In vitro screening of siderophore-producing rice root endophytic bacteria from up-land paddies in north-western Vietnam for plant growth-promoting activities

Aims@#Endophytic bacteria (EB) living inside plant tissues possess different beneficial traits including siderophore production and other plant growth-promoting (PGP) activities. Siderophore-producing EB promote host plant growth by secreting ferrum in iron-deficient conditions. This study screened 19 siderophore producers in vitro, isolated from upland rice roots grown in mountain farms of Tung Village, Nậm Có Commune, Mù Cang Chải District, Yên Bái Province, Vietnam, for PGP traits, including phosphate solubilisation, indole-3-acetic acid (IAA), ammonia, gelatinase, amylase and catalase production.@*Methodology and results@#The bacteria were identified by Matrix assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-TOF MS). All 19 isolates were identified as genera Pseudomonas, Enterobacter, Pantoe, Bacillus, Burkholderia, Staphylococcus, Ralstonia and Cronotacter. The isolates produced catalase and ammonia. The amount of ammonia ranged from 60.74 ± 0.14 to 466.72 ± 0.18 mg/L. Out of the 19 siderophore producers, 17 (89.47%) were able to solubilise phosphate with solubilisation index (PSI) ranging from 1.12 ± 0.07 to 2.14 ± 0.15. The qualitative assays identified 12 isolates (63.15%) positive for IAA production with a tryptophan concentration of 5 mM, whereas 15 (78.94%) and 17 (89.47%) isolates were positive for gelatin and starch hydrolysis, respectively. Especially, 7 isolates were found to be positive for all tested assays in vitro including Pseudomonas rhodesiae (NC2), Enterobacter asburiae (NC50), Pantoea ananatis (NC63), Bacillus cereus (NC64), Burkholderia cenocepacia (NC110), Staphylococcus sciuri (NC112) and Ralstonia pickettii (NC122).@*Conclusion, significance and impact of study@#This study serves as crucial findings of multi-trait plant growth-promoting endophytic bacteria isolated from upland rice root in north-western Vietnam. The seven potential isolates positive for all tested assays could be effective PGP bacteria for bio-inoculants.

Genome analysis and plant growth promoting activity of Pseudonocardia strain DR1-2 from the root of Dendrobium christyanum Rchb.f

Aims@#The objective of this study was to analyze the genome of endophytic actinomycete associated with orchids and evaluate its plant hormone activities, including phytohormone, siderophore, ammonia production, zinc and phosphate solubilization.@*Methodology and results@#Strain DR1-2 isolated from the roots of the Thai orchid, Dendrobium christyanum Rchb.f., was closely related to Pseudonocardia alni DSM 44104T, P. antarctica DSM 44749T and P. carboxydivorans Y8T (99.93-100% similarity) based 16S rRNA gene sequence. This strain exhibited IAA production (294.10 ± 12.17 μg/mL), phosphate solubilization (2.20 ± 0.08 solubilization Index, SI), positive for siderophore production and ammonia production (36.99 ± 2.24 μg/mL). It showed a maximum IAA of 489.73 ± 8.90 μg/mL, when optimized using 0.5% Ltryptophan, pH 6 and incubated at 30 °C for 7 days. The IAA of strain enhanced the root length, shoot length, number of roots and fresh weight of rice seedlings (Oryza sativa L. cv. RD49). The draft genome of strain DR1-2 was 6,077,423 bp in 23 contigs with G+C content of 74.6%. The average nucleotide identity-Blast (ANIb) and average nucleotide identity-MUMmer (ANIm) values of strain DR1-2 and related type strains were 95.81 to 97.25% and the digital DNA-DNA hybridization (dDDH) values were 72.60 to 74.00%, respectively. Genomic analysis of strain DR1-2 revealed that the gene encodes the enzyme involved in the phytohormones biosynthesis and gene clusters involved in the biosynthesis of bioactive metabolites.@*Conclusion, significance and impact of study@#Endophytic actinomycete, Pseudonocardia strain DR1-2 from Thai orchid, D. christyanum Rchb.f., exhibited significant IAA production and affected the growth of the plant, which was the potential source of plant hormones for agricultural applications.

Effects of plant growth-promoting rhizobacteria Klebsiella michiganensis TS8 and Lelliottia jeotgali MR2 on the growth and cadmium uptake of Arabidopsis thaliana under cadmium stress / 生物工程学报

In this study, the effects of two plant growth-promoting bacteria Klebsiella michiganensis TS8 and Lelliottia Jeotgali MR2 on the growth and cadmium (Cd) uptake of Arabidopsis thaliana under Cd stress were explored. A wild-type Arabidopsis thaliana was selected as the experimental plant and was planted at different Cd concentrations. MR2 and TS8 bacterial suspensions were sprayed onto the rhizospheric soil during the planting process. The initial Cd concentration of the bought soil was 14.17 mg/kg, which was used as the pot soil of the low-concentration Cd treatment group (LC). The concentration of soil Cd at high-concentration Cd treatment group (HC) were 200 mg/kg higher than that at LC group. Compared with the control group, MR2 suspension significantly promoted the growth of A. thaliana at both low and high concentrations, while TS8 strain and MR2_TS8 mixture only exhibited growth-promoting effect at high concentration. However, it was noteworthy that, TS8 suspension significantly reduced the Cd content in the underground parts of A. thaliana (60% and 59%), and significantly improved the Cd content in the aboveground parts of A. thaliana (234% and 35%) at both low and high concentrations. In addition, at low concentration, both single strain and mixed strains significantly improved the transformation from reducible Cd to acid-extractable Cd in soil, promoted Cd intake, and thereby reduced the total Cd content in soil. Therefore, the rational application of plant growth-promoting bacteria may improve crop yield and remediate Cd contamination in soil.

Endophytic bacteria Bacillus safensis and Pseudomonas hibiscicola and their ability to increase rice seedling growth

Endophytic bacteria Bacillus safensis RS95 and Pseudomonas hibiscicola RS121 were evaluated for their ability to promote the growth of rice seedlings and produce indole-acetic acid (IAA) and siderophores and to solubilize phosphates. 'Guri' rice seeds were immersed in bacterial endophyte cell suspensions (separated and two-strain mixed), as well as in Escherichia coli DH5α, phosphate-buffered saline (PBS) and water treatments (negative controls). Seeds were sown on agar-water in Petri plates placed vertically at an angle of 65°. The ability of plant growth-promoting endophytic bacteria (PGPEB) to produce IAA and siderophores was determined by Salkowski colorimetric and chrome azurol S (CAS) assays, respectively. Mineral phosphate solubilization activity was calculated by inoculating the endophytes onto medium containing insoluble phosphate. PGPEB showed a positive effect on the growth of rice seedlings, causing a mean growth of shoots and primary-roots of 60 and 67%, respectively. Bacterial strains also showed positive traits for IAA and siderophore production, as well as phosphate-solubilization activity

Effects of Plant Growth-promoting Rhizobacteria on Physiological Characteristics and Inorganic Elements in Paris polyphylla var. yunnanensis / 中国实验方剂学杂志

ObjectiveTo study the effects of different plant growth-promoting rhizobacteria （PGPR） on the growth of Paris polyphylla var. yunnanensis seedlings and the quality of its medicinal parts， in order to provide reference for the cultivation of high-quality P. polyphylla var. yunnanensis. MethodThe pot culture experiment at room temperature and the single-factor completely random design were employed for exploring the effects of five PGPR on physiological characteristics and inorganic elements of P. polyphylla var. yunnanensis. ResultThe results showed that the exogenous inoculation of different PGPR promoted the growth and development of P. polyphylla var. yunnanensis to varying degrees， delayed the senescence of leaves， and improved the medicinal value of new and old rhizomes. Compared with the non-inoculated control， the exogenous inoculation of compound microbial fertilizer （FH） and microbial agent Sanju Guanjin liquid （SJ） enhanced the root vigor， increased the content of photosynthetic pigments and the activities of anti-oxidant enzymes ［superoxide dismutase （SOD）， catalase （CAT）， and peroxidase （POD）］， and reduced the content of malondialdehyde （MDA） in leaves. Their inhibition rates against MDA were 10.46%-39.62% and 20.99%-53.12%， respectively. With the growth of P. polyphylla var. yunnanensis， the inhibition rate against MDA gradually increased， which effectively delayed the senescence of P. polyphylla var. yunnanensis leaves. In addition， the exogenous inoculation of different PGPR promoted the accumulation of nutrient elements in new and old rhizomes， lowered the heavy metal content to varying degrees， and improved the medicinal value of P. polyphylla var. yunnanensis rhizomes. ConclusionFH and SJ have exhibited the best promoting effect on the growth of P. polyphylla var. yunnanensis seedlings and also the best regulatory effect on the medicinal value of P. polyphylla var. yunnanensis rhizomes， which has provided reference for the application and promotion of PGPR in the growth of P. polyphylla var. yunnanensis.

Effect of Two Kinds of Compound Rhizosphere Growth-promoting Bacteria on Growth，Physiological Characteristics and Pharmacodynamic Components of Angelicae Sinensis Radix / 中国实验方剂学杂志

ObjectiveTo study the effects of foliar spraying of two kinds of compound rhizosphere growth-promoting agents on the growth and physiological characteristics of Angelicae Sinensis Radix （ASR）， as well as the pharmacodynamic components， in order to lay a foundation for providing functional microbial agents for ecological cultivation of ASR. MethodThe compound growth-promoting agents T1 （Pseudomonas CBS5， CBS7 and CBSB） and T2 （Bacillus 5C1， 5C5 and 5C7） with the concentration of 1×108 CFU·mL-1 were sprayed on the leaf surface of the field， and the sterile potato glucose broth medium was used as the control （CK）. The plant growth indexes of ASR were measured by conventional methods， the photosynthetic physiological indexes of ASR were measured by portable photosynthetic measurement system， the enzyme activities of plants and microorganisms were measured by kit method， and the endogenous hormone levels were analyzed by ultra-performance liquid chromatography tandem mass spectrometry. The contents of ferulic acid， senkyunolide I， coniferyl ferulate， senkyunolide A and Z-ligustilide were determined by high performance liquid chromatography. ResultCompared with CK， the two compound inoculants could promote the growth of ASR and increase the biomass， increase the leaf net photosynthetic rate， stomatal conductance， intercellular CO2 concentration， transpiration rate， increase catalase， peroxidase， superoxide dismutase， polyamine oxidase， diamine oxidase and polyphenol oxidase enzyme activities， increase endogenous jasmonic acid， cytokinin and gibberellin levels in plants， increase the contents of ferulic acid， senkyunolide A and Z-ligustilide， reduce the contents of malondialdehyde and abscisic acid， and reduce the incidence of root rot. ConclusionFoliar spraying of two kinds of rhizosphere compound growth-promoting agents can promote the growth， photosynthesis and stress resistance of ASR， and can improve the quality of ASR in different degrees. Comprehensive analysis shows that T1 treatment is better than T2 treatment in the growth-promoting and quality-enhancing of ASR.

Indigenous bacterial community of heavy metal tolerance in the rhizosphere soils of Mimosa pudica naturally growing on an ex-tin mining area

Aims@#The purpose of this research was to explore the composition and genomic functions of bacterial community inhabiting the rhizosphere of Mimosa pudica, which were naturally growing on tailing and non-tailing soils of an ex-tin mining area.@*Methodology and results@#DNA were extracted from rhizosphere soils and PCR targeting the hypervariable region V3-V4 was carried out by Illumina 16S metagenomic library. Libraries were sequenced using Illumina MiSeq. The Operational Taxonomic Units (OTUs) were assigned to 23 bacterial phyla, 72 classes, 165 orders, 248 families and 357 genera. The most represented and dominant phylum was Proteobacteria, with an average abundance value of 41.2%. The most represented genera included Paraburkholderia, Bradyrhizobium, Bacillus, Candidatus, Acidothermus, Acidibacter and Nitrospira. Non-tailing soils had more number and richness of species while the tailings had more diversity of species. The metagenomes accommodate suspected genes for heavy metal tolerance of microbes (As, Cr, Co, Zn, Ni, Cu, Cd, Fe and Hg) and microbial plant-growth-promoting traits for hyperaccumulator plants (synthesis of indole acetic acid (IAA), siderophore and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase; solubilization of phosphate and potassium and nitrogen fixation). @*Conclusion, significance and impact of study@#Bacteria and predicted genes discovered could be part of major factors influencing growth of M. pudica in heavy metal-contaminated soils. The study provides the first report and a basis into the bacterial community associated with M. pudica in ex-tin mining soils from the studied geographical location. The findings also provide fundamental knowledge on phytoremediation potential of heavy metal contaminated soils involving indigenous beneficial microbial populations.

Identification and characterization of plant growth-promoting properties of bacterial endophytes from selected Zingiberaceae plants

Aims@#This study aims to isolate, characterize and screen the plant growth-promoting bacteria from Zingiberaceae plants. Plant promoting activities such as indole-3-acetic acid (IAA), phosphate solubilization, zinc solubilization and nitrogen-fixing capabilities are determined, and the IAA production of selected isolates are optimized. @*Methodology and results@#Endophytic bacteria were isolated from the plant samples by surface sterilization on nutrient agar (NA) plates and incubated at 30 °C for 2-3 days. The bacteria were identified based on their phenotypic characteristics and 16S rRNA gene sequence analyses. All isolates were identified as genera Bacillus, Lysinibacillus, Kerstersia, Klebsiella and Brucella. The isolates exhibited phosphate solubilization (1.5 ± 0.75-37.5 ± 8.75 Solubilization Index, SI), zinc solubilization (2.5 ± 0-60 ± 1.5 SI) and IAA production (0.1 ± 0.2-115.7 ± 1.6 µg/mL), while 3 isolates possessed nitrogen-fixing capabilities. Five isolates (PHAS-2, PWS-2, PWR-2, PHBS-2 and SCG-2) were selected for IAA optimization. Isolate PWR-2 produced the maximum IAA at 447.7 ± 0 µg/mL when tryptophan concentration was maintained at 1.0%.@*Conclusion, significance and impact of study@#Genera of bacteria included Bacillus, Lysinibacillus, Kerstersia, Klebsiella and Brucella were successfully isolated from Zingiberaceae plants. All the isolates showed the capability to produce IAA, while some isolates exhibited phosphate solubilization and zinc solubilization, and a few possessed nitrogen-fixing capabilities. The potential IAA production isolates could be applied for the enhancement of agricultural production that will be becoming a more widely accepted practice.

Initial development of upland rice plants inoculated with the MAY12 strain of Azospirillum spp / Desenvolvimento inicial de plantas de arroz de terras altas inoculadas com a estirpe MAY12 de Azospirillum spp

ABSTRACT: The purpose of this study was to evaluate the contribution of the inoculation of the strain Azospirillum MAY12 to the development of rice plants of the cultivar BRS Esmeralda. A completely randomized experiment was performed in a greenhouse, with 8 treatments and 6 repetitions, namely, commercial inoculant (CI) containing strains of Azospirillum brasilense ABV5 and ABV6 (T1), MAY12 (T2), nitrogen control with 50 mg of N or full dose (T3), CI + 30% of N (percentage referring to full dose) (T4), CI + 60% N (T5), MAY12 + 30% N (T6), MAY12 + 60% N (T7) and absolute control (T8). There was a significant increase in the fresh and dry mass of the shoot and roots, height, root volume, and the number of tillers and leaves of plants with the MAY12 inoculation (with and without N added) compared to T8. Treatments containing MAY12 + N increased the total dry mass by ~920% compared to T8, matching the T3 yield. The inoculation of MAY12 in isolation was as efficient as the application of the full dose of N, resulting in an increase of ~115% in height and 373% in root volume of the plants compared to T8. The MAY12 strain demonstrated good performance in the development of the cultivar, which was comparable to the CI in the variables tested. Therefore, inoculation with the MAY12 strain is promising for the partial reduction of nitrogen fertilizers in upland rice cultivation.

RESUMO: O objetivo deste trabalho foi avaliar a contribuição da inoculação da estirpe de Azospirillum MAY12 no desenvolvimento de plantas de arroz da cultivar BRS Esmeralda. Foi realizado um experimento inteiramente casualizado em casa de vegetação, tendo oito tratamentos e seis repetições: inoculante comercial (IC) contendo as estirpes de Azospirillum brasilense AbV5 e AbV6 (T1), MAY12 (T2), testemunha nitrogenada com 50 mg de N ou dose cheia (T3), IC + 30% de N (percentual referente à dose cheia) (T4), IC + 60% de N (T5), MAY12 + 30% de N (T6), MAY12 + 60% de N (T7) e testemunha absoluta (T8). Houve aumento significativo da massa fresca e seca da parte aérea e de raízes, altura, volume de raízes e do número de perfilhos e de folhas das plantas com a inoculação de MAY12 (com e sem adição de N) em relação a T8. Os tratamentos contendo MAY12 + N aumentaram em torno de 920% a massa seca total em relação a T8, equiparando-se ao rendimento T3. A inoculação de MAY12, isoladamente, foi tão eficiente quanto a aplicação da dose cheia de N para o aumento em torno de 115% da altura e de 373% do volume de raízes das plantas em relação a T8. A estirpe MAY12 apresentou bom desempenho no desenvolvimento da cultivar equiparando-se com o IC nas variáveis testadas. Portanto, a inoculação com a estirpe MAY12 mostra-se promissora para a redução parcial de fertilizantes nitrogenados no cultivo de arroz de terras altas.

Screening of plant growth-promoting rhizobacteria and its effect on seed germination of Polygonum multiflorum / 中国中药杂志

In this study, the rhizobacteria and actinomycetes of Polygonum multiflorum were screened for the strains with indole acetic acid(IAA)-producing capacity by Salkowski method, the siderophore-producing strains by Chrome Azurol S(CAS) assay, and the strains with inorganic phosphorus-solubilizing capacity by PKO inorganic phosphorus medium. The strains were identified by morphological identification, physiological and biochemical characteristics, and 16 S rDNA sequences. Furthermore, the effect of growth-promoting strains on the seed germination and development of P. multiflorum was tested. The results showed that among 196 strains, two strains F17 and F42 were found to be capable of producing IAA and siderophore and solubilizing inorganic phosphorus simulta-neously. For F17 and F42, the results are listed below: 38.65 and 33.64 mg·L~(-1) for IAA production, 0.85 and 0.49 for siderophore-producing capacities(A_s/A_r), and 1.35 and 1.70 for inorganic phosphorus-solubilizing capacities(D/d), respectively. Comprehensive analysis revealed that strains F17 and F42 were identified as Pseudochrobactrum asacharolyticum and Bacillus aryabhattai, respectively, and both could significantly promote the seed germination of P. multiflorum.

Screening of plant growth promoting rhizobacteria for antifungal activity against Fusarium oxysporum

Aim: New species of Plant Growth Promoting Rhizobacteria (PGPR), with varying growth promoting and biocontrol ability are often being discovered. They facilitate plant growth either directly by secreting nutrients and hormones or indirectly by providing defence mechanism to the plant. The present study was undertaken to isolate PGPR from the rhizosphere of Solanum lycopersicum and Arachis hypogaea, and test their growth promoting ability and antifungal activity against Fusarium oxysporum. Methodology: PGPRs were isolated from the rhizosphere of S. lycopersicum and A. hypogaea by serial dilution of the rhizospheric soil and identified by 16s rDNA sequencing. The isolates were analysed for antifungal activity against F. oxysporum, indole 3-acetic acid (IAA) production and phosphate solubilisation. For the growth promotion assay, aseptically grown Vigna radiata seedlings were dipped separately in isolated bacterial suspension of PGPR (109 CFU ml-1) and planted in autoclaved soil. Plants were irrigated with 50% Hoagland solution for every 48 hr and maintained at 25 ± 2 °C with 16/8 hr of light and dark photoperiod. Growth promotion was examined in terms of differences in shoot length, root length, fresh weight and dry weight after 12 days of treatment. Results: Six isolates were found to have antifungal activity towards plant pathogen, F. oxysporum. Five isolates showed similarity to Pseudomonas aeruginosa (B7-1, B11-5, B3-1, Rh-1, Rh-2) and one to Pseudomonas putida (B53). All six strains were able to produce IAA, where B53 and B13-1 showed the highest production compared to other strains. P. putida B53 demonstrated the highest plant growth promotion activity by significantly (p<0.05) increasing the growth of V. radiata plants as evidenced by increase in shoot length, root length, fresh and dry weight. Interpretation: The results obtained from the present study supports that PGPRs like Pseudomonas sp. could serve as potential eco-friendly bio-fertilizer and bio- fungicide

Efficacy of alginate- and clay-encapsulated microorganisms on the growth of Araçá-Boi seedlings (Eugenia stipitata)

The present work aimed to evaluate the effects of encapsulated microorganisms on seedlings of Eugenia stipitata, popularly known as araçá-boi, to evaluate the interaction between the inoculum and encapsulating agents such as clay and alginate. The experiment was carried out in a completely randomized design using a 3×2 factorial scheme. The treatments were control, inoculum, clay without microbial inoculum, clay with microbial inoculum, alginate without microbial inoculum, and alginate with microbial inoculum. The seedlings were grown under nursery conditions over a period of 3 months. No treatment increased the height, stem diameter, shoot dry matter or root dry matter of the araçá-boi seedlings. The use of alginate increased the ammonium content compared to the clay and control treatments. Alginate and clay increased the nitrate content in relation to the control. Alginate increased the total number of bacteria in relation to the clay and control treatments. The application of inoculum combined with alginate increased the nitrate content only in relation to the clay and control treatments. Although the application of inoculum promoted an increase in the nitrate content compared to the uninoculated treatments, there was no effect for the other parameters analyzed. The results suggest that clay and alginate encapsulating agents with the presence or absence of microorganisms may improve some soil parameters.

Effect of bio-liquid organic fertilizer on the growth of Dipterocarpus alatus Roxb seedlings in the pot experiment

Aims@#The objective of this research was to study the effect of bio-liquid organic fertilizer on the growth of Dipterocarpus alatus Roxb seedlings (30 days old) in the pot experiment. @*Methodology and results@#For the production of bio-liquid fertilizers, distillery slop; molasses and bio-methane waste water were fermented with plant growth promoting bacteria, which had potentials for nitrogen fixing, phosphate solubilizing and potassium solubilizing properties. It was found that treatment no. 13 (molasses + three bacterial isolates (PGPB), 30 days of fermentation) presented the best result on the growth parameters of D. alatus Roxb including root length (21.67 cm), shoot height (20.33 cm), root fresh weight (1.49 g), shoot fresh weight (3.61 g) and total biomass (4.13 g). Moreover, using liquid organic fertilizer produced from molasses supplemented with bacteria had higher growth-promoting effects on D. alatus than the effective microorganisms (EM). @*Conclusion, significance and impact of study@#To covert agricultural residues to the valuable product was the aim of this work. In our experiment, we found that molasses and bio-methane waste water were suitable for using as a material to produce liquid organic fertilizers which were beneficial for promoting growth of D. alatus seedlings.

Changes induced by co-inoculation in nitrogen-carbon metabolism in cowpea under salinity stress

ABSTRACT To mitigate the deleterious effects of abiotic stress, the use of plant growth-promoting bacteria along with diazotrophic bacteria has been increasing. The objectives of this study were to investigate the key enzymes related to nitrogen and carbon metabolism in the biological nitrogen fixation process and to elucidate the activities of these enzymes by the synergistic interaction between Bradyrhizobium and plant growth-promoting bacteria in the absence and presence of salt stress. Cowpea plants were cultivated under axenic conditions, inoculated with Bradyrhizobium and co-inoculated with Bradyrhizobium sp. and Actinomadura sp., Bradyrhizobium sp. and Bacillus sp., Bradyrhizobium sp. and Paenibacillus graminis, and Bradyrhizobium sp. and Streptomycessp.; the plants were also maintained in the absence (control) and presence of salt stress (50 mmolL-1 NaCl). Salinity reduced the amino acids, free ammonia, ureides, proteins and total nitrogen content in nodules and increased the levels of sucrose and soluble sugars. The co-inoculations responded differently to the activity of glutamine synthetase enzymes under salt stress, as well as glutamate synthase, glutamate dehydrogenase aminating, and acid invertase in the control and salt stress. Considering the development conditions of this experiment, co-inoculation with Bradyrhizobium sp. and Bacillus sp. in cowpea provided better symbiotic performance, mitigating the deleterious effects of salt stress.

Enhancement of Plant Growth and Yield of Wheat (Triticum aestivum L.) under Drought Conditions Using Plant-growth-promoting Bacteria

To reduce negative effects of drought on plants, the use of plant growth- promoting rhizobacteria (PGPR) is an effective way to investigate that. The aim of the present study was to assess the bacterial characteristics Bacillus subtilis, Bacillus cereus, Pseudomonas koreensis, Pseudomonas fluroscence, and Enterobacter cloacae as growth, IAA production, phosphate solubilization, seed germination under different concentrations of polyethylene glycol (PEG 6000), and their efficacy of single or dual inoculation with two superior strains in lyzimeter experiment for improving growth and yield of sensitive variety of wheat (Triticum aestivum L.) cv. Sids 1 under different stress irrigation water 100, 70 and 35% of field capacity. Among the tested strains only 2 strains B. subtilis and P. koreensis showed a stable growth even in the maximum 40% PEG concentration. Also, P. koreensis produced the highest amount of IAA (1.84 µg ml-1), and solubilise maximum amount of P (1.59 µg ml-1), and improved seed germination at 30% PEG concentration. On the other hand, in gnotobiotic sand system experiment, PGPR increase growth dynamics as well as proline content and root colonisation of wheat plants over uninoculated control under drought-stressed conditions. In lyzimeter experiment, single and dual inoculation treatments showed a significant increase of physiological and biochemical parameters of the plant under different drought stress treatments. Also, maximum increase 29.08 % in ascorbate peroxidase and 27.38% in catalase activities due to dual inoculation treatments T12 (Inoculation with B. subtilis + P. koreensis and irrigated at field capacity 35%), with respect to the corresponding unstressed control T10 (Inoculation with B. subtilis + P. koreensis and irrigated at field capacity 100%). Also, significant increase in grain yield, straw yield, biological yield and harvest index were observed under different drought stress. These results may be related to increase uptake of water and nutrients in wheat plant and reflected in better plant growth and yield.

Antagonistic endophytic bacteria associated with nodules of soybean (Glycine max L. ) and plant growth-promoting properties

Abstract A total of 276 endophytic bacteria were isolated from the root nodules of soybean (Glycine max L.) grown in 14 sites in Henan Province, China. The inhibitory activity of these bacteria against pathogenic fungus Phytophthora sojae 01 was screened in vitro. Six strains with more than 63% inhibitory activities were further characterized through optical epifluorescence microscopic observation, sequencing, and phylogenetic analysis of 16S rRNA gene, potential plant growth-promoting properties analysis, and plant inoculation assay. On the basis of the phylogeny of 16S rRNA genes, the six endophytic antagonists were identified as belonging to five genera: Enterobacter, Acinetobacter, Pseudomonas, Ochrobactrum, and Bacillus. The strain Acinetobacter calcoaceticus DD161 had the strongest inhibitory activity (71.14%) against the P. sojae 01, which caused morphological abnormal changes of fungal mycelia; such changes include fracture, lysis, formation of a protoplast ball at the end of hyphae, and split ends. Except for Ochrobactrum haematophilum DD234, other antagonistic strains showed the capacity to produce siderophore, indole acetic acid, and nitrogen fixation activity. Regression analysis suggested a significant positive correlation between siderophore production and inhibition ratio against P. sojae 01. This study demonstrated that nodule endophytic bacteria are important resources for searching for inhibitors specific to the fungi and for promoting effects for soybean seedlings.

Mangrove endophyte promotes reforestation tree (Acacia polyphylla) growth

ABSTRACT Mangroves are ecosystems located in the transition zone between land and sea that serve as a potential source of biotechnological resources. Brazil's extensive coast contains one of the largest mangrove forests in the world (encompassing an area of 25,000 km2 along all the coast). Endophytic bacteria were isolated from the following three plant species: Rhizophora mangle, Laguncularia racemosa and Avicennia nitida. A large number of these isolates, 115 in total, were evaluated for their ability to fix nitrogen and solubilize phosphorous. Bacteria that tested positive for both of these tests were examined further to determine their level of indole acetic acid production. Two strains with high indole acetic acid production were selected for use as inoculants for reforestation trees, and then the growth of the plants was evaluated under field conditions. The bacterium Pseudomonas fluorescens (strain MCR1.10) had a low phosphorus solubilization index, while this index was higher in the other strain used, Enterobacter sp. (strain MCR1.48). We used the reforestation tree Acacia polyphylla. The results indicate that inoculation with the MCR1.48 endophyte increases Acacia polyphylla shoot dry mass, demonstrating that this strain effectively promotes the plant's growth and fitness, which can be used in the seedling production of this tree. Therefore, we successfully screened the biotechnological potential of endophyte isolates from mangrove, with a focus on plant growth promotion, and selected a strain able to provide limited nutrients and hormones for in plant growth.

The effect of FRAW towards the growth of chilli seedlings and its associated microorganisms

Abstract@#This study aims to evaluate the effect of Fermented Rice After-wash Water (FRAW) on chilli growth and to isolate microorganism present in three brands of white rice FRAW. The study showed that FRAW treatment was comparable with NPK fertiliser. In addition, a number of plant growth-promoting microbes associated with FRAW were also isolated. Isolated bacteria and fungi were then characterised according to their morphology and biochemical analysis. Thus the positive effect of FRAW on the chilli was likely due to the plant growth promoting microorganism present in FRAW.

Diversity, antibacterial activites and growth promoting characteristics of endophytic fungi from sandal (Santalum album) / 中国中药杂志

The aim of this study was to investigated the biological diversity, antibacterial activites and the plant growth-promoting traits of endophytic fungi of sandal (Santalum album), and to assess their potential in the development of antibacterial substances and rapid cultivation of sandal. The results of isolation and taxa analysis of endophytic fungi from sandal showed that 325 strains of endophytic fungi belonging to 16 genera of endophytic fungi were isolated from sandal (of which 86 from roots, 105 from stems and 134 from leaves). The isolation rate and colonization rate of endophytic fungi in different sandal parts showed the same pattern of change: leave>stems>roots. The diversity index of endophytic fungi in sandal roots was significantly higher than that of stems and leaves. The dominant endophytic fungi of sandal roots, stems and leaves showed significant differences. The dominant endophytic fungi of roots were Fusarium (50.00%) and Alternaria (10.47%), Alternaria (58.11%) and Acremonium (20.00%) for stems, and Pantoea (74.63%) for leaves. The antibacterial activity of 40 representative strains of sandal endophytic fungi were analyzed and the results showed that 90% of endophytic fungi exhibited inhibitory activity against at least one of the tested bacteria strains, and the strains with inhibitory activity to Escherichia coli, Enterobacter aerogenes, Shigella dysenteriae, Salmonella typhimurium, Staphylococcus aureus, and Bacillus subtilis accounted for 45.0%, 30%, 47.5%, 55%, 72.5%, and 62.5%, respectively. The sandal fungal endophytes with plant growth-promoting characteristics were screened, and 5 strains of endophytic fungi with phosphorus-solubilizing activity, 8 strains of endophytic fungi producing IAA, and 4 strains of endophytic fungi producing siderophores were found. Among them, endophytic fungus Monilia sp TXRF45 clould produced IAA and siderophores, and also show phosphate-solubilizing activity. The results indicated that the endophytic fungi of Sandal were rich in species diversity and their distribution had a certain tissue specificity. Some strains showed good antibacterial activity and growth-promoting properties, which could potentially applicable for the development of antibacterial substances and rapid cultivation of sandal.

Aspergillus terreus JF27 Promotes the Growth of Tomato Plants and Induces Resistance against Pseudomonas syringae pv. tomato

Certain beneficial microorganisms isolated from rhizosphere soil promote plant growth and induce resistance to a wide variety of plant pathogens. We obtained 49 fungal isolates from the rhizosphere soil of paprika plants, and selected 18 of these isolates that did not inhibit tomato seed germination for further investigation. Based on a seed germination assay, we selected four isolates for further plant tests. Treatment of seeds with isolate JF27 promoted plant growth in pot tests, and suppressed bacterial speck disease caused by Pseudomonas syringae pathovar (pv.) tomato DC3000. Furthermore, expression of the pathogenesis-related 1 (PR1) gene was higher in the leaves of tomato plants grown from seeds treated with JF27; expression remained at a consistently higher level than in the control plants for 12 h after pathogen infection. The phylogenetic analysis of a partial internal transcribed spacer sequence and the β-tubulin gene identified isolate JF27 as Aspergillus terreus. Taken together, these results suggest that A. terreus JF27 has potential as a growth promoter and could be used to control bacterial speck disease by inducing resistance in tomato plants.