Jorge Machuca (Perú) - Autor; Rolando Castellares (Perú) - Comentarista; Fernando Merino (Perú) - Autor

Since the industrial revolution, the science and technology advances have increased the human ability to exploit natural resources causing pollution in ecosystems. In this context, the use of biosurfactants represents a promising alternative application for any technological process of remediation of natural environments. The objective of this work was the evaluation of the emulsifying activity and the ability to remove heavy metals with a rhamnolipidic biosurfactant produced by Pseudomonas aeruginosa PB25. This strain had a specific growth rate (μ) of 0.0285 h-1 and a generational time (td) of 24.321 h. It produced 2.47 g/L rhamnolipid, with yields (Y) of 0.13 g/g and productivity of 0.082 g/L-h. The rhamnolipid had 5.257 emulsifying activity units/mL and E24 emulsification index of 53, 64, 62 and 84% for crude oil, diesel oil 2, gasoline and kerosene, respectively. It got to remove 98...

In this paper, we describe the isolation and biodegradation activity of microorganisms on low density polyethylene. The microorganisms were collected from plastic materials with evidence of deterioration from a landfill. The samples were filtered and selected in a mineral salts medium at pH 5.5 and 7 for bacteria and fungi respectively. Six strains were isolated, identified as Pseudomonas sp. Hyalodendron sp., Penicillium sp. and Rhodotorula sp. Microbial activity was evidenced by changes in the infrared spectrum of polyethylene with respect to the polymer without treatment. Reduction of carbonyl index (83.89% at pH 7 and 4.08% at pH 5.5) and double bonds index (19.77% at pH 7 and 6.47% at pH 5.5) were observed. Finally we determined the percentage of weight lost by the polyethylene subjected to activity of the strains, with a decrease of 5.4% at pH 7 and 4.8% at pH5, 5.

The specificity between bacteriophages and bacteria is a feature that has been successfully used for the detection of several microbial species. For this reason the detection of vibriophages is a valuable research tool, and it might be a fast and convenient method to Vibrio cholerae diagnostics. The goal of this study was to detect vibriophages in shallow seawater samples and to determine the morphological characteristics of these vibriophages. It was determined the growth kinetics of a strain of Vibrio cholerae serotype Inaba. Seawater samples taken from five shallow points from an adjacent sector to La Chira beach, and Rímac and Chillón river mouths were analyzed qualitatively and quantitatively using different inoculum volumes and several incubation periods. The bacteriophages were concentrated and stained for the morphological study by transmission electron microscopy. The results ...

In this paper, we describe the isolation and biodegradation activity of microorganisms on low density polyethylene. The microorganisms were collected from plastic materials with evidence of deterioration from a landfill. The samples were filtered and selected in a mineral salts medium at pH 5.5 and 7 for bacteria and fungi respectively. Six strains were isolated, identified as Pseudomonas sp. Hyalodendron sp., Penicillium sp. and Rhodotorula sp. Microbial activity was evidenced by changes in the infrared spectrum of polyethylene with respect to the polymer without treatment. Reduction of carbonyl index (83.89% at pH 7 and 4.08% at pH 5.5) and double bonds index (19.77% at pH 7 and 6.47% at pH 5.5) were observed. Finally we determined the percentage of weight lost by the polyethylene subjected to activity of the strains, with a decrease of 5.4% at pH 7 and 4.8% at pH5, 5.

The specificity between bacteriophages and bacteria is a feature that has been successfully used for the detection of several microbial species. For this reason the detection of vibriophages is a valuable research tool, and it might be a fast and convenient method to Vibrio cholerae diagnostics. The goal of this study was to detect vibriophages in shallow seawater samples and to determine the morphological characteristics of these vibriophages. It was determined the growth kinetics of a strain of Vibrio cholerae serotype Inaba. Seawater samples taken from five shallow points from an adjacent sector to La Chira beach, and Rímac and Chillón river mouths were analyzed qualitatively and quantitatively using different inoculum volumes and several incubation periods. The bacteriophages were concentrated and stained for the morphological study by transmission electron microscopy. The results ...

Esta investigación tuvo como objetivos determinar el crecimiento de la concha de abanico, Argopecten purpuratus sometida a experimentación; determinar la diversidad de los epibiontes de la especie; determinar la mortalidad de la concha de abanico experimental; identificar la concentración de salinidad y tiempo de tratamiento adecuados para reducir los epibiontes con la menor mortalidad de los organismos cultivados. Se realizó un experimento factorial con tres concentraciones de salinidad aplicadas como baños por 5, 10 y 15 minutos para controlar los epibiontes. El crecimiento en peso de A. purpuratus varió entre 11,19 g, como mínimo y 20,55 g como máximo. El crecimiento en altura valvar fluctuó entre 8.15 mm como mínimo y 11,9 mm como máximo. La composición de epibiontes de la concha de abanico estuvo dada por un reducido número de especies: Hydroides sp, Balanus, Semimitylu...

Use of biosurfactants in bioremediation, facilitates and accelerates microbial degradation of hydrocarbons. CTAB/MB agar method created by Siegmund & Wagner for screening of rhamnolipids (RL) producing strains, has been widely used but has not improved significantly for more than 20 years. To optimize the technique as a quantitative method, CTAB/MB agar plates were made and different variables were tested, like incubation time, cooling, CTAB concentration, methylene blue presence, wells diameter and inocula volume. Furthermore, a new method for RL detection within halos was developed: precipitation of RL with HCl, allows the formation a new halos pattern, easier to observe and to measure. This research reaffirm that this method is not totally suitable for a fine quantitative analysis, because of the difficulty to accurately correlate RL concentration and the area of the halos. RL dif...

Use of biosurfactants in bioremediation, facilitates and accelerates microbial degradation of hydrocarbons. CTAB/MB agar method created by Siegmund & Wagner for screening of rhamnolipids (RL) producing strains, has been widely used but has not improved significantly for more than 20 years. To optimize the technique as a quantitative method, CTAB/MB agar plates were made and different variables were tested, like incubation time, cooling, CTAB concentration, methylene blue presence, wells diameter and inocula volume. Furthermore, a new method for RL detection within halos was developed: precipitation of RL with HCl, allows the formation a new halos pattern, easier to observe and to measure. This research reaffirm that this method is not totally suitable for a fine quantitative analysis, because of the difficulty to accurately correlate RL concentration and the area of the halos. RL dif...

Genes associated to rhamnolipids production were molecularly characterized in 61 bacterial strains from LAMYBIM bacterial collection (Laboratorio de Microbiología y Biotecnología Microbiana, Universidad Nacional Mayor de San Marcos, Perú). Strains were isolated from peruvian environments hydrocarbons polluted and were classified as RL overproducers (n= 21), RL producers (n = 20) and non-producers (n = 20) producers. Molecular identification using the 16S rRNA gene was preceded by the biochemical identification of 61 strains selected with the API 20 NE system. Pseudomonas aeruginosa was the most prevalent strain of the RL overproducers and RL producers. Species such as Burkholderia cepacea, Pseudomonas fluorescens, Aeromonas hydrophila and Chryseobacterium indologenes, were found too. In the same way, non-producers microorganisms were also characterized. The PCR amplification and agaro...

Se realizó la caracterización molecular de los genes asociados a la producción de ramnolípidos (RL), en 61 cepas bacterianas de la colección del Laboratorio de Microbiología y Biotecnología Microbiana (LAMYBIM) de la Universidad Nacional Mayor de San Marcos, Perú. Las cepas provenian de entornos peruanos contami-nados con hidrocarburos y fueron catalogadas como sobreproductoras de RL(n= 21), productoras de RL (n= 20) y no productoras de RL (n= 20). Las 61 cepas fueron identificadas bioquímicamente con el sistema API 20 NE. La identificación molecular se realizó empleando el gen del RNAr 16S. Se encontró que Pseudomonas aeruginosa fue el microorganismo de mayor prevalencia en los estratos sobreproductores y productores de ramnolípidos. Además, se encontraron: Burkholderia cepacea, Pseudomonas fluorescens, Aeromonas hydrophila y Chryseobacterium indologenes. Los microorganism...