Carolina Barbosa Malafaia

Purification, characterization and antibacterial potential of a lectin isolated from Apuleia leiocarpa seeds

Apuleia leiocarpa is a tree found in Caatinga that has great value in the timber industry. Lectins are carbohydrate-binding proteins with several biotechnological applications. This study shows the isolation, characterization, and antibacterial activity of A. leiocarpa seed lectin (ApulSL). The lectin was chromatographically isolated from a crude extract (in 150 mM NaCl) by using a chitin column. ApulSL adsorbed to the matrix and was eluted using 1.0 M acetic acid. Native ApulSL was characterized as a 55.8-kDa acidic protein. SDS-PAGE showed three polypeptide bands, whereas two-dimensional electrophoresis revealed four spots. The peptides detected by MALDI TOF/TOF did not show sufficient homology (<30%) with the database proteins. Circular dichroism spectroscopy suggested a disordered conformational structure, and fluorescence spectrum showed the presence of tyrosine residues in the hydrophobic core. The hemagglutinating activity of ApulSL was present even after heating to 100 °C, was Mn(2+)-dependent, and inhibited by N-acetylglucosamine, D(-)-arabinose, and azocasein. ApulSL demonstrated bacteriostatic and bactericide effects on gram-positive and gram-negative species, being more effective against three varieties of Xanthomonas campestris (MIC ranging from 11.2 to 22.5 μg/mL and MBC of 22.5 μg/mL). The results of this study reinforce the importance of biochemical prospecting of Caatinga by revealing the antibacterial potential of ApulSL.

Perspectives on the production, structural characteristics and potential applications of bioplastics derived from polyhydroxyalkanoates

Since the last two decades, the use of synthetic materials has increased and become more frequent in this capitalist system. Polymers used as raw materials are usually disposed very rapidly and considered serious damages when they return to the environment. Because of this behaviour, there was an increasing in the global awareness by minimizing the waste generated, in addition to the scientific community concern for technological alternatives to solve this problem. Alternatively, biodegradable polymers are attracting special interest due to their inherent properties, which are similar to the ones of the conventional plastics. Bioplastics covers plastics made from renewable resources, including plastics that biodegrade under controlled conditions at the end of their use phase. Polyhydroxyalkanoates (PHAs) are polyesters composed of hydroxy acids, synthesized by a variety of microorganisms as intracellular carbon and energy storage. These environmentally friendly biopolymers have excellent potential in domestic, agricultural, industrial and medical field, however their production on a large scale is still limited. This review considered the most recent scientific publications on the production of bioplastics based on PHAs, their structural characteristics and the exploitation of different renewable sources of raw materials. In addition, there were also considered the main biotechnological applications of these biopolymers.

Selection of a protein solubilization method suitable for phytopathogenic bacteria: a proteomics approach.

BackgroundFinding the best extraction method of proteins from lysed cells is the key step for detection and identification in all proteomics applications. These are important to complement the knowledge about the mechanisms of interaction between plants and phytopathogens causing major economic losses. To develop an optimized extraction protocol, strains of Acidovorax citrulli, Pectobacterium carotovorum subsp. carotovorum and Ralstonia solanacearum were used as representative cells in the study of phytopathogenic bacteria. This study aims to compare four different protein extraction methods, including: Trizol, Phenol, Centrifugation and Lysis in order to determine which are more suitable for proteomic studies using as parameters the quantity and quality of extracted proteins observed in two-dimensional gels.ResultsThe bacteria studied showed different results among the tested methods. The Lysis method was more efficient for P. carotovorum subsp. carotovorum and R. solanacearum phytobacteria, as well as simple and fast, while for A. citrulli, the Centrifugation method was the best. This evaluation is based on results obtained in polyacrylamide gels that presented a greater abundance of spots and clearer and more consistent strips as detected by two-dimensional gels.ConclusionsThese results attest to the adequacy of these proteins extraction methods for proteomic studies.

Evaluation of the Resistance and Differential Induction of Chitinases in Tomato in Response to Inoculation with Fusarium oxysporum f. sp.lycopersici

Evaluation of the Resistance and Differential Induction of Chitinases in Tomato in Response to Inoculation with Fusarium oxysporum f. sp.lycopersici Fusarium oxysporum f. sp. lycopersici (FOL) causes Fusarium wilt in tomato, a disease that significantly affects its production. This project investigated the response of different tomato genotypes to Fusarium wilt, aiming at selecting sources of resistance, as well as identifying the differential chitinase secretion during infection between resistant and susceptible cultivars. Results show that the BHRS cultivar proved to be resistant to the disease and there was increased chitinolytic activity in the roots of this genotype six days after inoculation (dai).

Two-dimensional profiling of Xanthomonas campestris pv. viticola proteins extracted by four different methods

An efficient method for protein extraction is a prerequisite for the successful implementation of proteomics, which is being used as a tool in the study of the interaction between plants and phytopathogens. With the objective to optimize a method of protein extraction for proteomic analysis of the phytobacterium Xanthomonas campestris pv. viticola , the efficiency of four methodologies were compared, based on the two-dimensional gel electrophoresis profile (2D-PAGE). Trizol ® , phenol, centrifugation and lysis methods were tested and through quantitative and qualitative analysis, the most suitable method to obtain high-quality protein was selected. All methodologies enabled the extraction of a significant amount of proteins; nevertheless, the centrifugation method allowed obtaining the highest concentration of solubilized proteins. However, the analysis of the 2D-PAGE gel images revealed a larger number of spots in the lysis method when compared to the others. Taking into consideration the quality of the results and the practical advantages of the lysis method, this is recommended as the best option for total protein extraction of X. campestris pv. viticola for proteomic studies. Keywords: Bacterial canker, Vitis vinifera , proteomics, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional gel electrophoresis (2D-PAGE). African Journal of Biotechnology , Vol 13(31) 3531-3537

Biofilm formation by Xanthomonas campestris pv. v iticola affected by abiotic surfaces and culture media

Biofilms are dense surface-associated communities formed by microorganisms. Formation of these structures by the plant pathogenic bacterium Xanthomonas campestris pv. viticola (bacterial canker of grapevine) had not previously been studied. The ability of seven strains of this bacterium to adhere to abiotic surfaces and to form biofilms in vitro was evaluated under different conditions. The surfaces tested were polystyrene and glass using microtiter plates and tubes, respectively. Four liquid culture media were used, nutrient-dextrose-yeast extract (NYD), yeast extract-dextrose-calcium carbonate (YDC), Kado 523 (KADO) and Luria-Bertani (LB). The biofilm architecture was examined by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Seven strains adhered to polystyrene in the microtiter plates and formed biofilms in all culture media at weak, moderate, and strong levels. In glass tubes, only strains Xcv229 and Xcv158 formed biofilms. SEM of Xcv229 and Xcv158 revealed typical biofilm architectures. CLSM showed that only Xcv229 formed an initial matrix structure characteristic of biofilms. The X. campestris pv. viticola strains exhibited different levels of biofilm formation in different culture media, of which LB and KADO were the best. Therefore, bacterial growth in polystyrene microtiter plates using LB and KADO media is a good qualitative method for the detection of biofilms of this pathogen.

Effects of Caatinga Plant Extracts in Planktonic Growth and Biofilm Formation in Ralstonia solanacearum

This study describes the first antibiofilm and antibacterial screening for plants from Caatinga against Ralstonia solanacearum, a causal agent of bacterial wilt that presents serious difficulties in control. There were prepared 22 aqueous extracts of plants collected in the Vale do Catimbau—PE, Brazil. The potential antibacterial activity was evaluated by absorbance in OD600 and the antibiofilm activity through the crystal violet method, both of them performed in microplate against isolates of R. solanacearum biofilm formers. The results of the screening showed that Jacaranda rugosa presented antimicrobial activity higher than 90%, while Harpochilus neesianus and Myroxylon peruiferum presented antibiofilm activity higher than 50% for all tested isolates. However, Croton heliotropiifolius showed both the activities, being thus very promising for application in the control of this phytopathogen. The search for viable alternatives to the development of new bioactive compounds safe for the environment, humans, and animals from an adverse and scarce environment such as the Caatinga and encouraged us to find plants that produce effective metabolites against phytopathogenic microorganisms. This in vitro screening is important to guide the development of new products in addition to guide research studies of bioactive compounds.