Characterization and survival of broad-spectrum biocontrol agents against phytopathogenic fungi / Caracterización y supervivencia de agentes de control biológico de amplio espectro frente a hongos fitopatógenos

Resumen Este estudio tuvo como objetivo aislar, caracterizar e identificar bacterias de control biológico que poseen actividad antifúngica de amplio espectro de la filosfera de diferentes cultivos, incluidos el maíz, el trigo y la papa, así como evaluar su actividad en la promoción del crecimiento. En este estudio, 14/113 bacterias de control biológico mostraron actividad antifúngica. Los aislamientos bacterianos M11 y M33 (de maíz), del total de 113, fueron reseleccionados debido a su fuerte actividad antifúngica de amplio espectro (más del 50%) después de su evaluación contra cuatro hongos fitopatógenos que afectan cultivos de alta importancia económica, entre ellos, Alternaría alternata, Rhizoctonia solani, Fusarium oxysporum y Fusarium verticillioides. Los aislamientos se evaluaron, adicionalmente, para determinar los rasgos que promueven el crecimiento de las plantas, es decir, producción de ácido indolacético, solubilización de fosfato, producción de celulasa, compuestos orgánicos volátiles microbianos, cianuro de hidrógeno y sideróforos. Las 14 cepas aisladas mostraron resultados positivos para la producción de la hormona ácido indolacético y la enzima celulasa; 10 cepas fueron positivas para la producción de cianuro de hidrógeno. Además, se observó producción de sideróforos en el caso de 7 cepas, mientras que 5 pudieron solubilizar fosfato inorgánico. Los compuestos orgánicos volátiles microbianos solo fueron sintetizados por los aislamientos M11 y M33, que fueron identificados como Bacillus amyloliquefaciens y Bacillus subtilis, respectivamente, mediante secuenciación del gen ARNr 16S. El estudio de supervivencia mostró que las bacterias de control biológico, es decir, B. amyloliquefaciens y B. subtilis, tienen la capacidad de sobrevivir sobre un sustrato a base de melasa, por un período de tres meses.

Comparison of GeneXpert MTB/RIF assay and LED-FM microscopy for the diagnosis of extra pulmonary tuberculosis in Khyber Pakhtunkhwa, Pakistan

ABSTRACT GeneXpert is one of the recent technological instruments used to diagnose tuberculosis in a short span of time. In this study, the performance of GeneXpert MTB/RIF assay for the diagnosis of extrapulmonary tuberculosis (EPTB) was compared with light-emitting diode Fluorescent Microscopy (LED-FM) in Khyber Pakhtunkhwa, Pakistan. A total of 737 EPTB samples were collected from tuberculosis (TB) suspected patients. Out of these samples, male to female ratio was 53% (n = 390) to 47% (n = 347) respectively. The sensitivity and specificity was 73% and 100% for GeneXpert, while 40% and 100% for LED-FM microscopy. This shows that the sensitivity of GeneXpert is 40-50%, higher than LED-FM microscopy. GeneXpert also detected low number of bacilli as compared to LED-FM microscopy.

Improved antifungal activity of barley derived chitinase I gene that overexpress a 32 kDa recombinant chitinase in Escherichia coli host

Abstract Agricultural crops suffer many diseases, including fungal and bacterial infections, causing significant yield losses. The identification and characterisation of pathogenesis-related protein genes, such as chitinases, can lead to reduction in pathogen growth, thereby increasing tolerance against fungal pathogens. In the present study, the chitinase I gene was isolated from the genomic DNA of Barley (Hordeum vulgare L.) cultivar, Haider-93. The isolated DNA was used as template for the amplification of the ∼935 bp full-length chitinase I gene. Based on the sequence of the amplified gene fragment, class I barley chitinase shares 93% amino acid sequence homology with class II wheat chitinase. Interestingly, barley class I chitinase and class II chitinase do not share sequence homology. Furthermore, the amplified fragment was expressed in Escherichia coli Rosetta strain under the control of T7 promoter in pET 30a vector. Recombinant chitinase protein of 35 kDa exhibited highest expression at 0.5 mM concentration of IPTG. Expressed recombinant protein of 35 kDa was purified to homogeneity with affinity chromatography. Following purification, a Western blot assay for recombinant chitinase protein measuring 35 kDa was developed with His-tag specific antibodies. The purified recombinant chitinase protein was demonstrated to inhibit significantly the important phytopathogenic fungi Alternaria solani, Fusarium spp, Rhizoctonia solani and Verticillium dahliae compared to the control at concentrations of 80 µg and 200 µg.

Enhancing Bio-Available Phosphorous in Soil Through Sulfur Oxidation by Thiobacilli.

Aims: The objectives were to evaluate the phosphate solubilization efficiency of different Thiobacilli strains and to find out the best combination of sulfur and Thiobacilli for enhancing bio-available P in soil. Study Design: An experimental study. Place and Duration of Study: Microbiology and Soil Fertility Labs, Department of Soil Science and Soil and Water Conservation, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan and Microbiology and Soil Chemistry Labs, Auriga Research Center, Lahore, Pakistan, between May 2011 and November 2012. Methodology: Fifty Thiobacilli strains were isolated from ten different ecologies. Then an incubation study of soil was performed wherein the most efficient four Thiobacilli strains were inoculated in combination with three different levels of elemental sulfur to determine pH, water soluble sulfur, sequential P fractions and bio-available phosphorous contents in the incubated soil. Results: All the four Thiobacillus strains (IW16, SW2, IW1 and IW14) dropped pH of the incubated soil along with three doses of S° (50, 75 and 100 kg ha-1). However, Thiobacillus strains IW16 and SW2 reduced soil pH quite sharply from 7.90 to 7.12 (net reduction of 0.78 points) and 7.28 (net reduction of 0.62 points) respectively where inoculated with S° @ 100 kg ha-1. The best P solubilizer was Thiobacillus strain IW16 and the best dose of S° was @ 100 kg ha-1 and their combination enhanced maximum quantity of P (22.26 mg kg-1) in the soil by solubilizing already present insoluble calcium bounded P fractions like octacalcium phosphate (Ca8-P) and apatite (Ca10-P). Conclusion: The present study suggests the use of Thiobacilli along with elemental sulfur for the dissolution and enhancement of bio-available P in alkaline and calcareous soils.

Transvenous Permanent Pacemaker Implantation in 14 Month Old baby with Congenital Complete Heart Block.

Congenital Complete Heart Block in utero has been diagnosed more frequently with the clinical use of fetal echocardiography. The fetus with complete heart block may remain asymptomatic or develop congestive heart failure. Pacemaker therapy in children involves unique issues regarding patient size, growth, development and possible presence of congenital heart disease. Historically, epicardial pacing was more common in children. As technology has improved, generators and leads have become smaller and more advanced, allowing transvenous pacing system in children. Pacemaker therapy is even technically feasible in infants and neonates. We present a 14mth old baby of just 7.5kg who presented to us with Adams Stokes and subtle signs of congestive heart failure that after stabilization was implanted a transvenous MRI compatible permanent pacemaker (VVIR).