Chlorine dioxide against bacteria and yeasts from the alcoholic fermentation

The ethanol production in Brazil is carried out by fed-batch or continuous process with cell recycle, in such way that bacterial contaminants are also recycled and may be troublesome due to the substrate competition. Addition of sulphuric acid when inoculum cells are washed can control the bacterial growth or alternatively biocides are used. This work aimed to verify the effect of chlorine dioxide, a well-known biocide for bacterial decontamination of water and equipments, against contaminant bacteria ( Bacillus subtilis, Lactobacillus plantarum, Lactobacillus fermentum and Leuconostoc mesenteroides) from alcoholic fermentation, through the method of minimum inhibitory concentration ( MIC), as well as its effect on the industrial yeast inoculum. Lower MIC was found for B. subtilis ( 10 ppm) and Leuconostoc mesenteroides ( 50 ppm) than for Lactobacillus fermentum ( 75 ppm) and Lactobacillus plantarum ( 125 ppm). Additionally, these concentrations of chlorine dioxide had similar effects on bacteria as 3 ppm of Kamoran (R) ( recommended dosage for fermentation tanks), exception for B. subtilis, which could not be controlled at this Kamoran (R) dosage. The growth of industrial yeasts was affected when the concentration of chlorine dioxide was higher than 50 ppm, but the effect was slightly dependent on the type of yeast strain. Smooth yeast colonies ( dispersed cells) seemed to be more sensitive than wrinkled yeast colonies ( clustered cells/pseudohyphal growth), both isolated from an alcohol-producing unit during the 2006/2007 sugar cane harvest. The main advantage in the usage of chlorine dioxide that it can replace antibiotics, avoiding the selection of resistant populations of microorganisms.

Diversity of cry genes and genetic characterization of Bacillus thuringiensis isolated from Brazil

Two hundred and eighteen Bacillus thuringiensis isolates from Brazil were characterized by the presence of crystal protein genes by PCR with primers specific to different cry and cyt genes. Among these isolates, 95 were selected according to their geographic origin for genetic characterization with the 16S rRNA gene, RAPD, and plasmid profile. Isolates containing cryl genes were the most abundant (48%) followed by the cry11 and cyt (7%) and cry8 genes (2%). Finally, 40.3% of the isolates did not produce any PCR product. The plasmid profile and RAPD analysis showed a remarkable diversity among the isolates of B. thuringiensis not observed in the 16S rRNA gene. These results suggest that the genetic diversity of B. thuringiensis species results from the influence of different ecological factors and spatial separation between strains generated by the conquest of different habitats.

First isolation of microorganisms from the gut diverticulum of Aedes aegypti (Diptera: Culicidae): New perspectives for an insect-bacteria association

We show for the first time that the ventral diverticulum of the mosquito gut (impermeable sugar storage organ) harbors microorganisms. The gut diverticulum from newly emerged and non-fed Aedes aegypti was dissected under aseptic conditions, homogenized and plated on BHI medium. Microbial isolates were identified by sequencing of 16S rDNA for bacteria and 28S rDNA for yeast. A direct DNA extraction from Ae. aegypti gut diverticulum was also performed. The bacterial isolates were: Bacillus sp., Bacillus subtilis and Serratia sp. The latter was the predominant bacteria found in our isolations. The yeast species identified was Pichia caribbica.

Bacillus Thuringiensis mutant increase activity against Apodoptera Frugiperda larvae

Bacillus thuringiensis is a Gram-positive bacterium which main characteristic is the production of Cry proteins, that is toxic to some insects. These proteins, when ingested by susceptible insects, become active causing their death. In nature, it is possible to found B. thuringiensis strains which produce these proteins, but they differ in productivity (some of these isolates are more productive then others), and as to the toxicity levels of the produced proteins. Two B. thuringiensis strains that were highly effective against Spodoptera frugiperda larvae were chosen to verifying genetic mutation implication on Cry proteins productivity. One strain with a prolific spores production, while the other one only produced small amounts of spores. A genomic mutant library of these two isolates was, separately, constructed by genome Tn-5 transposon random insertion. Data analysis showed that mutation had a direct effect on the spores production, inducing an increase as well as a decrease in the production, according to the different strain observed. These results indicate, for the first time, that it is possible to use the described technique with B. thuringiensis, as well as the possibility to genetically breeding this bacteria. Another possibility introduced here is the possibility to do functional genetic studies mediated by mutagenesis in this bacterium.

Keratinase production by new strain of Bacillus Amyloliquefaciens: Application of statistical experimental design for optimization of keratinase production

Feathers are rich in amino acids and can be employed as a dietary protein supplement for animal feed. Microbial degradation is an alternative technology for improving the nutritional value of feathers. Other potential applications of keratinase include use in the leather industry, detergents and medicine as well as the pharmaceutical for the treatment of acne, psoriasis and calluses. A new keratinolytic enzyme production bacterium was isolated from a poultry processing plant. To improve keratinase yield, statistically based experimental designs were applied to optimize three significant variables: temperature, substrate concentration (feathers) and agitation speed. Response surface methodology demonstrated an increase in keratinolytic activity at temperature, agitation speed and substrate concentration of 26.6°C, 150 rpm and 2%, respectively. Liquid chromatography revealed the release of amino acids in the Bacillus amyloliquefaciens culture broth, thereby demonstrating the potential of feather meal in the animal feed industry. © Global Science Publications.

Gas phase photocatalytic bacteria inactivation using metal modified TiO2 catalysts

The present study describes the efficiency of heterogeneous photocatalytic reactor for the inactivation of three air born bacteria, Escherichia coli, Bacillus subtilis and Staphylococcus aureus using metal modified TiO2 photocatalysts and blacklight irradiation. The catalysts were prepared by photodeposition of silver, palladium or iron on commercial TiO2, immobilized on glass plates. X-ray photoelectron spectroscopy analysis was applied to determine the atomic percentage and species of each metal on the TiO2 surface, showing that 85% of silver, 73% of palladium and 45% of iron were present in metallic form on TiO2 surface. The plates were positioned on the inner lateral walls of a chamber through which the contaminated air flow passed for disinfection. Irradiation of bare TiO 2 resulted in 50% inactivation of E. coli while 41% and 35% inactivation of B. subtilis and S. aureus were obtained, respectively. When metal modified TiO2 was applied, the inactivation of B. subtilis was improved to 91% using Pd-TiO2 while of S. aureus was improved to 94% with Fe-TiO2, showing in this case no significant difference when compared to Ag-TiO2 and Pd-TiO2. In contrast, inactivation of E. coli was not significantly increased when metal modified TiO2 was used, ranging from 47% to 57%. © 2012 Elsevier B.V.

Avaliação de dois diferentes meios de cultura para o desenvolvimento de biopesticidas à base de Bacillus thuringiensis e sua aplicação em larvas de Aedes aegypti

The bacteria Bacillus thuringiensis var. israelensis (Bti) generates certain toxins with pesticide action, which can be used on the control of transmissible diseases by culicides, specially Aedes aegypti, the dengue vector. This biopesticide has been produced by submerged fermentation and, in Brazil, this production has been made by very little research centers and, more recently, by a unique small enterprise. For the implementation of a viable vectors control program through biopesticides, some studies about culture media are essential in order to join efficiency and low costs. In this way, agroindustrial wastes or by-products have been used as a nutrient source for the culture media production. In this study, corn steep liquor, a corn industrial processing by-product and tryptose, both with/without sugar addition, were compared as culture media. Cellular growth was evaluated by optical density at 620 nm, spore production by total viable cell count and LC50 by bioassays against 4th instar larvae. Among the four examined substrates, the medium composed by glucose plus corn steep liquor presented the best spore production and bioassay results.

Bacillus cereus e Bacillus subtilis na suplementação dietária de juvenis de Tilápias-do-Nilo (Oreochromis niloticus) e seu efeito probiótico

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Produção de levana por Bacillus subtilis e Zymomonas mobilis utilizando três meios de cultura sintéticos e um alternativo (caldo de cana-de-açucar)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Mecanismos de ação de Bacillus spp. envolvidos no biocontrole de Phyllosticta citricarpa

Pós-graduação em Microbiologia Agropecuária - FCAV

Caracterização de isolados de Bacillus thuringiensis patogênicos à Spodoptera frugiperda (Lepidoptera: Noctuidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Seleção e caracterização de novos genes vip3A: genes inseticidas de segunda geração de Bacillus thuringiensis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ação de Bacillus thuringiensis Berliner nas características biológicas de outrs inimigos naturais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Identificação e caracterização de um gene cry recombinante de Bacillus thuringiensis var. londrina

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Identificação, caracterização e teste de toxicidade contra nematóides de novos genes cry de Bacillus thuringiensis

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