Transcriptional and Metabolic Response of a Strain of Escherichia coli PTS- to a Perturbation of the Energetic Level by Modification of [ATP]/[ADP] Ratio.

The intracellular [ATP]/[ADP] ratio is crucial for Escherichia coli's cellular functions, impacting transport, phosphorylation, signaling, and stress responses. Overexpression of F1-ATPase genes in E. coli increases glucose consumption, lowers energy levels, and triggers transcriptional responses in central carbon metabolism genes, particularly glycolytic ones, enhancing carbon flux. In this contribution, we report the impact of the perturbation of the energetic level in a PTS- mutant of E. coli by modifying the [ATP]/[ADP] ratio by uncoupling the cytoplasmic activity of the F1 subunit of the ATP synthase. The disruption of [ATP]/[ADP] ratio in the evolved strain of E. coli PB12 (PTS-) was achieved by the expression of the atpAGD operon encoding the soluble portion of ATP synthase F1-ATPase (strain PB12AGD+). The analysis of the physiological and metabolic response of the PTS- strain to the ATP disruption was determined using RT-qPCR of 96 genes involved in glucose and acetate transport, glycolysis and gluconeogenesis, pentose phosphate pathway (PPP), TCA cycle and glyoxylate shunt, several anaplerotic, respiratory chain, and fermentative pathways genes, sigma factors, and global regulators. The apt mutant exhibited reduced growth despite increased glucose transport due to decreased energy levels. It heightened stress response capabilities under glucose-induced energetic starvation, suggesting that the carbon flux from glycolysis is distributed toward the pentose phosphate and the Entner-Duodoroff pathway with the concomitant. Increase acetate transport, production, and utilization in response to the reduction in the [ATP]/[ADP] ratio. Upregulation of several genes encoding the TCA cycle and the glyoxylate shunt as several respiratory genes indicates increased respiratory capabilities, coupled possibly with increased availability of electron donor compounds from the TCA cycle, as this mutant increased respiratory capability by 240% more than in the PB12. The reduction in the intracellular concentration of cAMP in the atp mutant resulted in a reduced number of upregulated genes compared to PB12, suggesting that the mutant remains a robust genetic background despite the severe disruption in its energetic level.

Safety of biologic therapy in combination with methotrexate in moderate to severe psoriasis: a cohort study from the BIOBADADERM registry.

BACKGROUND: Safety is an important consideration in decisions on treatment for patients with moderate-to-severe psoriasis and the study of drug safety is the main purpose of the BIOBADADERM registry. The combination of a biologic agent and a conventional systemic drug [generally methotrexate (MTX)] is a common treatment in clinical practice. However, there is a paucity of evidence from real-world practice on the safety of such combination regimens in the treatment of psoriasis. OBJECTIVES: The primary objective of this study was to ascertain whether the use of regimens combining biologic drugs with MTX in the management of moderate-to-severe psoriasis increases the risk of adverse events (AEs) or serious AEs (SAEs). We compared monotherapy using tumour necrosis factor (TNF), interleukin (IL)-17 and IL-23 inhibitors with the use of the same drugs in combination with MTX. METHODS: Using data from the BIOBADADERM registry, we compared biologic monotherapies with therapies that were combined with MTX. We estimated adjusted incidence rate ratios (aIRR) using a random effects Poisson regression with 95% confidence intervals for all AEs, SAEs, infections and serious infections and other AEs by system organ class. RESULTS: We analysed data from 2829 patients and 5441 treatment cycles, a total of 12 853 patient-years. The combination of a biologic with MTX was not associated with statistically significant increases in overall risk of AEs or SAEs in any treatment group. No increase in the total number of infections or serious infections in patients receiving combined therapy was observed for any group. However, treatment with a TNF inhibitor combined with MTX was associated with an increase in the incidence of gastrointestinal AEs (aIRR 2.50, 95% CI 1.57-3.98; P < 0.002). CONCLUSIONS: The risk of AEs and SAEs was not significantly increased in patients with moderate-to-severe psoriasis receiving different classes of biologic drugs combined with MTX compared with those on biologic monotherapy.

Glucose Transport in Escherichia coli: From Basics to Transport Engineering.

Escherichia coli is the best-known model for the biotechnological production of many biotechnological products, including housekeeping and heterologous primary and secondary metabolites and recombinant proteins, and is an efficient biofactory model to produce biofuels to nanomaterials. Glucose is the primary substrate used as the carbon source for laboratory and industrial cultivation of E. coli for production purposes. Efficient growth and associated production and yield of desired products depend on the efficient sugar transport capabilities, sugar catabolism through the central carbon catabolism, and the efficient carbon flux through specific biosynthetic pathways. The genome of E. coli MG1655 is 4,641,642 bp, corresponding to 4702 genes encoding 4328 proteins. The EcoCyc database describes 532 transport reactions, 480 transporters, and 97 proteins involved in sugar transport. Nevertheless, due to the high number of sugar transporters, E. coli uses preferentially few systems to grow in glucose as the sole carbon source. E. coli nonspecifically transports glucose from the extracellular medium into the periplasmic space through the outer membrane porins. Once in periplasmic space, glucose is transported into the cytoplasm by several systems, including the phosphoenolpyruvate-dependent phosphotransferase system (PTS), the ATP-dependent cassette (ABC) transporters, and the major facilitator (MFS) superfamily proton symporters. In this contribution, we review the structures and mechanisms of the E. coli central glucose transport systems, including the regulatory circuits recruiting the specific use of these transport systems under specific growing conditions. Finally, we describe several successful examples of transport engineering, including introducing heterologous and non-sugar transport systems for producing several valuable metabolites.

Anti-interleukin-17 therapies for moderate/severe psoriasis in clinical practice: effectiveness, safety and association with clinical patient factors.

OBJECTIVES: Interleukin-17 (IL-17) contributes to the pathogenesis of psoriasis. Secukinumab, ixekizumab, and brodalumab are monoclonal antibodies anti-IL-17 antibodies, approved for the treatment of moderate/severe plaque psoriasis.The aim of the study was to describe the effectiveness and safety of anti-IL-17 agents in moderate/severe plaque psoriasis in clinical practice. We also analysed anti-IL-17 therapies' survival, dose adjustment, and clinical patients' factors associated with their effectiveness and safety. METHODS: A retrospective, longitudinal study was conducted at a tertiary hospital. We included patients with moderate/severe psoriasis treated with anti-IL-17 agents. The effectiveness was evaluated with Psoriasis Area and Severity Index (PASI) score and safety through the adverse drug reactions (ADRs) collected. RESULTS: 38 patients were studied (median age=47.4 years, 71.0% male). The mean number of biological therapies that patients received was 2.6, and anti-IL-17 therapy was the first biological therapy for 36.8% of patients. The median years in treatment were 2.5 (95% CI 1.95 to 2.98) for secukinumab, 1.2 (95% CI 0.36 to 1.47) for ixekizumab, and 0.7 (IQR 0.71) for brodalumab. The median PASI score after 6 months of treatment was 0 (IQR 0) and 85.3% of patients achieved a PASI of 90 (84.0% with secukinumab, 87.5% with ixekizumab, and 100% with brodalumab). Dose adjustment was associated with the line of treatment (p=0.034 for naïve patients), age (p=0.044 for younger patients), and concomitant pathologies (p=0.015 without more diseases).24 patients suffered from ADRs, mainly infections of the upper respiratory tract, and there were no statistically significant differences between the three therapies. CONCLUSIONS: Anti-IL-17 agents constitute an effective treatment for patients with moderate/severe plaque psoriasis and for longer. Dose reductions were associated with fewer lines of treatment, younger patients and absence of concomitant pathologies. ADR were minor and similar among the anti-IL-17.

Screening of Phosphate Solubilization Identifies Six Pseudomonas Species with Contrasting Phytostimulation Properties in Arabidopsis Seedlings.

The interaction of plants with bacteria and the long-term success of their adaptation to challenging environments depend upon critical traits that include nutrient solubilization, remodeling of root architecture, and modulation of host hormonal status. To examine whether bacterial promotion of phosphate solubilization, root branching and the host auxin response may account for plant growth, we isolated and characterized ten bacterial strains based on their high capability to solubilize calcium phosphate. All strains could be grouped into six Pseudomonas species, namely P. brassicae, P. baetica, P. laurylsulfatiphila, P. chlororaphis, P. lurida, and P. extremorientalis via 16S rRNA molecular analyses. A Solibacillus isronensis strain was also identified, which remained neutral when interacting with Arabidopsis roots, and thus could be used as inoculation control. The interaction of Arabidopsis seedlings with bacterial streaks from pure cultures in vitro indicated that their phytostimulation properties largely differ, since P. brassicae and P. laurylsulfatiphila strongly increased shoot and root biomass, whereas the other species did not. Most bacterial isolates, except P. chlororaphis promoted lateral root formation, and P. lurida and P. chlororaphis strongly enhanced expression of the auxin-inducible gene construct DR5:GUS in roots, but the most bioactive probiotic bacterium P. brassicae could not enhance the auxin response. Inoculation with P. brassicae and P. lurida improved shoot and root growth in medium supplemented with calcium phosphate as the sole Pi source. Collectively, our data indicate the differential responses of Arabidopsis seedlings to inoculation with several Pseudomonas species and highlight the potential of P. brassicae to manage phosphate nutrition and plant growth in a more eco-friendly manner.

Secukinumab is effective and safe in the long-term treatment of plaque psoriasis in a daily practice setting: Multicenter study in 384 Spanish patients.

The aim of the study was to assess the long-term effectiveness and safety of secukinumab in Spanish patients with moderate-to-severe psoriasis in a daily practice setting. Nationwide multicenter, observational, retrospective, non-interventional, single-cohort study including patients who initiated treatment with secukinumab in daily clinical practice conditions. Subjects were followed for a minimum of 3 months and a maximum of 24 months. Psoriasis Area Severity Index (PASI), Body Surface Area and Physician's Global Assessments were collected at baseline and months 3, 6, 12, 18 and 24 during treatment. Adverse events and reasons for secukinumab withdrawal were collected and classified for analyses. A total of 384 patients were enrolled in the study. Median PASI declined rapidly from 14.3 at baseline to 2.7 at month 3, 2.1 at month 12, and remained low (2.8) at month 24. Within the group of patients with PASI ≥10 at baseline (n = 278), 58.3%, 60.4% and 56.5% achieved a PASI90 response at months 3, 12 and 24, respectively. As for absolute PASI, 86.5%, 69.5%, 42.7% and 37% achieved PASI <5, < 3, < 1 and 0, respectively, at month 3. Secukinumab was more effective in biologic-naïve patients and in those with lower Body Mass Index. Secukinumab presented a good long-term safety profile. Secukinumab was effective and safe in a routine clinical setting, in a large cohort of patients with moderate-to-severe plaque psoriasis, in the short-, medium- and long-term (up to 24 months).

Fast and sustained improvement of patient-reported outcomes in psoriatic patients treated with secukinumab in a daily practice setting.

Psoriasis is a chronic dermatological disease with great impact on patients' quality of life (QoL). The main objective of this study was to assess the impact of secukinumab treatment on different patient-reported outcomes (PROs) during a long-term follow-up in Spanish patients with moderate-to-severe psoriasis under real-world conditions. Retrospective, observational, open-label, nationwide multicenter cohort study that included patients who initiated treatment with secukinumab in daily clinical practice conditions. PROs assessing disease impact and QoL included Dermatology Life Quality Index (DLQI), Patient's Global Psoriasis Assessment, Itch Numerical Rating Scale and EuroQoL Thermometer Visual Analogue Scale. Outcomes, including PROs and Psoriasis Area and Severity Index (PASI), were assessed at months 3, 6, 12, 18, and 24 during treatment. A total of 238 patients were enrolled in the study. Patients had a mean DLQI score of 14.9 at baseline; 78.3%, 73.7%, and 71.7% of them achieved a DLQI 0/1 response at months 6, 12, and 24, respectively. DLQI score was lower in the long term for naïve patients. A sharp decrease in mean DLQI was observed during the first 3 months, reaching a plateau that was maintained until the end of follow-up. Similar findings were observed for the rest of QoL assessments. There was a close association between improvement in QoL and skin clearance (PASI), which progressively increased during follow-up. In this study, secukinumab sustainably improved patient's QoL during a 24-month follow-up, with strongest effects in patients naïve to biological therapies and with a direct correlation with PASI improvement.

The risk of hepatic adverse events of systemic medications for psoriasis: a prospective cohort study using the BIOBADADERM registry.

BACKGROUND: Limited information is available regarding the risk of incident liver disease in patients with psoriasis receiving systemic therapies. OBJECTIVES: To describe the liver safety findings of conventional and modern systemic therapies for moderate-to-severe psoriasis, and to compare the relative incidence rates of hepatic adverse events (AEs) for each drug. METHODS: All the patients on the BIOBADADERM registry were included. Crude and adjusted incidence rate ratios (cIRR and aIRR, respectively) of hepatic AEs, using anti-TNF drugs as reference, were determined. Outcomes of interest were hypertransaminasemia, nonalcoholic fatty liver disease (NADFLD) and a group of other, less represented, hepatic AEs. RESULTS: Our study included 3,171 patients exposed to systemic drugs (6279 treatment cycles). Incident hypertransaminasemia was the most frequent hepatic AE (incidence rate of 21 per 1000 patients-years [CI 95% 18-23]), followed by NAFLD (8 cases per 1000 patients-years [95% CI 6-10]). Methotrexate (aIRR 3.06 [2.31-4.4]; p = 0.000) and cyclosporine (aIRR 2.37 [1.05-5.35]; p = .0378) were associated with an increased risk for hypertransaminasemia when compared to anti-TNF-α agents. No differences were observed between different groups of biologics. Conventional therapies were not associated with new incident NAFLD. CONCLUSIONS: Comparative information of the incidence of hepatic AEs could facilitate drug selection in moderate-to-severe psoriasis.

Histopathological findings in COVID-19-induced cutaneous lesions. Clinicopathological correlation of SARS-CoV-19 dermatologic patterns: review of the literature.

An increasing number of publications have brought attention to COVID-19-associated cutaneous lesions. Histopathological descriptions and clinical correlation of the histopathological findings of COVID-19 skin lesions are lacking. In this manuscript, we reviewed and described the histopathological characteristics of COVID-19 infection cutaneous patterns reported in the literature.

Effect of Sex in Systemic Psoriasis Therapy: Differences in Prescription, Effectiveness and Safety in the BIOBADADERM Prospective Cohort.

The effect of sex on systemic therapy for psoriasis has not been well studied. The aim of this study was to analyse a large multicentre Spanish cohort of 2,881 patients with psoriasis (58.3% males), followed from January 2008 to November 2018, to determine whether sex influences prescription, effectiveness of therapy, and the risk of adverse events. The results show that women are more likely than men to be prescribed biologics. There were no differences between men and women in effectiveness of therapy, measured in terms of drug survival. Women were more likely to develop adverse events, but the difference in risk was small and does not justify different management. Study limitations include residual confounding and the use of drug survival as a proxy for effectiveness.

Uso de metotrexato intralesional en el tratamiento de la enfermedad de Rosai-Dorfman / Intralesional methotrexate used in cutaneous Rosai-Dorfman disease

No disponible

Characterization of plant growth-promoting bacteria associated with avocado trees (Persea americana Miller) and their potential use in the biocontrol of Scirtothrips perseae (avocado thrips).

Plants interact with a great variety of microorganisms that inhabit the rhizosphere or the epiphytic and endophytic phyllosphere and that play critical roles in plant growth as well as the biocontrol of phytopathogens and insect pests. Avocado fruit damage caused by the thrips species Scirtothrips perseae leads to economic losses of 12-51% in many countries. In this study, a screening of bacteria associated with the rhizosphere or endophytic phyllosphere of avocado roots was performed to identify bacterial isolates with plant growth-promoting activity in vitro assays with Arabidopsis seedlings and to assess the biocontrol activity of the isolates against Scirtothrips perseae. The isolates with beneficial, pathogenic and/or neutral effects on Arabidopsis seedlings were identified. The plant growth-promoting bacteria were clustered in two different groups (G1 and G3B) based on their effects on root architecture and auxin responses, particularly bacteria of the Pseudomonas genus (MRf4-2, MRf4-4 and TRf2-7) and one Serratia sp. (TS3-6). Twenty strains were selected based on their plant growth promotion characteristics to evaluate their potential as thrips biocontrol agents. Analyzing the biocontrol activity of S. perseae, it was identified that Chryseobacterium sp. shows an entomopathogenic effect on avocado thrips survival. Through the metabolic profiling of compounds produced by bacteria with plant growth promotion activity, bioactive cyclodipeptides (CDPs) that could be responsible for the plant growth-promoting activity in Arabidopsis were identified in Pseudomonas, Serratia and Stenotrophomonas. This study unravels the diversity of bacteria from the avocado rhizosphere and highlights the potential of a unique isolate to achieve the biocontrol of S. perseae.

Long-term safety of nine systemic medications for psoriasis: A cohort study using the Spanish Registry of Adverse Events for Biological Therapy in Dermatological Diseases (BIOBADADERM) Registry.

BACKGROUND: Registry studies broadly describing the safety of systemic drugs in psoriasis are needed. OBJECTIVE: To describe the safety findings of the systemic drugs acitretin, adalimumab, apremilast, cyclosporine, etanercept, infliximab, methotrexate, secukinumab, and ustekinumab used for the treatment of moderate to severe psoriasis in patients included in the Spanish Registry of Adverse Events for Biological Therapy in Dermatological Diseases (BIOBADADERM) Registry. METHODS: The incidence rate ratio (IRR) and adjusted IRR (including propensity scores) of identified adverse events for each drug, using methotrexate as reference, were determined by means of a prospective cohort. RESULTS: Our study included 2845 patients (8954 treatment cycles; 9642 patient-years). Ustekinumab and secukinumab had the lowest rate of adverse events for several of the system organ classes, with a statistically significant decreased rate ratio (IRR of <1), whereas cyclosporine and infliximab had the highest, with an increased rate ratio (IRR of ≥5). LIMITATIONS: Observational study, drug allocation not randomized, depletion of susceptibles, and prescribed doses not registered. CONCLUSION: Our data provide comparative safety information in the real-life setting that could help clinicians selecting between available products.

Tuberculosis abdominal en niños de un hospital público de tercer nivel en México / Abdominal tuberculosis in children of a public tertiary hospital in Mexico

INTRODUCCIÓN. A nivel mundial la tuberculosis es una de las diez causas de muerte, con una incidencia de 7 920 pacientes entre 0 ­ 14 años en la región de América; siendo el abdomen el sitio extrapulmonar más común. OBJETIVOS. Describir las características etarias, clínicas, microbio-lógicas, complicaciones y comorbilidades asociadas en los pacientes pediátricos con tuberculosis abdominal. MATERIALES Y MÉTODOS. Estudio retrospectivo, base de datos de 23 pacientes y edades de 0 meses a 17 años 11 meses y 29 días de edad con evidencia confirmatoria de la presencia del microorganismo; de los servicios de Gastroenterología y Epidemiología en el Nuevo Hospital Civil de Guadalajara "Dr. Juan I. Menchaca ", período 2007 a 2018. RESULTADOS. Se informaron 47,8% (11; 23) de sexo masculino y 52,2% (12; 23) de sexo femenino; 26,1% (6; 23) con antecedente de ingesta de lácteos no pasteurizados. Los tres datos clínicos más frecuentes fueron dolor abdominal, fiebre y pérdida de peso. El 8,7% (2;23) tuvieron convivencia con personas con tuberculosis activa positivo; 30,4% (7; 23) registraron prueba cutánea de derivado proteico pu-rificado positiva; 30,4% (7; 23) identificación de bacterias ácido-alcohol resistentes positivo; 43,5% (10; 23) estudios de imagen compatibles; 8,7% (2; 23) proteína C reactiva de mucosa intestinal po-sitivo; 4,3% (1; 36) cultivo positivo y 8,7% (2; 23) pacientes con inmunodeficiencia. CONCLUSIÓN. La tuberculosis abdominal, se presentó en menores de edad con síntomas inespecíficos de dolor abdominal, fiebre y pérdida de peso, expuestos a ingesta de productos lácteos no pasteurizados, combe positivo e inmunodeficiencia.

INTRODUCTION. Worldwide, tuberculosis is one of the ten causes of death, with an incidence of 7 920 patients between 0 - 14 years in the Americas region; the abdomen being the most common extrapulmonary site. OBJECTIVES. Describe the age, clinical, microbiological, complications and associated comorbidities in pediatric patients with abdominal tuberculosis. MATERIALS AND ME-THODS. Retrospective study, database of 23 patients and ages from 0 months of age to 17 years 11 months and 29 days of age with confirmatory evidence of the presence of the microorganism; of the Gastroenterology and Epidemiology services at the New Civil Hospital of Guadalajara "Dr. Juan I. Menchaca ", period 2 007 to 2 018. RESULTS. 47,8% (11; 23) men and 52,2% (12; 23) women were reported; 26,1% (6; 23) with a history of unpasteurized dairy intake. The three most frequent clinical data were abdominal pain, fever and weight loss. 8,7% (2; 23) lived together with people with positive active tuberculosis; 30,4% (7; 23) recorded a positive purified protein derivative skin test; 30,4% (7; 23) positive acid-alcohol resistant bacteria identification; 43,5% (10; 23) compatible imaging studies; 8,7% (2; 23) positive intestinal mucosal C-reactive protein; 4,3% (1; 36) positive culture and 8,7% (2; 23) patients with immunodeficiency. CONCLUSION. Abdominal tuberculosis occurred in minors with nonspecific symptoms of abdominal pain, fever and weight loss, exposed to intake of unpasteurized dairy products, positive combe and immunodeficiency

Seedling Characteristics of Three Oily Species before and after Root Pruning and Transplant.

Moringa oleifera Lam. (Moringa), Jatropha curcas L. (Jatropha), and Ricinus communis L. (Ricinus) are oily species known by their capability to grow in tropical and subtropical lands. However, there are no studies comparing their growth and recovery capabilities after root pruning and transplant. The purpose of this research was to compare and analyze propagation, growth, and recovery performance of these species after root pruning and transplant. We sowed 100 seeds per species and monitored their survival and growth during a 63-day period; after this, we uprooted the plants and pruned their roots 4.0 cm from their base and transplanted them. We monitored their recovery over 83 days, and then uprooted plants and measured above- and belowground data, digitized their roots in three dimensions, and calculated biomass fractions. With this information, we established allometric equations to estimate biomass fractions and root distribution models. Results indicated that Ricinus had the highest propagation capabilities. Jatropha and Ricinus had similar recovery after root pruning and transplant. Moringa had the lowest propagation and recovery from transplant. Concerning belowground data, root pruning increased root density more than three times in Moringa, four times in Ricinus, and six times in Jatropha. Nevertheless, the three species maintained natural root trays. Ricinus had the longest and thinnest roots and the highest number of branches, followed by Jatropha, and finally Moringa, with the smallest quantity and the shortest and thickest roots. We concluded that the three species recovered well from root pruning and transplant, with improved root structure upon applying these practices.

IMPACT OF CRUDE OIL ON FUNCTIONAL GROUPS OF CULTURABLE BACTERIA AND COLONIZATION OF SYMBIOTIC MICROORGANISMS IN THE Clitoria-Brachiaria RHIZOSPHERE GROWN IN MESOCOSMS / Impacto del petróleo crudo sobre grupos funcionales de bacterias cultivables y colonización de microorganismos simbióticos en la rizosfera de Clitoria-Brachiaria crecidas en mesocosmos

ABSTRACT This research evaluated the changes on populations of culturable N-fixing free bacteria (NFFB) and P-solubilizing bacteria (PSB), as well as on the root nodulation by native rhizobia, the root colonization and spore number of arbuscular mycorrhizal fungi (AMF), in the rhizosphere of Clitoria ternatea and Brachiaria brizantha grown in mesocosms contaminated with crude oil (0, 3000, 6000, 9000, and 12000 mg kg-1), for 240 days. After 24 h of soil contamination, the highest populations of NFFB and PSB (5.5 and 4.9 LogUFC, respectively) were found in control, and the lowest populations were obtained at 12000 mg kg-1 (5.1 and 4.2 LogUFC, respectively). In contrast, at 60 and 240 days, the control showed lower populations of NFFB and PSB (5.4 and 4.8 LogUFC, respectively) than contaminated treatments. The highest number of root nodules in C. ternatea was quantified in control at 60 and 240 days (25 and 27 nodules, respectively) in comparison to those observed at the treatment with 12000 mg kg-1 (7 and 1 nodule, respectively). At 60 days, AMF colonization in both plant species, and the number of spores significantly decreased as the crude oil concentration increased; however, at 240 days, the highest number of AMF spores was recorded at treatments with 6000 and 12000 mg kg-1. The dry weight of both plant species significantly decreased as crude oil concentrations increased. Although C. ternatea was more susceptible to the toxic effects of crude oil, this plant species showed greater content of total chlorophyll than B. brizantha.

RESUMEN Esta investigación evaluó los cambios en la población cultivable de bacterias de vida libre fijadoras de nitrógeno (BVLFN) y de bacterias solubilizadoras de fósforo (BSP), así como en la nodulación de raíces por rizobios nativos, y en la colonización y número de esporas de hongos micorrízicos arbusculares (HMA) en la rizósfera de Clitoria ternatea y Brachiaria brizantha cultivadas en mesocosmos contaminados con petróleo crudo (0, 3000, 6000, 9000 y 12000 mg kg-1), durante 240 días. A las 24 h de la contaminación del suelo, las poblaciones más altas de BVLFN y BSP (5,5 y 4,9 LogUFC, respectivamente) se encontraron en el control, mientras que las poblaciones más bajas se obtuvieron a 12000 mg kg-1 (5,1 y 4,2 LogUFC, respectivamente). En contraste, a los 60 y 240 días, el control mostró bajas poblaciones de BVLFN y BSP (5,4 y 4,8 LogUFC, respectivamente) que los tratamientos contaminados. El mayor número de nódulos en raíz de C. ternatea se cuantificó en el control a los 60 y 240 días (25 y 27 nódulos, respectivamente) en comparación con el tratamiento con 12000 mg kg-1 (7 y 1 nódulos, respectivamente). A los 60 días, la colonización de HMA en ambas especies vegetales y el número de esporas disminuyeron significativamente al aumentar la concentración de petróleo crudo; sin embargo, a los 240 días, se registró el mayor número de esporas de HMA en los tratamientos con 6000 y 12000 mg kg-1. El peso seco vegetal disminuyó significativamente al aumentar las concentraciones de petróleo crudo. Clitoria ternatea fue más susceptible a la toxicidad del petróleo, aunque esta especie vegetal mostró mayor contenido de clorofila total que B. brizantha.