Cintia Mariana Romero

Towards efficient biocatalysts: photo-immobilization of a lipase on novel lysozyme amyloid-like nanofibrils

Herein, we report the preparation and characterization of a new biocatalyst based on the photo-immobilization of a lipase onto hybrid protein:sugar nanofibrils. The nanofibrils are obtained through the aggregation of hen white egg lysozyme induced by the highly sulfated glycosaminoglycan heparin. The new hybrid nanomaterial could be easily functionalized using photochemical reaction to attach lipases through dityrosine covalent bonds. Compared to the free enzyme, the photo-immobilized lipase has better thermostability and enhanced resistance to non-conventional environment. Structural and morphological characterization of the nanofibrils shows that they are compatible with amyloid-like aggregates. In addition, the supramolecular arrangement of heparin and lysozyme within the building unit of the nanofibrils is also proposed. The procedure reported herein could be useful to design a new generation of insoluble biocatalyst by a single photo-click step which is definitely cleaner and faster than conventional chemical cross-linked procedures.

Biofilm inhibition activity of traditional medicinal plants from Northwestern Argentina against native pathogen and environmental microorganisms

INTRODUCTION: Plants have been commonly used in popular medicine of most cultures for the treatment of disease. The in vitro antimicrobial activity of certain Argentine plants used in traditional medicine has been reported. The aim of this study was to investigate the antimicrobial, anti-biofilm, and anti-cell adherence activities of native plants (Larrea divaricata, Tagetes minuta, Tessaria absinthioides, Lycium chilense, and Schinus fasciculatus) collected in northwestern Argentina. METHODS: The activities of the five plant species were evaluated in Bacillus strains and clinical strains of coagulase-negative Staphylococcus isolated from northwestern Argentina and identified by 16S rDNA. RESULT: Lycium chilense and Schinus fasciculatus were the most effective antimicrobial plant extracts (15.62µg/ml and 62.50µg/ml for Staphylococcus sp. Mcr1 and Bacillus sp. Mcn4, respectively). The highest (66%) anti-biofilm activity against Bacillus sp. Mcn4 was observed with T. absinthioides and L. divaricate extracts. The highest (68%) anti-biofilm activity against Staphylococcus sp. Mcr1 was observed with L. chilense extract. T. minuta, T. absinthioides, and L. divaricata showed percentages of anti-biofilm activity of between 55% and 62%. The anti-adherence effects of T. minuta and L. chilense observed in Bacillus sp. Mcn4 reflected a difference of only 22% and 10%, respectively, between anti-adherence and biofilm inhibition. Thus, the inhibition of biofilm could be related to cell adherence. In Staphylococcus sp. Mcr1, all plant extracts produced low anti-adherence percentages. CONCLUSION: These five species may represent a source of alternative drugs derived from plant extracts, based on ethnobotanical knowledge from northwest Argentina.

Endoglucanase and xylanase production by Bacillus sp. AR03 in co-culture

ABSTRACT The behavior of three isolates retrieved from different cellulolytic consortia, Bacillus sp. AR03, Paenibacillus sp. AR247 and Achromobacter sp. AR476-2, were examined individually and as co-cultures in order to evaluate their ability to produce extracellular cellulases and xylanases. Utilizing a peptone-based medium supplemented with carboxymethyl cellulose (CMC), an increase estimation of 1.30 and 1.50 times was obtained by the co-culture containing the strains AR03 and AR247, with respect to enzyme titles registered by their individual cultivation. On the contrary, the extracellular enzymatic production decreased during the co-cultivation of strain AR03 with the non-cellulolytic Achromobacter sp. AR476-2. The synergistic behavior observed through the combined cultivation of the strains AR03 and AR247 might be a consequence of the consumption by Paenibacillus sp. AR247 of the products of the CMC hydrolysis (i.e., cellobiose and/or cello-oligosaccharides), which were mostly generated by the cellulase producer Bacillus sp. AR03. The effect observed could be driven by the requirement to fulfill the nutritional supply from both strains on the substrate evaluated. These results would contribute to a better description of the degradation of the cellulose fraction of the plant cell walls in nature, expected to an efficient utilization of renewable sources.

Raw sugarcane bagasse as carbon source for xylanase production by Paenibacillus species: a potential degrader of agricultural wastes

Paenibacillus species isolated from a variety of natural sources have shown to be important glycoside hydrolases producers. These enzymes play a key role in bio-refining applications, as they are central biocatalysts for the processing of different types of polymers from vegetal biomass. Xylanase production by three native isolates belonging to the genus Paenibacillus was approached by utilizing mineral-based medium and agricultural by-products as a convenient source to produce biocatalysts suitable for their degradation. While varieties of alkali pretreated sugarcane bagasse were useful substrates for the strains from Paenibacillus genus evaluated, raw sugarcane bagasse was the most effective substrate for endoxylanase production by Paenibacillus sp. AR247. This strain was then selected to further improvement of its enzyme production by means of a two-step statistical approach. It was determined that the carbon source, provided as an inexpensive agro-waste, as well as phosphate and magnesium were the culture media components that most influenced the enzyme production, which was improved three times compared to the screening results.

Designing cross-linked xylanase aggregates for bioconversion of agroindustrial waste biomass towards potential production of nutraceuticals

Immobilized biocatalysts design has the potential to efficiently produce valuable bioproducts from lignocellulosic biomass. Among them, the carrier-free immobilization through the cross-linked enzyme aggregates technology is a simple and low-cost alternative. A two steps statistical approach was utilized to evaluate the synthesis of a cross-linked enzyme aggregate from a xylanolytic preparation, which was produced by Cohnella sp. AR92 grown in a peptone-based culture medium. The resulting immobilized biocatalyst, Xyl-CLEA, was significate more stable (25 to 45%) towards temperatures up to 50°C with respect to the free enzyme, and retained over 50% of its initial activity after 5 consecutive cycles of reuse. By means of infrared spectroscopy and electron microscopy, the Xyl-CLEA showed architectural features described as signature of type I and type II of protein aggregates. These, were the result of the simultaneous aggregation of a multiplicity of proteins from the crude enzymatic extract. The enzymatic activity was assessed using alkali pretreated sugar cane bagasse as substrate. Whereas the free enzymatic preparation released xylose as the main product, the immobilized xylanase produced xylooligosaccharides, thus showing that the immobilization procedure modified the potential application of the extracellular xylanase from Conhella sp. AR92.

Draft Genome Sequence of Achromobacter sp. Strain AR476-2, Isolated from a Cellulolytic Consortium

ABSTRACT Achromobacter sp. AR476-2 is a noncellulolytic strain previously isolated from a cellulolytic consortium selected from samples of insect gut. Its genome sequence could contribute to the unraveling of the complex interaction of microorganisms and enzymes involved in the biodegradation of lignocellulosic biomass in nature.

Fungal Nanotechnology: A New Approach Toward Efficient Biotechnology Application

Nanotechnology is a wide developing area of the biotechnology since the important applications of nanoparticles (NPs) in different technologies. The NPs produced by green technologies have many advantages such as greater surface area and high catalytic activity, in addition to providing a suitable contact between the metal salt and enzyme. Fungi secrete proteins, enzymes, and reducing agents which can be used for the synthesis of metal NPs from metal salts.

Direct Dna Amplification from Fall Armyworm (Lepidoptera: Noctuidae) Samples

The direct amplification by PCR of the DNA in tissue samples of eggs and neonate larvae of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) was accomplished, and it is a new alternative for DNA amplification from fall armyworm samples. This method is simple, fast, economic, and accelerates studies on this polyphagous pest. Se aplico la tecnica de PCR para amplificar el DNA directamente a partir de huevos y de larvas neonatas de Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). Esta es una nueva alternativa para la amplificacion del ADN de muestras del gusano cogollero. El metodo propuesto es simple, rapido, economico y agiliza los procedimientos para diversos estudios sobre esta plaga polifaga. View this article in BioOne

Hydrolytic and synthetic activities of esterases produced by Bacillus sp. A60 isolated from an oil contaminated soil

A novel esterase producer strain named Bacillus sp. A60 was isolated from a soil sample contaminated with hydrocarbons. It was found to belong to Bacillus subtilis species through morphological, biochemical and 16S rRNA gene sequence analyses. This strain which can tolerate 15% (w/v) NaCl and growth at 55°C, produced an interesting esterase activity in Luria-Bertani medium. Two different molecular weight esterase activities were detected in zymographic assays. Culture supernatant and whole cells showed specific hydrolytic activities of 2.67 ± 0.11 U/mg of protein and 7.07 ± 0.09 U/mg of dry weight, respectively. Concerning ethyl acetate production, conversions of 88.00 ± 0 and 55.58 ± 0.78% were obtained with culture supernatant entrapped in polyacrylamine gel and whole cells, respectively. In addition, the effect of different concentration of LB medium components on both growth and extracellular esterase hydrolytic activity was also discussed. Key words : Bacillus , esterases, hydrolytic activity, synthetic activity, ethyl acetate.