Process Improvement of Coir Pith Degradation Involving White Rot Fungi By Substitution of Urea With Nitrogen Fixing Bacteria and Application of Biodegraded Coir Pith as Plant Growth Medium

In this study, a novel improved technology could be developed to convert the recalcitrant coir pith into environmental friendly organic manure. The standard method of composting involves the substitution of urea with nitrogen fixing bacteria viz. Azotobacter vinelandii and Azospirillum brasilense leading to the development of an improved method of coir pith. The combined action of the microorganisms could enhance the biodegradation of coir pith. In the present study, Pleurotus sajor caju, an edible mushroom which has the ability to degrade coir pith, and the addition of nitrogen fixing bacteria like Azotobacter vinelandii and Azospirillum brasilense could accelerate the action of the fungi on coir pith. The use of these microorganisms brings about definite changes in the NPK, Ammonia, Organic Carbon and Lignin contents in coir pith. This study will encourage the use of biodegraded coir pith as organic manure for agri/horti purpose to get better yields and can serve as a better technology to solve the problem of accumulated coir pith in coir based industries

The role of fungi and bacteria on the organic matter decomposition process in streams: interaction and relevance in biofilms

L'objectiu d'aquest estudi és el d'investigar sobre l'ús de matèria orgànica per part dels fongs i bacteris que colonitzen diferents substrats bentònics en rius Mediterranis i analitzar l'efecte dels factors ambientals i antròpics sobre l'estabilitat estructural i funcional de les comunitats del biofilm. La metodologia emprada en aquest estudi consisteix en: i) anàlisi de la biomassa bacteriana i fúngica, ii) anàlisi de la composició de les comunitats bentòniques (identificació d'hifomicets aquàtics i anàlisi del 16S rDNA bacterià), i iii) anàlisi de l'activitat enzimàtica extracel·lular relacionada amb el reciclatge de matèria orgànica en rius.

Pathogenicity and other genomic islands in plant pathogenic bacteria

Pathogenicity islands (PAIs) were first described in uropathogenic E. coli. They are now defined as regions of DNA that contain virulence genes and are present in the genome of pathogenic strains, but absent from or only rarely present in non-pathogenic variants of the same or related strains. Other features include a variable G+C content, distinct boundaries from the rest of the genome and the presence of genes related to mobile elements such as insertion sequences, integrases and transposases. Although PAIs have now been described in a wide range of both plant and animal pathogens it has become evident that the general features of PAIs are displayed by a number of regions of DNA with functions other than pathogenicity, such as symbiosis and antibiotic resistance, and the general term genomic islands has been adopted. This review will describe a range of genomic islands in plant pathogenic bacteria including those that carry effector genes, phytotoxins and the type III protein secretion cluster. The review will also consider some medically important bacteria in order to discuss the range, acquisition and stabilization of genomic islands.

Interaction of plant growth regulators and reactive oxygen species to regulate petal senescence in wallflowers (Erysimum linifolium)

Background In many species floral senescence is coordinated by ethylene. Endogenous levels rise, and exogenous application accelerates senescence. Furthermore, floral senescence is often associated with increased reactive oxygen species, and is delayed by exogenously applied cytokinin. However, how these processes are linked remains largely unresolved. Erysimum linifolium (wallflower) provides an excellent model for understanding these interactions due to its easily staged flowers and close taxonomic relationship to Arabidopsis. This has facilitated microarray analysis of gene expression during petal senescence and provided gene markers for following the effects of treatments on different regulatory pathways. Results In detached Erysimum linifolium (wallflower) flowers ethylene production peaks in open flowers. Furthermore senescence is delayed by treatments with the ethylene signalling inhibitor silver thiosulphate, and accelerated with ethylene released by 2-chloroethylphosphonic acid. Both treatments with exogenous cytokinin, or 6-methyl purine (which is an inhibitor of cytokinin oxidase), delay petal senescence. However, treatment with cytokinin also increases ethylene biosynthesis. Despite the similar effects on senescence, transcript abundance of gene markers is affected differentially by the treatments. A significant rise in transcript abundance of WLS73 (a putative aminocyclopropanecarboxylate oxidase) was abolished by cytokinin or 6-methyl purine treatments. In contrast, WFSAG12 transcript (a senescence marker) continued to accumulate significantly, albeit at a reduced rate. Silver thiosulphate suppressed the increase in transcript abundance both of WFSAG12 and WLS73. Activity of reactive oxygen species scavenging enzymes changed during senescence. Treatments that increased cytokinin levels, or inhibited ethylene action, reduced accumulation of hydrogen peroxide. Furthermore, although auxin levels rose with senescence, treatments that delayed early senescence did not affect transcript abundance of WPS46, an auxin-induced gene. Conclusions A model for the interaction between cytokinins, ethylene, reactive oxygen species and auxin in the regulation of floral senescence in wallflowers is proposed. The combined increase in ethylene and reduction in cytokinin triggers the initiation of senescence and these two plant growth regulators directly or indirectly result in increased reactive oxygen species levels. A fall in conjugated auxin and/or the total auxin pool eventually triggers abscission.

Effects of plant density and proportion on the interaction between wheat with alexandergrass plants

A determinação das relações competitivas entre espécies de plantas requer delineamentos experimentais e métodos de análise apropriados. A hipótese da pesquisa foi que duas espécies crescendo em convivência têm comportamento de crescimento e desenvolvimento distintos em função da sua competitividade relativa. O objetivo desta pesquisa foi quantificar a competitividade relativa da cultura do trigo com o capim-marmelada através da medida dos efeitos da densidade e da proporção de plantas, usando experimentos em série substitutiva. Monoculturas foram cultivadas em densidades de 1, 3, 5, 10 e 15 plantas por caixa e analisadas por regressão dos dados de massa seca, em 2006. Experimento em mistura foi cultivado nas proporções trigo:capim-marmelada de 0:6, 1:5, 2:4, 3:3, 4:2, 5:1 e 6:0 plantas por caixa e analisado através de interpretação gráfica de características de crescimento e produção, em 2007. Ambos os experimentos foram realizados em delineamento completamente casualizado com quatro repetições. Capim-marmelada foi mais sensível que trigo à competição intraespecífica. Capim-marmelada foi levemente mais competitivo que trigo. Número e massa de espigas e número de afilhos foram as características do trigo mais afetadas pela interferência do capim-marmelada.

Interaction between resistant tomato genotypes and plant extracts on Bemisia tabaci (Genn.) biotype B

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative genomic analysis of plant-associated bacteria

This review deals with a comparative analysis of seven genome sequences from plant-associated bacteria. These are the genomes of Agrobacterium tumefaciens, Mesorhizobium loti, Sinorhizobium meliloti, Xanthomonas campestris pv campestris, Xanthomonas axonopodis pv citri, Xylella fastidiosa, and Ralstonia solanacearum. Genome structure and the metabolism pathways available highlight the compromise between the genome size and lifestyle. Despite the recognized importance of the type III secretion system in controlling host compatibility, its presence is not universal in all necrogenic pathogens. Hemolysins, hemagglutinins, and some adhesins, previously reported only for mammalian pathogens, are present in most organisms discussed. Different numbers and combinations of cell wall degrading enzymes and genes to overcome the oxidative burst generally induced by the plant host are characterized in these genomes. A total of 19 genes not involved in housekeeping functions were found common to all these bacteria.

Interaction Between the Predator Podisus nigrispinus (Hemiptera: Pentatomidae) and the Entomopathogenic Bacteria Bacillus thuringiensis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Plant growth promoting bacteria in Brachiaria brizantha

Brachiaria brizantha is considered one of the preferred fodders among farmers for having high forage yield and large production of root mass. The association of beneficial bacteria with these grasses can be very valuable in the recovery of the pasture areas with nutritional deficiency. With the aim of studying this possibility, we carried out the sampling of soil and roots of B. brizantha in three areas (Nova Odessa-SP, So Carlos-SP and Campo Verde-MT, Brazil). Seventy-two bacterial strains were isolated and used in tests to evaluate their biotechnological potential. Almost all isolates presented at least one positive feature. Sixty-eight isolates produced analogues of indole-3-acetic acid, ten showed nitrogenase activity when subjected to the method of increasing the concentration of total nitrogen (total N) in the culture medium and sixty-five isolates showed nitrogenase activity when subjected to acetylene reduction technique. The partial sequencing of 16S rRNA of these isolates allowed the identification of seven main groups, with the prevalence of those affiliated to the genus Stenotrophomonas (69 %). At the end, this work elected the strains C4 (Pseudomonadaceae) and C7 (Rhodospirillaceae) as promising organisms for the development of inoculants due to their higher nitrogenase activity.

Phyllosphere Bacteria Improve Animal Contribution to Plant Nutrition

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Systematic Screening of Plant Extracts from the Brazilian Pantanal with Antimicrobial Activity against Bacteria with Cariogenic Relevance

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Diversity of propanil-degrading bacteria isolated from rice rhizosphere and their potential for plant growth promotion

The herbicide propanil has long been used in rice production in southern Brazil. Bacteria isolated from contaminated soils in Massaranduba, Santa Catarina, Brazil, were found to be able to grow in the presence of propanil, using this compound as a carbon source. Thirty strains were identified as Pseudomonas (86.7%), Serratia (10.0%), and Acinetobacter (3.3%), based on phylogenetic analysis of 16S rDNA. Little genetic diversity was found within species, more than 95% homology, suggesting that there is selective pressure to metabolize propanil in the microbial community. Two strains of Pseudomonas (AF7 and AF1) were selected in bioreactor containing chemotactic growth medium, with the highest degradation activity of propanil exhibited by strain AF7, followed by AF1 (60 and 40%, respectively). These strains when encapsulated in alginate exhibited a high survival rate and were able to colonize the rice root surfaces. Inoculation with Pseudomonas strains AF7 and AF1 significantly improved the plant height of rice. Most of the Pseudomonas strains produced indoleacetic acid, soluble mineral phosphate, and fixed nitrogen. These bacterial strains could potentially be used for the bioremediation of propanil-contaminated soils and the promotion of plant growth.