Microbial growth in biobeds for treatment of residual pesticide in banana plantations.

BACKGROUND: High doses of ethylenebisdithiocarbamate (EBDC) are used in banana production, and unused pesticide mixture (solution) is often disposed of improperly. This can result in soil and water contamination and present an undue risk to rural communities and the environment. An alternative to reduce the environmental impacts caused by pesticide residues is the biobeds treatment. It is necessary to establish if the composition of the proposed biomixtures supports microbial activity to degrade pesticides in biobeds. This research aimed to evaluate the EBDC effect on the distribution and abundance of microbial populations in polluted biomixtures . METHODS: For this purpose, a biomixture based on banana stem, mulch, and Fluvisol soil (50:25:25% v/v) was prepared and polluted with 1,000 mg L-1 EBDC. The response variables kinetics were determined every 14 days for three months, such as pH, organic matter, moisture, cation exchange capacity, microbial colonies, and cell counts at three depths within the experimental units. RESULTS: EBDC reduced the number of microbial colonies by 72%. Bacterial cells rapidly decreased by 69% and fungi 89% on the surface, while the decrease was gradual and steady at the middle and bottom of the biobed. The microbial populations stabilized at day 42, and the bacteria showed a total recovery on day 84, but the fungi slightly less. At the end of the experiment, the concentration of EBDC in the biomixture was 1.3-4.1 mg L-1. A correlation was found between fungal count (colonies and cells) with EBDC concentration. A replacement of the biomixture is suggested if the bacterial population becomes less than 40 × 106 CFU mL-1 and the fungal population less than 8 × 104 CFU mL-1 or if the direct cell count becomes lower than 50 × 104 cells mL-1 in bacteria and 8 × 102 cells mL-1 in fungi. CONCLUSION: The biomixture based on banana stem supports the microbial activity necessary for the degradation of the EBDC pesticide. It was found that fungi could be used as indicators of the pollutant degradation process in the biomixtures. Microbial counts were useful to establish the mobility and degradation time of the pesticide and the effectiveness of the biomixture. Based on the results, it is appropriate to include the quantification of microbial populations to assess the effectiveness of pesticide degradation and the maturity level of the biomixture.

Substrate evaluation for biobeds in the degradation of ethylene bis-dithiocarbamate in wastewater from pesticide application in banana.

The efficacy of biobeds was evaluated by testing three agricultural residues (sugarcane top, banana stem, and eucalyptus chip) as substrates for the degradation of ethylene bis-dithiocarbamate (EBDC) and ethylene thiourea (ETU) in wastewater from banana spraying. Acrylic columns with a capacity to treat 1 L/ea. of wastewater were used as experimental units. Each unit was filled with different proportions of the test substrate (30%, 50% and 70% v/v) and the difference in volume was made up of equal parts of sugar cane cachasse and Fluvisol soil. Subsequently, the units were contaminated with suspensions of 878 mgL-1 of EBDC, and the dose was repeated periodically. The ETU concentration and leachate toxicity were evaluated every month for six months. The mixtures with 30% sugarcane top and 50% eucalyptus chip gave the best results, with leachable ETU concentrations down to a level protective of the environment, and toxicity down to background levels or nearly so. This was only found in mixtures with a high C:N ratio (20-25), thus, the effectiveness of the biobeds appears to be related to high lignolytic activity. .

El proceso analítico jerárquico como metodología para seleccionar revistas científicas en el área biotecnológica

l objetivo de este trabajo es establecer una metodología apropiada para seleccionar una revista para publicar en el área biotecnológica, a través del proceso analítico jerárquico. La publicación de artículos en revistas indizadas es una de las metas fundamentales del trabajo de investigación científica. Por eso es importante seleccionar la revista que mejor proyecte la información del artículo entre la comunidad técnico-científica; sin embargo, depender de criterios subjetivos puede derivar en la pérdida de tiempo y energía, costos innecesarios y una baja difusión de la productividad científica del investigador. Para establecer la metodología se evaluaron 11 parámetros cualitativos y cuantitativos de 20 revistas científicas, validadas por un grupo de expertos en el área, luego se usó un proceso de análisis jerárquico con lo que se estableció el criterio de selección. Se encontró que los elementos clave para considerar la selección de una revista son el factor de impacto, el tiempo de aceptación, el tipo de indización y la cantidad de artículos publicados por la revista. De esta forma, con una metodología para escoger la revista idónea, se puede aumentar las posibilidades de publicar el artículo, disminuir el tiempo de espera, gastos de publicación y lograr tener un mayor número de citas una vez publicado, usando una diversidad de criterios y no únicamente criterios bibliométricos como el factor de impacto.

he aim of this study is to establish an applicable methodology for the selection of a journal when aspiring to publish a scientific work in the biotechnology field, using the hierarchical analytical process. The publication of papers in indexed journals is one of the main goals of scientific research work. That's why it is of great importance to select the journal that best disseminates the information of the paper among the technical-scientific community; however, having to rely on subjective criteria in the journal selection process can result in time and energy waste, unnecessary costs and a low dissemination of the researcher's scientific productivity. To establish the methodology, 11 qualitative and quantitative parameters of 20 scientific journals were evaluated, validated by a group of experts in the area, followed by a hierarchical analysis process, which established the selection criteria. It was found that the key elements to consider the journal selection are the impact factor, the acceptance time, the type of indexing and the number of articles published by the journal. Thus, with a methodology to choose the appropriate journal, it is possible to increase the possibilities of publishing the article, decrease the waiting time, publication costs and achieve a larger number of citations once published, using a variety of criteria and not just bibliometric criteria as the impact factor.

Inconsistencies and ambiguities in calculating enzyme activity: The case of laccase.

Laccase is a key enzyme in the degradation of lignin by fungi. Reports indicate that the activity of this enzyme ranges from 3.5 to 484,000 U L(-1). Our aim was to analyze how laccase activity is calculated in the literature, and to determine statistically whether variations in activity are due to biological properties or to inconsistencies in calculation. We found a general lack of consensus on the definition of enzyme activity, and enzymes are sometimes characterized in terms of reaction rate and specific activity. Moreover, enzyme activity is calculated using at least seven different equations. Therefore, it is critical to standardize the calculation of laccase activity in order to compare results directly.

Production of short-chain fatty acids from the biodegradation of wheat straw lignin by Aspergillus fumigatus.

The wheat straw lignin-rich fraction (WSLig-RF) can be used as a raw material for the production of metabolites for industrial use if ligninolytic mitosporic fungi are used for its biodegradation into aromatics and short-chain fatty acids (SCFAs, i.e., SCFA2-6). Although methods for the production of SCFA2-6 have been described previously, quantitative data of SCFA2-6 production have not been reported. The objectives of this study were to investigate the biodegradation of different concentrations of WSLig-RF by Aspergillus fumigatus and to identify whether SCFA2-6 production was dependent on the concentration of aromatics. A. fumigatus generated 2805mgL(-1) acetic acid when mixed with WSLig-RF at a concentration of 20gL(-1). Thus, aromatics are a substrate for the biosynthesis of SCFA2-6, and their production depends on the concentration of WSLig-RF aromatics.

Generación de monómeros aromáticos por Aspergillus y Penicillum spp a partir de lignina residual de paja de trigo / Aromatic monomers generation by Aspergillus and Penicillium spp from residual wheat straw lignin

Antecedentes: La paja de trigo es un residuo agrícola con un 17% de lignina, un polímero recalcitrante con potencial biotecnológico si se despolimeriza en aromáticos de interés para la industria; lo que es posible por métodos químicos, pero que son costosos y contaminantes. Una alternativa es su despolimerización biológica por hongos mitospóricos ligninolíticos como Aspergillus y Penicillium spp. Sin embargo existen pocos reportes del uso de hongos en la generación de aromáticos por despolimerización de la lignina de residuos agrícolas. Objetivo: Determinar la generación de aromáticos utilizando los hongos Aspergillus y Penicillium por despolimerización de la lignina residual de paja de trigo semipurificada. Métodos: Para ello los hongos se cultivaron en lignina residual de paja de trigo por 28 días, que por despolimerización generaron aromáticos que se identificaron en cromatografía de gases. Resultados: Los resultados mostraron que ambos hongos generan aromáticos como: guayacol 3,5, vainillina 3,3, ácidos hidroxibenzoico 3,2, vainillinico 3,3, siringico 10,1 y ferúlico 21,9 mg mL-1. Conclusiones: Aspergillus y Penicillium son una opción ecológica en el aprovechamiento de la lignina residual de paja de trigo semipurificada para la generación de aromáticos de interés industrial, en un tiempo relativamente corto a partir de un residuo abundante y barato.

Background: Wheat straw is an agricultural waste, which contains 17% of lignin, a recalcitrant polymer with biotechnological potential provided it is depolymerized. Lignin depolymerization has attracted interest because it yields aromatics of industrial interest; chemical and physical methods are available but entail economic and environmental constraints. An alternative is to exploit the ligninolytic capacity of mitosporic fungi, such as Aspergillus and Penicillium spp. There are few reports on the use of these funguses in the generation of aromatics by lignin depolymerization. Objetives: To use Aspergillus and Penicillium spp in the biological generation of aromatics from semipurified residual wheat straw lignin. Methods: Funguses were grown in semipurified residual wheat straw lignin for 28 days; produced aromatics were followed using gas chromatography. Results: Obtained results indicate a range of aromatics produced, i.e. 3,5 mg mL-1 guaiacol, 3,3 vanillin, 3,2 hydroxybenzoic acid, 3,3 vanillinic, 10,1 syringic and 21,9 ferulic. Conclusions: Aspergillus and Penicillium represent an ecological option in the exploit of semi-purified residual lignin from wheat straw to generate aromatics in a shorter period from an abundant and cheap residue.