rolfsii and C. capsici respectively, while 48.7% isolates produced siderophore, 57.5% isolates solubilized phosphate and 21.1% isolates produced indole-3-acetic acid more than 20 μg/mL. However, only three isolates PfS1, PfR2 and BL5 were found positive to all properties tested. The identification of potential bacterial isolates through Microbial Identification System (BIOLOG) and 16S rDNA sequencing of the isolates revealed Bacillus species were dominant in the cultivated vegetable rhizosphere soil of Neil and Havelock Islands, India.     

Identification and characterization of chitinolytic bacteria isolated from a freshwater lake

To develop a novel type of biocontrol agent, we focus on bacteria that are characterized by both chitinase activity and biofilm development. Chitinolytic bacteria were isolated from sediments and chitin flakes immersed in the water of a sand dune lake, Sakata, in Niigata, Japan. Thirty-one isolates from more than 5100 isolated strains were examined chitinase activity and biofilm formation. Phylogenetic analysis of these isolates based on the 16S rRNA gene sequences revealed that most isolates belonged to the family Aeromonadaceae, followed by Paenibacillaceae, Enterobacteriaceae, and Neisseriaceae. The specific activity of chitinase of four selected strains was higher than that of a reference strain. The molecular size of one chitinase produced by Andreprevotia was greater than that of typical bacterial chitinases. The dialyzed culture supernatant containing chitinases of the four strains suppressed hyphal growth of Trichoderma reesei. These results indicate that these four strains are good candidates for biocontrol agents.     

Enhancement of Green Gram Nodulation and Growth by Bacillus Species

Rhizobacteria belonging to Bacillus sp. were isolated from the rhizosphere of green gram (Vigna radiata). Seed inoculation with the rhizobacteria showed stunting effect on root growth whereas four Bacillus strains caused stimulation of shoot growth at both 4 and 7 d of observations. Coinoculation of some Bacillus strains with effective Bradyrhizobium strain S24 resulted in enhanced nodulation and plant growth of green gram. The shoot dry mass (ratio to uninoculated control) varied from 1.32 to 6.33 at day 30 and from 1.28 to 3.55 at day 40 of plant growth. Nodule promoting effect after 40 d of plant growth was observed with majority of Bacillus strains except for MRS9 and MRS26. Maximum gains in nodulation, nitrogenase activity and plant growth were observed with Bacillus strains MRS12, MRS18, MRS22 and MRS27 after 40 d of plant growth, suggesting the usefulness of introduced rhizobacteria in improving crop productivity.     

<Emphasis Type="Italic">Paenibacillus pini</Emphasis> sp. nov., a cellulolytic bacterium isolated from the rhizosphere of pine tree

Strain S22^T, a novel cellulolytic bacterium was isolated from the rhizosphere of pine trees. This isolate was Gram-reaction positive, motile and rods, and formed terminal or subterminal ellipsoidal spores. S22^T represented positive activity for catalase, oxidase, esterase (C4), esterase lipase (C8), β-galactosidase, leucine arylamidase, and hydrolysis of esculin. It contained meso-diaminopimelic acid as the diagnostic dia-mino acid in the cell-wall. The predominant isoprenoid quinone was menaquinone 7 (MK-7), and the major cellular fatty acids were anteiso-C_15:0 (52.9%), iso-Ci_16:0 (11.3%), and iso-C_15:0 (10.0%). The DNA G+C content was 43.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that this isolate belonged to the family Paenibacillaceae. S22^T exhibited less than 97.0% 16S rRNA gene similarity with all relative type strains in the genus Paenibacillus, and the most closely related strains were Paenibacillus anaericanus MH21^T and Paenibacillus ginsengisoli Gsoil 1638^T, with equal similarities of 95.8%. This polyphasic evidence suggested that strain S22^T should be considered a novel species in the genus Paenibacillus, for which the name, Paenibacillus pini sp. nov., is proposed. The type strain is S22^T (=KCTC 13694^T =KACC 14198^T =JCM 16418^T)     

Plant growth‐promoting effects of native Pseudomonas strains on Mentha piperita (peppermint): an in vitro study

Plant growth‐promoting rhizobacteria (PGPR) affect growth of host plants through various direct and indirect mechanisms. Three native PGPR (Pseudomonas putida) strains isolated from rhizospheric soil of a Mentha piperita (peppermint) crop field near Córdoba, Argentina, were characterised and screened in vitro for plant growth‐promoting characteristics, such as indole‐3‐acetic acid (IAA) production, phosphate solubilisation and siderophore production, effects of direct inoculation on plant growth parameters (shoot fresh weight, root dry weight, leaf number, node number) and accumulation and composition of essential oils. Each of the three native strains was capable of phosphate solubilisation and IAA production. Only strain SJ04 produced siderophores. Plants directly inoculated with the native PGPR strains showed increased shoot fresh weight, glandular trichome number, ramification number and root dry weight in comparison with controls. The inoculated plants had increased essential oil yield (without alteration of essential oil composition) and biosynthesis of major essential oil components. Native strains of P. putida and other PGPR have clear potential as bio‐inoculants for improving productivity of aromatic crop plants. There have been no comparative studies on the role of inoculation with native strains on plant growth and secondary metabolite production (specially monoterpenes). Native bacterial isolates are generally preferable for inoculation of crop plants because they are already adapted to the environment and have a competitive advantage over non‐native strains.     

Bacillus locisalis sp. nov., a new haloalkaliphilic species from hypersaline and alkaline lakes of China, Kenya and Tanzania

A polyphasic taxonomic study was performed on seven Bacillus-like bacteria isolated from three hypersaline and alkaline lakes located in China, Kenya and Tanzania. All strains were moderately halophilic and alkaliphilic, Gram positive, motile rods. The DNA G+C content from the seven isolates ranged from 42.2 to 43.4 mol% and their major fatty acid was anteiso-C_15:0. Strain CG1^T, selected as representative strain of the isolates, possesses meso-diaminopimelic acid in the cell wall peptidoglycan, MK-7 as the predominant menaquinone and diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. Comparative 16S rRNA gene sequence analysis indicated that the isolates belonged to the genus Bacillus. The seven isolates shared 97.7–99.9% 16S rRNA gene sequence similarity, and formed a branch that was distinct from the type strains of the recognized species of the genus Bacillus. They were most closely related to Bacillus agaradhaerens DSM 8721^T (92.6–93.8% 16S rRNA sequence similarity). DNA–DNA hybridization values between the seven isolates were 85–100%. According to the polyphasic characterization, the strains represent a novel species, for which the name Bacillus locisalis sp. nov. is proposed. The type strain is CG1^T (CCM 7370^T = CECT 7152^T = CGMCC 1.6286^T = DSM 18085^T).     

Isolation and characterization of plant growth-promoting rhizobacteria from wheat roots by wheat germ agglutinin labeled with fluorescein isothiocyanate

Thirty-two isolates were obtained from wheat rhizosphere by wheat germ agglutinin (WGA) labeled with fluorescein isothiocyanate (FITC). Most isolates were able to produce indole acetic acid (65.6%) and siderophores (59.3%), as well as exhibited phosphate solubilization (96.8%). Fourteen isolates displayed three plant growth-promoting traits. Among these strains, two phosphate-dissolving ones, WS29 and WS31, were evaluated for their beneficial effects on the early growth of wheat (Triticum aestivum Wan33). Strain WS29 and WS31 significantly promoted the development of lateral roots by 34.9% and 27.6%, as well as increased the root dry weight by 25.0% and 25.6%, respectively, compared to those of the control. Based on 16S rRNA gene sequence comparisons and phylogenetic positions, both isolates were determined to belong to the genus Bacillus. The proportion of isolates showing the properties of plant growth-promoting rhizobacteria (PGPR) was higher than in previous reports. The efficiency of the isolation of PGPR strains was also greatly increased by WGA labeled with FITC. The present study indicated that WGA could be used as an effective tool for isolating PGPR strains with high affinity to host plants from wheat roots. The proposed approach could facilitate research on biofertilizers or biocontrol agents.     

Genetic diversity and plant-growth related features of <Emphasis Type="Italic">Burkholderia</Emphasis> spp. from sugarcane roots

Brazil is the largest sugarcane producer in the world, mainly due to the development of different management strategies. Recently, microbial-plant related studies revealed that bacterial isolates belonging to the genus Burkholderia are mainly associated with this plant and are responsible for a range of physiological activity. In this study, we properly evaluate the physiological activity and genetic diversity of endophytic and rhizospheric Burkholderia spp. isolates from sugarcane roots grown in the field in Brazil. In total, 39 isolates previously identified as Burkholderia spp. were firstly evaluated for the capability to fix nitrogen, produce siderophores, solubilise inorganic phosphates, produce indole-acetic acid and inhibit sugarcane phytopathogens in vitro. These results revealed that all isolates present at least two positive evaluated activities. Furthermore, a phylogenetic study was carried out using 16S rRNA and gyrB genes revealing that most of the isolates were affiliated with the Burkholderia cepacia complex. Hence, a clear separation given by endophytic or rhizospheric niche occupation was not observed. These results presented an overview about Burkholderia spp. isolates from sugarcane roots and supply information about the physiological activity and genetic diversity of this genus, given direction for further studies related to achieve more sustainable cultivation of sugarcane.