Producción de plásticos biodegradables a partir de bacterias de hábitats salinos aisladas de la Laguna de Ayarza / Production of biodegradable plastics from saline habitats bacteria isolated from Laguna de Ayarza

La contaminación por plásticos petroquímicos es una grave amenaza para el medio ambiente que requiere im-plementar alternativas como los bioplásticos para lograr un desarrollo sostenible. Los polihidroxialcanoatos (PHA) son polímeros utilizados para la producción de plásticos biodegradables y que han llamado la atención como sustitutos de los plásticos de base fósil. Sin embargo, el costo de producción de los PHA constituye una barrera para su producción industrial a gran escala. Las de bacterias de hábitats salinos son microorganismos prometedores para la síntesis de PHA debido a sus características tales como altos requisitos de salinidad que previenen la contaminación microbiana, la alta presión osmótica intracelular que permite una fácil lisis celular para purificar los PHA y la capacidad para usar un amplio espectro de sustratos. La presente investigación planteó determinar las cepas nativas de bacterias halófilas y halotolerantes de la Laguna de Ayarza capaces de producir PHA, establecer la capacidad que tienen de utilizar residuos agrícolas para la producción de PHA y determinar su eficiencia. Esto se logró a través de la inoculación de las cepas productoras de PHA en medios de fermentación con pulpa de café, cáscaras de plátanos y salvado de trigo lo que permitió determinar las cepas más eficientes. Se encontró que las bacterias productoras de PHA pertenecen a las especies: Alcaligenes faecalis, Bacillus idriensis, Bacillus megaterium, Exiguobacterium acetylicum, E. aurantiacum, Pseudomonas cuatrocienegasensis y Sta-phylococcus capitis y que las cepas AP21-14, AP21-10 y AP21-03 mostraron los mejores resultados que podrían ser prometedores para la producción a nivel industrial.

Pollution by petrochemical plastics is a serious threat to the environment that requires the implementation of al-ternatives such as bioplastics to achieve sustainable development. Polyhydroxyalkanoates (PHAs) are polymers used for the production of biodegradable plastics and have drawn attention as substitutes for fossil-based plastics. However, the cost of producing PHAs constitutes a barrier to their large-scale industrial production. Bacteria from saline environments bacteria are promising microorganisms for PHA synthesis due to their characteristics such as high salinity requirements that prevent microbial contamination, high intracellular osmotic pressure that allows easy cell lysis to purify PHAs, and the ability to use a broad spectrum of substrates. This research project aimed to determine the native strains of halophilic and halotolerant bacteria from Laguna de Ayarza capable of producing PHA, establish their ability to use agricultural residues for the production of PHA, and determine their efficiency. This was achieved through the inoculation of the PHA-producing strains in fermentation media with coffee pulp, banana peels and wheat bran, which allowed determining the most efficient strains. It was found that the PHA-producing bacteria belong to the species: Alcaligenes faecalis, Bacillus idriensis, Bacillus mega-terium, Exiguobacterium acetylicum, E. aurantiacum, Pseudomonas cuatrocienegasensis and Staphylococcus capitis and that the strains AP21-14, AP21-10 and AP21-03 showed the best results that could be promising for production at an industrial level.

Antiproliferative activity of biomass extract from Pseudomonas cedrina

Background: The study of plant-associated microorganisms is very important in the discovery and development of bioactive compounds. Pseudomonas is a diverse genus of Gammaproteobacteria comprising more than 60 species capable of establishing themselves in many habitats, which include leaves and stems of many plants. There are reports of metabolites with diverse biological activity obtained from bacteria of this genus, and some of the metabolites have shown cytotoxic activity against cancer cell lines. Because of the high incidence of cancer, research in recent years has focused on obtaining new sources of active compounds that exhibit interesting pharmacodynamic and pharmacokinetic properties that lead to the development of new therapeutic agents. Results: A bacterial strain was isolated from tumors located in the stem of Pinus patula, and it was identified as Pseudomonas cedrina. Extracts from biomass and broth of P. cedrina were obtained with chloroform:methanol (1:1). Only biomass extracts exhibited antiproliferative activity against human tumor cell lines of cervix (HeLa), lung (A-549), and breast (HBL-100). In addition, a biomass extract from P. cedrina was fractioned by silica gel column chromatography and two diketopiperazines were isolated: cyclo-(L-Prolyl-L-Valine) and cyclo-(L-Leucyl-L-Proline). Conclusions: This is the first report on the association of P. cedrina with the stems of P. patula in Mexico and the antiproliferative activity of extracts from this species of bacteria against human solid tumor cell lines.

Use of modified Richards model to predict isothermal and non-isothermal microbial growth

Abstract Mathematical models are often used to predict microbial growth in food products. An important class of these models involves the adaptation of classical sigmoid functions, such as the Gompertz and logistic functions. This study aimed to validate the use of the modified Richards model in various situations, which have not previously been tested. The model was obtained through solving a system of two differential equations and could be applied to both isothermal and non-isothermal environments. To test and validate this model, we used published datasets containing data for the growth of Pseudomonas spp. in fish products. The results obtained after fitting the model showed that it could be effectively used to describe and predict the Pseudomonas growth curves under various temperature regimens. However, the influence of the shape parameter on the growth curve is an issue that needs further evaluation.

Carbazole degradation in the soil microcosm by tropical bacterial strains

In a previous study, three bacterial strains isolated from tropical hydrocarbon-contaminated soils and phylogenetically identified as Achromobacter sp. strain SL1, Pseudomonas sp. strain SL4 and Microbacterium esteraromaticum strain SL6 displayed angular dioxygenation and mineralization of carbazole in batch cultures. In this study, the ability of these isolates to survive and enhance carbazole degradation in soil were tested in field-moist microcosms. Strain SL4 had the highest survival rate (1.8 x 107 cfu/g) after 30 days of incubation in sterilized soil, while there was a decrease in population density in native (unsterilized) soil when compared with the initial population. Gas chromatographic analysis after 30 days of incubation showed that in sterilized soil amended with carbazole (100 mg/kg), 66.96, 82.15 and 68.54% were degraded by strains SL1, SL4 and SL6, respectively, with rates of degradation of 0.093, 0.114 and 0.095 mg kg−1 h−1. The combination of the three isolates as inoculum in sterilized soil degraded 87.13% carbazole at a rate of 0.121 mg kg−1 h−1. In native soil amended with carbazole (100 mg/kg), 91.64, 87.29 and 89.13% were degraded by strains SL1, SL4 and SL6 after 30 days of incubation, with rates of degradation of 0.127, 0.121 and 0.124 mg kg−1 h−1, respectively. This study successfully established the survivability (> 106 cfu/g detected after 30 days) and carbazole-degrading ability of these bacterial strains in soil, and highlights the potential of these isolates as seed for the bioremediation of carbazole-impacted environments.

Production of biocontrol traits by banana field fluorescent Pseudomonads and comparison with chemical fungicide.

Pseudomonas aeruginosa isolated from banana field rhizosphere produced different antifungal metabolites like bactriocin, hydrogen cyanide and siderophore. Bacteriocinogenic, siderophoregenic, and HCN rich broth of isolate inhibited the growth of phytopathogen like Aspergilus niger, Aspergilus flavus, Fusarium oxysporum and Alternaria alternata. The isolate exhibited more antifungal activity and comparatively low MIC vis-a-vis commonly used copper based systemic chemical fungicide;bil cop.

Evaluación de la coloración diferencial de fluorescencia modificada en Pseudomonas spp. aisladas de suelo / Evaluation of the modified flourescence staining differential on Pseudomonas spp. isolated from soil

Se evaluó la coloración diferencial de fluorescencia modificada en Pseudomonas spp. aisladas de suelos de cultivos agrícolas del estado Sucre, a fin de observar eventos microscópicos relacionados con el ciclo celular. Cada especie de Pseudomonas identificada bioquímicamente se sembró en caldos incubados a temperatura ambiente, aerobiosis, durante 15, 20, 30 y 45 minutos, y 1, 24, 48 y 72 horas; luego, se elaboraron y colorearon los extendidos. En las 24 cepas de Pseudomonas identificadas, P. mendocina (41,67 por ciento), P. aeruginosa (37,50 por ciento) y P. putida (20,83 por ciento), se observaron variaciones de tinción en los diferentes tiempos de incubación como verde, amarilla y anaranjada, fluorescentes y de baja fluorescencia. La coloración emplea naranja de acridina que se intercala al ADN, provocando fluorescencia verde, e interactúa con el ARN provocando fluorescencia anaranjada; el decolorante remueve el naranja de acridina no unido al material genético y la fluoresceína de sodio produce color amarillo en bacterias que retienen suficiente cantidad de naranja de acridina. Las variaciones de tinción citoplasmática en Pseudomonas spp., están asociadas a la cantidad de ARN y ADN presente en la célula de acuerdo a la fase de su ciclo celular.

The modified fluorescence staining differential was evaluated using Pseudomonas spp. isolated from cultivated agricultural soils in the State of Sucre, in order to observe microscopic events related to the cellular cycle. Each species of biochemically identified Pseudomonas was inoculated into a broth and incubated at room temperature, aerobiosis, for 15, 20, 30 and 45 minutes and 1, 24, 48 and 72 hours; then, slides were made and stained. For the 24 identified strains of Pseudomonas, P. mendocina (41.67 percent), P. aeruginosa (37.50 percent) and P. putida (20.83 percent), staining variations such as green, yellow and orange, fluorescent and low fluorescence were observed for the different incubation times. The stain uses acridine orange that interacts with DNA by intercalation, causing green fluorescence; it interacts with RNA by electrostatic attraction causing orange fluorescence; the alcohol-acetone decolorant removes the acridine orange not united with the genetic material and sodium fluorescein produces a yellow color in bacteria that retain a sufficient amount of acridine orange. Cytoplasmatic staining variations in Pseudomonas spp., are associated with the amount of RNA and DNA present in the cells according to the phase of their cellular cycle.

Detection of Pseudomonas and Flavobacterium species harbouring organophosphorus degrading elements from environment

The extensive pollution of natural ecosystems has occurred by organophosphorus pesticides, being used for improvement of crop production in agriculture. Biodegradation is interested in application of multifunctional bacteria containing genetical elements which specially degrade organophosphorus compounds. In this paper the detection of two bacteria species, Pseudomonas and Flavobacterium, which harbouring organophosphorus degrading elements from environmental samples is reported. Several resistant strains isolated from different cultures that previously were cultivated with related sources such as soils and waters. These bacteria had been isolated from organophosphorus enriched mineral solutions, and following inoculation, visible colonies were observed on mineral and MacConkey's agar medium. The resistant bacteria were identified by conventional procedures and monitored with certain properties like stability, tolerance, resistance to organophosphorus compounds and different antibiotics. The genetical elements for organophosphate degradation were confirmed by adding acridine orange to culture of resistant strains which could delete these capabilities. Fifty strains were optimally grown in presence of three classes of organophophoruses like guthion, dimethoate and methyl parathion with concentrations of 2.5, 4, and 8 gl[-1] respectively. The gram-negative bacteria were identified using conventional diagnostic procedures, as Pseudomonas and Flavobacterium species. These strains were harbouring Organophosphorus degrading elements which were deleted by acridine orange as mutagen. Also, most of these bacteria were resistant to different antibiotics that used as biomarkers in discrimination of sensitive strains to organophosphoruses. The genetical elements such as resistance to organophosphoruses and antibiotics were transferred to the sensitive bacteria by matting technique and cured as multifunctional organisms which had high capability for various organophosphoruses. The multi-degrading strains might be suggested as useful tools for detoxification of harmful organophosphoruses in agriculture

Evaluación de la actividad desulfurizadora de aislados nativos de Pseudomonas spp. en presencia de hidrocarburo / Desulfurization activity evaluation of native strains of Pseudomonas spp. in the presence of hydrocarbon

El principal inconveniente en la combustión de los hidrocarburos es la conversión del azufre y el nitrógeno a sus respectivos óxidos, los cuales participan en la formación de lluvia acida y deterioran el medio ambiente e infraestructuras. La remoción de azufre a partir de compuestos órgano-azufrados mediante el uso de microorganismos ha surgido como una alternativa frente al proceso catalítico de hidrodesulfurización (HDS). En el presente trabajo se evaluó la actividad desulfurizadora de veintitrés aislados nativos de Pseudomonas spp. sobre dibenzotiofeno (DBT), usando un sistema de fermentación con igual proporción de fase acuosa y orgánica (n-hexano) en presencia de oleato de etanolamina. Los aislados 02,05 y 06 conservaron su viabilidad en este medio y presentaron una remoción de azufre entre 6,0 y 9,4%, generando los metabolitos DBT-sulfona, DBT-sulfóxido, 2-hidroxibifenilo (2-HBP) y sulfato presentes en la ruta metabólica 4S. Con estos aislados se evaluó la actividad desulfurizadora sobre keroseno y se observó una remoción de azufre entre 19,9 y 62,6% y una disminución del poder calorífico entre 0,45 y 5,55%.

The main difficulty with fossil fuel combustión lies in sulphur and nitrogen becoming converted to their respective oxides, forming part of the acid rain which deteriorates the environment and infrastructure. Removing sulphur from organo-sulfur compounds by using micro-organisms has become an alternative to hydrodesulphurisation (HDS). Twenty-three Pseudomonas spp. native strains' desulphurisation activity on dibenzothiophene (DBT) was evaluated by using a fermentation system having equal proportions of aqueous and organic (n-hexane) phases in the presence of ethanolamine oléate. The 02, 05 and 06 strains maintained their viability in this médium, presenting 6,0% to 9,4% sulphur removal, producing DBT-sulphone, DBT-sulphoxide, 2-hydroxybiphenyl (2-HBP) metabolites and sulphate belonging to the 4S pathway. These native strains' desulphurisation activity was evaluated on kerosene, presenting 19,9% to 62,2% sulphur removal having 0,45% to 5,55% calorific power loss.