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Copyright of Revista Colombiana de Gastroenterología is the property of Asociacion Colombiana de Gastroenterologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The oil industry has generated chronic oil spills and their accumulation in wetlands of the state of Tabasco, in Southeastern Mexico. Waterlogging is a factor that limits the use of remediation technologies because of its high cost and low levels of oil degradation. However, Leersia hexandra is a grass that grows in these contaminated areas with weathered oil. The aim of the study was to evaluate the bacteria density, plant biomass production and phytoremediation of L. hexandra in contaminated soil. For this, two experiments in plastic tunnel were performed with fresh (E1) and weathered petroleum (E2) under waterlogging experimental conditions. The E1 was based on eight doses: 6 000, 10 000, 30 000, 60 000, 90 000, 120 000, 150 000 and 180 000 mg.kg-1 dry basis (d. b.) of total petroleum hydrocarbons fresh (TPH-F), and the E2, that evaluated five doses: 14 173, 28 400, 50 598, 75 492 and 112 142 mg. kg-1 d. b. of total petroleum hydrocarbons weathered (TPH-W); a control treatment with 2 607 mg.kg-1 d. b. was used. Each experiment, with eight replicates per treatment, evaluated after three and six months: a) microbial density of total free-living nitrogen-fixing bacteria (NFB) of Azospirillum (AZP) and Azotobacter group (AZT), for viable count in serial plate; b) dry matter production (DMP), quantified gravimetrically as dry weight of L. hexandra; and c) the decontamination percentage of hydrocarbons (PDH) by Soxhlet extraction. In soil with TPH-F, the NFB, AZP y AZT populations were stimulated five times more than the control both at the three and six months; however, concentrations of 150 000 and 180 000 mg.kg-1 d. b. inhibited the bacterial density between 70 and 89 %. Likewise, in soil with TPH-W, the FNB, AZP and AZT inhibitions were 90 %, with the exception of the 14 173 mg.kg-1 d. b. treatment, which stimulated the NFB and AZT in 2 and 0.10 times more than the control, respectively. The DMP was continued at the six months in the experiments, with values of 63 and 89 g in fresh and weathered petroleum, respectively; had no significant differences with the control (p≤0.05). The PDH reached values of 66 to 87 % both TPH-F and TPH-W at six months, respectively. These results demonstrated the ability the L. hexandra rhizosphere to stimulate the high NFB density, vegetal biomass production and phytoremediation of contaminated soils (with fresh and weathered petroleum), in a tropical waterlogging environment. Rev. Biol. Trop. 65 (1): 21-30. Epub 2017 March 01. [ABSTRACT FROM AUTHOR]

The effect of different types and doses of organic fertilisers (OF) on the chemical properties of the soil (organic C, total N and available P), the density of bacteria that regulate plant growth Azospirillum, Azotobacter, P-solubilising bacteria and K-solubilising bacteria in soil at a distance and rhizosphere, arbuscular mycorrhizal colonisation (hyphae, arbuscules and vesicles) and hybrid plant growth of Citrange troyer [height and basal stem diameter at five time intervals; dry foliar matter (DFM) and dry root matter (DRM)] was evaluated 11 months after transplantation in the nursery. There were 14 treatments, 12 with types of OF [chicken manure (CM), sugarcane residue-1 (SR1), sugarcane residue-2 (SR2) and banana waste (BW)] and doses (1, 2 and 3 %), that were compared with two controls (one with urea and one absolute). The results show statistically significant differences (Tukey, p ≤ 0.05) due to the effect of the type and dose of OF on all the chemical and microbiological parameters, and on the growth of C. troyer. The rhizosphere effect was observed in most treatments with OF. The use of CM at a dose of 2 % stimulates plant growth and at a dose of 3 % favours an increase in basal stem diameter, DFM, DRM and the DFM / DRM relationship. It was found that DFM and DRM have a highly signi_cant relationship with the content of N in the soil, the densities of P-solubilising bacteria and Azospirillum, and the colonisation of the root by mycorrhizal structures of hyphae, arbuscules and vesicles. Thus, the use of CM is recommended at doses of 2 and 3 % to obtain C. troyer plants in nurseries. [ABSTRACT FROM AUTHOR]

Introduction: Plants and microorganisms have been used as bioindicators to evaluate the toxicity of hydrocarbons in soils. Objective: This study evaluates the toxicity of a chronically-contaminated Gleysol with several concentrations of weathered petroleum hydrocarbons (WPH), collected from La Venta, Tabasco (Mexico), on the growth of Clitoria ternatea and the phytoxicity attenuation due to inoculation of emulsifying bacteria. Methods: Soils with 50 and 150 g WPH kg-1, and control soil with 0.15 g WPH kg-1 (biogenic origin) were utilized, as well as the inoculation of six emulsifying bacteria and their combination (consortium). The WPH-phytotoxicity was evaluated by considering plant height, dry biomass production (root, shoot, and total), leaf area, specific leaf area, and the efficiency of photosystem II (EPSII), after 30 days. Results: WPH did not affect plant height, but soil with 50 g WPH kg-1 diminished root and total dry weight, and leaf area, when compared to both control soil and soil with 150 g WPH kg-1. The strain Sml (Stenotrophomonas maltophilia C10S1) significantly increased shoot and total dry weight, while the strain Ro (Raoultella ornithinolytica C5S3) produced higher specific leaf area relative to uninoculated plants. In control soil, the bacterial consortium stimulated plant height. The strains Sm (Serratia marcescens C11S1) and Sm2 (S. marcescens C7S3) improved plant height and specific leaf area when compared to uninoculated plants in soil with 50 g WPH kg-1. In soil with 150 g WPH kg-1, strains Spa (Stenotrophomonas pavanii C5S3F) and Cfr (Citrobacter freundii C4S3) enhanced root and shoot dry weight, respectively. The EPSII was unaffected by soil contamination. Emulsifying bacteria reduced the phytotoxic effects of WP, but depending on the content of WPH in soils. Conclusions: Soil with 50 g WPH kg-1 showed the greatest phytotoxic effects on plant growth. Bacterial inoculation favored growth, biomass production and leaf area in soil with 150 g WPH kg-1. The EPSII was not affected by WPH in soils. [ABSTRACT FROM AUTHOR]

A disease of the roselle (Hibiscus sabdariffa) of unknown etiology epidemically appeared in Tabasco, Mexico, during 2008-2009 with more than 70% incidence. The diseased plants were characterized by circular and irregularly shaped, light brown colored spots on leaves, necrotic lesions with water-like appearance extended to the entire leaf blade and petiole. The leaf spots initiated from the lower leaves and advanced to higher foliage, resulting in full defoliation and yield losses. Through postulates from Koch, the colony's morphology and DNA sequencing, it was concluded that the causal agent corresponds to the fungus Pilidiella diplodiella fungus (syn. Phoma diplodiella). This is the first report of P. diplodiella causing a disease in roselle, that in the present study has been referred to as watery spot due to the water-like appearance in one of its stages of development. [ABSTRACT FROM AUTHOR]