Utilizing Alcohol for Alkane Biosynthesis by Introducing a Fatty Alcohol Dehydrogenase.

Alkanes produced by microorganisms are expected to be an alternative to fossil fuels as an energy source. Microbial synthesis of alkanes involves the formation of fatty aldehydes via fatty acyl coenzyme A (acyl-CoA) intermediates derived from fatty acid metabolism, followed by aldehyde decarbonylation to generate alkanes. Advancements in metabolic engineering have enabled the construction of such pathways in various microorganisms, including Escherichia coli. However, endogenous aldehyde reductases in the host microorganisms are highly active in converting fatty aldehydes to fatty alcohols, limiting the substrate pool for alkane production. To reuse the alcohol by-product, a screening of fatty alcohol-assimilating microorganisms was conducted, and a bacterial strain, Pantoea sp. strain 7-4, was found to convert 1-tetradecanol to tetradecanal. From this strain, an alcohol dehydrogenase, PsADH, was purified and found to be involved in 1-tetradecanol-oxidizing reaction. Subsequent heterologous expression of the PsADH gene in E. coli was conducted, and recombinant PsADH was purified for a series of biochemical characterizations, including cofactors, optimal reaction conditions, and kinetic parameters. Furthermore, direct alkane production from alcohol was achieved in E. coli by coexpressing PsADH with a cyanobacterial aldehyde-deformylating oxygenase and a reducing system, including ferredoxin and ferredoxin reductase, from Nostoc punctiforme PCC73102. The alcohol-aldehyde-alkane synthetic route established in this study will provide a new approach to utilizing fatty alcohols for the production of alkane biofuel. IMPORTANCE Alcohol dehydrogenases are a group of enzymes found in many organisms. Unfortunately, studies on these enzymes mainly focus on their activities toward short-chain alcohols. In this study, we discovered an alcohol dehydrogenase, PsADH, from the bacterium Pantoea sp. 7-4, which can oxidize 1-tetradecanol to tetradecanal. The medium-chain aldehyde products generated by this enzyme can serve as the substrate of aldehyde-deformylating oxygenase to produce alkanes. The enzyme found in this study can be applied to the biosynthetic pathway involving the formation of medium-chain aldehydes to produce alkanes and other valuable compounds.

Comparative proteomic analysis of saline tolerant, phosphate solubilizing endophytic Pantoea sp., and Pseudomonas sp. isolated from Eichhornia rhizosphere.

Soil salinization is a major stress affecting crop production on a global scale. Application of stress tolerant plant growth promoting rhizobacteria (PGPR) in saline soil can be an ideal practice for improving soil fertility. Rhizospheric microbiota of stress tolerant Eichhornia crassipes was screened for saline tolerant phosphate solubilizing bacteria, and the two isolates showing maximum solubilization index at 1 M NaCl were subjected to further analyses. The isolates were identified as Pantoea dispersa and Pseudomonas aeruginosa. Among the two isolates, P. dispersa PSB1 showed better phosphorus (P) solubilization potential under saline stress (335 ± 30 mg/L) than P. aeruginosa PSB5 (200 ± 24 mg/L). The mechanisms of P-solubilization, such as the production of organic acids and phosphatase were found to be influenced negatively by saline stress. The adaptive mechanisms of the isolates to overcome salt stress were analyzed by protein profiling which revealed salt stress induced modulations in protein expression involved in amino acid biosynthesis, carbon metabolisms, chemotaxis, and stress responses. Survival mechanisms such as protein RecA, LexA repressor and iron-sulfur cluster synthesis were upregulated in both the organisms under saline stress. P. dispersa PSB1 showed improved defense mechanisms such as the production of osmotolerants, redox enzymes, and quorum quenchers under saline stress, which may explain its better P solubilization potential than the P. aeruginosa PSB5. This study emphasizes the need for molecular approaches like proteome analysis of PGPR for identifying novel traits like stress tolerance and plant growth promotion before developing them as biofertilizers and biocontrol formulations.

Effects of Pb-, Cd-resistant bacterium Pantoea sp. on growth, heavy metal uptake and bacterial communities in oligotrophic growth substrates of Lolium multiflorum Lam.

Phosphate-solubilizing bacteria (PSB) can accelerate phytoremediation, especially in those fertilized soils. However, PSB function in oligotrophic growth substrates remains poorly studied. In this study, we isolated lead (Pb)- and cadmium (Cd)-resistant PSB from contaminated sandy soil at an abandoned lubricant plant. The isolated Pantoea sp. PP4 (PP4 hereafter) can produce organic acid and IAA (Indole-3-acetic acid) and dissolve up to 238 mg/L of inorganic phosphate Ca2(PO4)3, exhibiting biosorption capability for Pb and bioprecipitation for Pb and Cd. In the sand pot experiment, inoculation of PP4 increased the accumulation of Pb and Cd in Lolium multiflorum Lam. by 28.9% and 95.5%, respectively, and increased the available phosphorous in oligotrophic river sand by 30.8% (P < 0.05). Meanwhile, the growth of Lolium multiflorum Lam. was also stimulated, resulting in 89.2%, 57.1%, 184.6%, and 28.5% increase in fresh weight, dry weight, root length, and shoot length, respectively. NMDS analysis showed that the bacterial communities in river sand were more clustered after inoculation with PP4. These results indicated that the application of Pantoea sp. PP4 can facilitate the phytoremediation of Pb and Cd in oligotrophic growth substrates, forming a convergent bacterial community. Our findings highlighted the importance of identifying ideal PSB to improve phytoremediation efficiency in oligotrophic environments.

A novel exopolysaccharide from marine bacterium Pantoea sp. YU16-S3 accelerates cutaneous wound healing through Wnt/ß-catenin pathway.

Natural polysaccharides with versatile properties are the potential candidates for wound healing applications. In this study, an exopolysaccharide, EPS-S3, isolated from a marine bacteria Pantoea sp. YU16-S3 was evaluated for its wound-healing abilities by studying the key molecular mechanisms in vitro and in vivo. Basic characterisation showed EPS-S3 as a heteropolysaccharide with glucose, galactose, N-acetyl galactosamine and glucosamine. The molecular weight of EPS-S3 was estimated to be 1.75 × 105 Da. It showed thermal stability up to 200 °C and shear-thickening non-Newtonian behaviour. It was biocompatible with dermal fibroblasts and keratinocytes and showed cell adhesion and cell proliferation properties. EPS-S3 facilitated cell migration in fibroblasts, induced rapid transition of cell cycle phases and also activated macrophages. In vivo experiments in rats showed the re-epithelialization of injured tissue with increased expression of HB-EGF, FGF, E-cadherin and ß-catenin in EPS-S3 treatment. The results indicate that EPS-S3 modulates healing process through Wnt/ß-catenin pathway due to its unique characteristics. In conclusion, EPS-S3 biosynthesized by the marine bacterium is a potential biomolecule for cutaneous wound healing applications.

Identification and Characterization of the Phosphate-Solubilizing Bacterium Pantoea sp. S32 in Reclamation Soil in Shanxi, China.

Phosphate solubilizing bacteria (PSB) can convert insoluble forms of phosphorus (P) to accessible forms. Five highly efficient PSB strains, H22, Y11, Y14, Y34, and S32, were screened and isolated from an alfalfa rhizosphere in heavy metal-contaminated reclamation area in Shanxi Province, China. Based on morphological observations, 16S rRNA sequencing, cellular fatty acid composition analysis, and the BIOLOG test, H22, Y11, and Y34 were identified as Pseudomonas sp., while Y14 and S32 were identified as Pantoea sp. Among them, S32 showed the highest P-solubilizing efficiency in culture medium containing Ca3(PO4)2, lecithin, and powered phosphate rock. The culture medium conditions to obtain the highest P-solubilization efficiency were optimized as follows: the culture temperature was 30°C; the incubation time was 5 days; the initial pH was 7.0; and glucose served as the carbon source. Furthermore, the P-solubilization efficiency of S32 in media containing CaHPO4, lecithin, phosphate rock (PR), FePO4, or AlPO4 was determined to be 18.38, 3.07, 0.16, 0.51, or 2.62%, respectively. In addition, the acid and alkali phosphatase activities of S32 were tested as 6.94 U/100 mL and 4.12 U/100 mL, respectively. The soil inoculation experiment indicated that inoculation with S32 resulted in an obvious improvement in the available P of both the experimental and reclaimed soil. The rice seedling growth experiment also suggested that the application of S32 significantly increased the plant height, biomass, root growth, and P uptake of rice in both experimental and reclaimed soil. Taken together, the isolated S32 strain showed high P-solubilization capacity for both Pi and Po, and its ameliorative effect on reclaimed soil recovery provides the theoretical basis for crop development in the reclaimed soil of mine field.

Aflatoxin B1 removal by three bacterial strains and optimization of fermentation process parameters.

Aflatoxin B1 (AFB1 ) removing bacterial strains were isolated from different habitats that were easily contaminated by AFB1 . Furthermore, the composition of the fermentation medium and conditions of fermentation process were optimized, including carbon source, nitrogen source, metal ions, temperature, initial pH value, inoculation volume, and culture broth volume. Using coumarin as the sole carbon and energy source, we primarily screened 31 strains, and 10 strains were found to be capable to remove AFB1 . Among them, the highest removal rate of 71.91% appeared in those isolated from rotten wood (poplar). Strains XY1, XY3, and T6 were carried out to identify, and the results were Klebsiella sp., Klebsiella pneumonia, and Pantoea sp., respectively. Corn cob powder and tryptone can significantly increase the AFB1 removal activity of these strains. The AFB1 removal activity of Klebsiella sp.XY1 and K. pneumonia XY3 can be enhanced by Ca2+ , and those of Pantoea sp. T6 can be enhanced by Cu2+ . Temperature and initial pH were positively correlated with the AFB1 removal activity of these strains in a certain range. This study not only provides reference for the screening and application of AFB1 removing bacteria, but also provides a basis for possible application in the food and feed industry.

Development of a New Semi-Selective Lysine-Ornithine-Mannitol-Arginine-Charcoal Medium for the Isolation of Pantoea Species from Environmental Sources in Japan.

Although Pantoea species are widely distributed among plants, water, soils, humans, and animals, due to a lack of efficient isolation methods, the clonality of Pantoea species is poorly characterized. Therefore, we developed a new semi-selective medium designated 'lysine-ornithine-mannitol-arginine-charcoal' (LOMAC) to isolate these species. In an inclusive and exclusive study examining 94 bacterial strains, all Pantoea strains exhibited yellow colonies on LOMAC medium. The performance of the medium was assessed using Pantoea-spiked soils. Percent average agreement relative to the Api20E biochemical test was 97%. A total of 24 soil spot samples and 19 plant types were subjected to practical trials. Of the 91 yellow colonies selected on LOMAC medium, 81 were correctly identified as Pantoea species using the biochemical test. The sequencing of 16S rRNA (rrs) and gyrB from these isolates confirmed that Pantoea agglomerans, P. vagans, P. ananatis, and P. deleyi were present in Japanese fields. A phylogenetic analysis using rrs enabled only the limited separation of strains within each Pantoea spp., whereas an analysis using gyrB revealed higher variability and enabled the finer resolution of distinct branches. P. agglomerans isolates were divided into 3 groups, 2 of which were new clades, with the other comprising a large group including biocontrol strains. P. vagans was also in one of the new clades. The present results indicate that LOMAC medium is useful for screening Pantoea species. The use of LOMAC medium will provide new opportunities for identifying the beneficial properties of Japanese Pantoea isolates.

Purification and identification of an aflatoxin B1 degradation enzyme from Pantoea sp. T6.

Aflatoxin B1 (AFB1) is a secondary metabolite produced by Aspergillus flavus and other fungi. Soil, crops, food, feed, etc. were susceptible to aflatoxin B1 contamination, which caused adverse economic and health consequences. It is necessary to search for microorganisms or microbial enzymes that can degrade AFB1. The degradation activity of AFB1 by cell-free supernatant (68.30%) of isolate Pantoea sp. T6 was significantly higher (P < 0.05) than viable bacterial cells (4.87%) and intracellular cell extracts (3.68%). The supernatant's AFB1 degradation activity was reduced from 68.30% to 5.33% in treatment with protease K and sodium dodecyl sulphate (SDS). An extracellular enzyme from the supernatant was secreted by Pantoea sp. T6 and was named as Pantoea aflatoxin degradation enzyme (PADE), which was obtained using Diethylaminoethanol (DEAE)-Sepharose chromatography. PADE was further purified by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The PADE, outer membrane protein A, was identified by mass spectrometry and molecular mass was 38180.1Da. The optimum temperature and pH for the reaction of PADE with AFB1 were 40 °C and 7.0, respectively. These finding showing that the PADE, which was isolated from the supernatant of Pantoea sp. T6, has the ability to degrade AFB1, and may have potential application for aflatoxin B1 reduction in the food and feed industry.

Exopolysaccharide from Pantoea sp. BCCS 001 GH isolated from nectarine fruit: production in submerged culture and preliminary physicochemical characterizations.

Exopolysaccharide (EPS), as potential microbial base polysaccharide source, has plenty of applications due to its unique physicochemical structure. A Pantoea sp. BCCS 001 GH bacterium with the ability to produce a high amount of EPS was identified by 16S rRNA gene sequencing and biochemical tests. The synthesis of EPS by Pantoea sp. BCCS 001 GH was 13.50 g/L in 48 h when sucrose was used as substrate. The proposed protocol was desirably rapid for massive prodcution of EPS and showed the remarkable impact of sucrose and disodium hydrogen phosphate, peptone, Triton x-100 and 2% (v/v) inoculum size on the yields of EPS production. The EPS was mainly composed of glucose and galactose in a relative molar ration (glucose/galactose) of 85.18:14.82, respectively. The preliminary characterization showed the average molecular-weight of EPS is about 2.522 × 106 Da. The microscopics morphology of polymer was formed irregularly shaped structures.

Eexopolysaccharide production of Pantoea sp. BCCS 001 GH: Physical characterizations, emulsification, and antioxidant activities.

The newly discovered exopolysaccharide (EPS) produced by Pantoea sp. BCCS 001 GH, isolated from nectarine fruit and some of its physical properties were characterized. This paper examines precipitation, rheological behavior, emulsification, and antioxidant activities of EPS. Particularly, the concentration of common salt (NaCl) affected on precipitation of EPS; while the low ratio (3 Vagent/V) of CaCl2 isopropanol to culture broth was required. The Zeta potential value of emulsified particles had a high surface charge -65.67 ±â€¯0.6 mV. The strong hydrogen bonds and/or hydrophobic interactions between the polysaccharide and the Congo red molecule showed the triple helical polysaccharide. The water solubility index and water holding capacity of the EPS were 15.6 ±â€¯0.22, 662 ±â€¯12.5%, respectively. The degradation temperature (Td) of 318 °C was observed from the TGA curve for the EPS. The rheological study indicated that the EPS had typically non-Newtonian pseudoplastic behavior. Among the EPS and Tween 80 tested against oils/hydrocarbons, EPS was found to be one the most effective emulsifying agent against kerosene, xylene, hexane and diesel (72.8, 74.5, 68.3 and 81.1%, respectively). It was found that changes in pH (2-12) significantly influenced the emulsification of kerosene and diesel. In vitro antioxidant activity of EPS against hydroxyl, 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH), and superoxide free radicals shown good antioxidant activities. These results indicate the favorable potential of the EPS from strain BCCS 001 GH in food and pharmaceutical fields.

Accumulation of U(VI) on the Pantoea sp. TW18 isolated from radionuclide-contaminated soils.

Pantoea sp. TW18 isolated from radionuclide-contaminated soils was used for the bioremediation of radionuclides pollution. Accumulation mechanism of U(VI) on Pantoea sp. TW18 was investigated by batch experiments and characterization techniques. The batch experiments revealed that Pantoea sp. TW18 rapidly reached accumulation equilibrium at approximately 4 h with a high accumulation capacity (79.87 mg g-1 at pH 4.1 and T = 310 K) for U(VI). The accumulation data of U(VI) onto Pantoea sp. TW18 can be satisfactorily fitted by pseudo-second-order model. The accumulation of U(VI) on Pantoea sp. TW18 was affected by pH levels, not independent of ionic strength. Analysis of the FT-IR and XPS spectra demonstrated that accumulated U(VI) ions were primarily bound to nitrogen- and oxygen-containing functional groups (i.e., carboxyl, amide and phosphoryl groups) on the Pantoea sp. TW18 surface. This study showed that Pantoea sp. TW18 can be considered as a promising sorbent for remediation of radionuclides in environmental cleanup.

Improvement of Glyphosate Resistance through Concurrent Mutations in Three Amino Acids of the Pantoea sp. 5-Enolpyruvylshikimate-3-Phosphate Synthase.

Glyphosate inhibits the target enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) in the shikimate pathway. A mutant of EPSPS from Pantoea sp. was identified using site-directed mutagenesis (SDM). The mutant significantly improved glyphosate resistance. The mutant had mutations in three amino acids: Gly97 to Ala, Thr 98 to Ile and Pro 102 to Ser. These mutation sites in E.coli have been studied as significant active sites of glyphosate resistance. However, in our research they were found to jointly contribute to the improvement of glyphosate tolerance. In addition, the level of glyphosate tolerance in transgenic Arabidopsis confirmed the potentiality of the mutant in breeding glyphosate-resistant plants.

Characterization of Indole-3-acetic Acid Biosynthesis and the Effects of This Phytohormone on the Proteome of the Plant-Associated Microbe Pantoea sp. YR343.

Indole-3-acetic acid (IAA) plays a central role in plant growth and development, and many plant-associated microbes produce IAA using tryptophan as the precursor. Using genomic analyses, we predicted that Pantoea sp. YR343, a microbe isolated from Populus deltoides, synthesizes IAA using the indole-3-pyruvate (IPA) pathway. To better understand IAA biosynthesis and the effects of IAA exposure on cell physiology, we characterized proteomes of Pantoea sp. YR343 grown in the presence of tryptophan or IAA. Exposure to IAA resulted in upregulation of proteins predicted to function in carbohydrate and amino acid transport and exopolysaccharide (EPS) biosynthesis. Metabolite profiles of wild-type cells showed the production of IPA, IAA, and tryptophol, consistent with an active IPA pathway. Finally, we constructed an Δ ipdC mutant that showed the elimination of tryptophol, consistent with a loss of IpdC activity, but was still able to produce IAA (20% of wild-type levels). Although we failed to detect intermediates from other known IAA biosynthetic pathways, this result suggests the possibility of an alternate pathway or the production of IAA by a nonenzymatic route in Pantoea sp. YR343. The Δ ipdC mutant was able to efficiently colonize poplar, suggesting that an active IPA pathway is not required for plant association.

[Redox Transformation of Arsenic and Antimony in Soils Mediated by Pantoea sp. IMH].

Soil contamination with co-existing arsenic (As) and antimony (Sb) has become a serious environmental problem worldwide. Microorganisms play a dominant role in the redox transformation and mobilization of As and Sb. As and Sb belong to the same family; they are alike in nature and have related microbial oxidation-reduction mechanisms. However, limited knowledge is available about the impact of As-reducing bacteria on the fate of As and Sb in their co-existing soils. The purpose of this study was to explore the redox transformation and release of As and Sb in the presence of an arsC carrier, Pantoea sp. IMH, which has high As(Ⅴ)-reducing capability. In addition to the IMH incubation system, the dead cell system and abiotic control experiments were conducted. The results showed that the IMH incubation reduced all soluble As(Ⅴ) (72.7 µg·L-1) to As(Ⅲ) form, whereas soluble Sb(Ⅴ) (364.8 µg·L-1) was not reduced, indicating that the As (V)-reducing pathway mediated by arsC genesis was not able to reduce Sb(Ⅴ). The amounts of total As (506.8 µg·L-1) and total Sb (821.1 µg·L-1) in the dead cell system were approximately four times higher than in the living cell system (As=155.2 µg·L-1; Sb=364.8 µg·L-1) and the abiotic control (As=57.6 µg·L-1; Sb=271.1 µg·L-1) because of the biomolecules released from the dead cells which enhanced the release of As and Sb. The correlation analysis of dissolved As and Sb showed that the release of total As and Sb was correlated (P<0.05) in three systems. Our study shed new light on the impact of bacteria on the fate of As and Sb in soils.

Novel bacterial consortia isolated from plastic garbage processing areas demonstrated enhanced degradation for low density polyethylene.

This study aimed to formulate novel microbial consortia isolated from plastic garbage processing areas and thereby devise an eco-friendly approach for enhanced degradation of low-density polyethylene (LDPE). The LDPE degrading bacteria were screened and microbiologically characterized. The best isolates were formulated as bacterial consortia, and degradation efficiency was compared with the consortia formulated using known isolates obtained from the Microbial Culture Collection Centre (MTCC). The degradation products were analyzed by FTIR, GC-FID, tensile strength, and SEM. The bacterial consortia were characterized by 16S ribosomal DNA (rDNA) sequencing. The formulated bacterial consortia demonstrated 81 ± 4 and 38 ± 3 % of weight reduction for LDPE strips and LDPE pellets, respectively, over a period of 120 days. However, the consortia formulated by MTCC strains demonstrated 49 ± 4 and 20 ± 2 % of weight reduction for LDPE strips and pellets, respectively, for the same period. Furthermore, the three isolates in its individual application exhibited 70 ± 4, 68 ± 4, and 64 ± 4 % weight reduction for LDPE strips and 21 ± 2, 28 ± 2, 24 ± 2 % weight reduction for LDPE pellets over a period of 120 days (p < 0.05). The end product analysis showed structural changes and formation of bacterial film on degraded LDPE strips. The 16S rDNA characterization of bacterial consortia revealed that these organisms were novel strains and designated as Enterobacter sp. bengaluru-btdsce01, Enterobacter sp. bengaluru-btdsce02, and Pantoea sp. bengaluru-btdsce03. The current study thus suggests that industrial scale-up of these microbial consortia probably provides better insights for waste management of LDPE and similar types of plastic garbage.

Lotus japonicus plants of the Gifu B-129 ecotype subjected to alkaline stress improve their Fe(2+) bio-availability through inoculation with Pantoea eucalypti M91.

Inoculation assays with Pantoea eucalypti M91 were performed on Lotus japonicus ecotype Gifu. Under alkaline conditions, this ecotype is characterized by the development of interveinal chlorosis of the apical leaves due to low mobilization of Fe(2+). Inoculation with P. eucalypti M91, a plant growth-promoting bacterial strain capable of producing pyoverdine-like and pyochelin-like siderophores under alkaline growth conditions, alters the root, resulting in a herringbone pattern of root branching. Additional features include improvement in Fe(2+) transport to the shoots, acidification of the hydroponic solution of the plant cultures, and an accompanying increase in the efficiency of the PSII parameters. In addition, there was an increase in the expression of the FRO1 and IRT1 genes, accompanied by a significant increase in FRO activity. Results showed that P. eucalypti M91 has a beneficial effect on the Fe acquisition machinery of Strategy I, as described for non-graminaceous monocots and dicots, suggesting its potential as an inoculant for legume crops cultivated in alkaline soils.

[Screening, identification and phosphate-solubilizing characteristics of phosphate-solubilizing bacteria strain D2 (Pantoea sp.)in rhizosphere of Pinus tabuliformis in iron tailings yard.] / é“å°¾çŸ¿åŒºæ²¹æ¾æ ¹é™ æº¶ç£·æ³›èŒD2的筛选鉴定及溶磷特性.

Two strains of phosphate-solubilizing bacteria were isolated from the rhizosphere of Pinus tabuliformis in iron tailings vegetation restoration areas in Malan Town, Qianan City, Hebei Pro-vince. The bacterial strain D2 with strong phosphate-solubilizing capacity was obtained via screening with plate and shake flask. Based on the morphology, physiology and biochemistry, and the sequence analysis of 16S rDNA, the D2 was identified as a member of Pantoea sp. A fermentation experiment was conducted to investigate the effect of carbon and nitrogen sources on the phosphate-solubilizing capacity of the strain D2; under different nitrogen sources, the organic acids in liquid culture, as well as their types and contents were determined by high performance liquid chromatography. The results showed that the strain D2 was capable of efficiently solubilizing tricalcium phosphate, and the highest value of available phosphorus was up to 392.13 mg·L-1 in liquid culture. The strain D2 displayed the strongest phosphate-solubilizing capability when glucose and ammonium sulfate were used as carbon and nitrogen sources in the culture media, respectively. Under varied nitrogen sources, the resulting organic acids and their types and contents were different. When the nitrogen source in culture media was ammonium sulfate, ammonium chloride, potassium nitrate, sodium nitrate or ammonium nitrate, all four organic acids, including oxalic acid, formic acid, acetic acid and citric acid, were produced. In addition, malic acid was uniquely produced when ammonium sulfate, ammonium chloride or ammonium nitrate was used as the nitrogen source. By Pearson's correlation analysis, a significant positive correlation between the acetic acid content and the available phosphorus content was found (r=0.886, P<0.05), suggesting that acetic acid produced by strain D2 played an important role in promoting inorganic phosphorus dissolution, which was most likely to be one of the important phosphate-solubilizing mechanisms of the strain.

Efecto de un bioinoculante a partir de consorcios microbianos nativos fosfato solubilizadores, en el desarrollo de pastos Angleton (Dichantium aristatum) / Effect of bio-inoculant from microbial consortia phosphate solubilizing natives in development of pastures (Dichantium aristatum)

El objetivo fue evaluar la capacidad solubilizadora de fosfatos de consorcios formados por bacterias nativas de los géneros Burkholderia cepacia, Pseudomonas sp, Pseudomonas luteola y Pantoea sp, con el fin de encontrar el más eficiente. Se realizaron pruebas de antagonismo entre las cepas y se formaron consorcios probando todas las combinaciones posibles en las concentraciones de 10(6), 10(7), 10(8) UFC/mL. Se realizaron evaluaciones cualitativas y cuantitativas de la solubilización de fosfatos y teniendo en cuenta éstos resultados, se preparó un bioinoculante el cual fue evaluado en semillas de plantas de pasto angleton (Dichantium aristatum) a escala de laboratorio, utilizando un diseño estadístico completamente al azar (DCA) con 3 tratamientos y 5 repeticiones: Tratamiento 1 semillas (control), Tratamiento 2, semillas tratadas con el consorcio de microorganismos seleccionado y Tratamiento 3, semillas tratadas con fertilizantes comerciales DAP y Urea. Se evaluaron las variables número de hojas, área foliar, longitud de la planta, longitud de la raíz y peso seco de todas las plantas. Los resultados de la prueba de antagonismo indicaron que no existe inhibición en el crecimiento de las cepas evaluadas, por lo tanto se formaron consorcios los cuales mostraron mayor eficiencia en la solubilización del fósforo, destacándose el consorcio formado por Pantoea sp + Pseudomonas sp a una concentración de 10(8) UFC/mL y con índices de solubilización de 5,3 y 842 ppm. En las plantas se evidenció un incremento significativo en los parámetros peso seco y área foliar usando el consorcio microbiano, indicando mayor beneficio en comparación con el control.

The objective was to evaluate the ability of phosphate solubilizing consortium of native bacteria of the genusBurkholderia cepacia, Pseudomonas sp, Pseudomonas luteola and Pantoea sp, in order to find the most efficient. Antagonism tests were conducted between strains and consortia were formed using all possible combinations in the concentrations of 10(6), 10(7), 10(8) CFU / mL. Qualitative and quantitative determinations of the solubilization of phosphates were performed and considering these results, was prepared a bio-inoculant which was evaluated in plant seeds of grass angleton (Dichantium aristatum) laboratory scale, using a statistical completely randomized design (CRD) with 3 treatments and 5 repetitions: control Treatment 1 seeds; Treatment 2, seeds treated with the consortium of microorganisms selected and Treatment 3, seeds treated with commercial fertilizers DAP and Urea. The parameters, number of leaves, leaf area, plant length, root length and dry weights of all plants, were evaluated. The test results indicated that there is no antagonism inhibition in the growth of the strains tested thus formed consortia which showed greater efficiency phosphorus solubilization, highlighting the consortium of Pantoea sp + Pseudomonas sp at a concentration 10(8)CFU / mL and 5.3 solubilization rates and 842 ppm. In plants showed a significant increase in dry weight and leaf area parameters, indicating greater benefit with respect to the control treatment.

Isolation of a rice endophytic bacterium, Pantoea sp. Sd-1, with ligninolytic activity and characterization of its rice straw degradation ability.

UNLABELLED: This study focused on an endophytic bacterial strain, Pantoea sp. Sd-1, which can be used to degrade lignin and rice straw. This strain was isolated from rice seeds by an optimized surface sterilization method. Pantoea sp. Sd-1 showed exceptional ability to degrade rice straw and lignin. In rice straw or kraft lignin-containing medium supplemented with 1% glucose and 0.5% peptone, Pantoea sp. Sd-1 effectively reduced the rice straw mass weight by 54.5% after 6 days of treatment. The strain was also capable of reducing the lignin colour (52.4%) and content (69.1%) after 4 days of incubation. The findings suggested that the rice endophytic bacterium Pantoea sp. Sd-1 could be applied for the degradation of lignocellulose biomass, such as rice straw. SIGNIFICANCE AND IMPACT OF THE STUDY: Rice straw, an abundant agricultural by-product in China, is very difficult to degrade because of its high lignin content. Due to the immense environmental adaptability and biochemical versatility of bacteria, endophytic bacteria are useful resources for biodegradation. In this study, we screened for endophytic bacteria capable of biodegrading rice straw and lignin and obtained one strain, Pantoea sp. Sd-1, with suitable characteristics. Sd-1 could be used for degradation of rice straw and lignin, and may play an important role in biodegradation of this agricultural by-product.