Characterization of carbohydrate components of an unusual hydrogel formed by seed coats of Magonia pubescens (Tingui)

The influence of Tween 80 on laccase production by Pleurotus sajor-caju and the efficiency of crude enzyme broth in the removal of bisphenol-A

ABSTRACT: Bisphenol-A is currently considered an environmental pollutant, capable of interfering in the endocrine system of organisms and causing alterations in its development and reproductive system. An alternative method to the chemical treatment of this pollutant has been the use of oxidative enzymes, especially laccases produced by fungi. In order to reduce production costs, agro-industrial waste can be used in the culture medium composition. Nonionic surfactants, which are only slightly toxic to biological membranes, can be applied, as well as Tween 80, to facilitate the excretion of these enzymes into the culture medium. The objectives of this work were: a) characterize the immersion water of banana straw used in the formulation of the culture medium; b) evaluate laccase production by Pleurotus sajor-caju in culture medium with and without addition of Tween 80, through shaken flasks; c) evaluate the efficiency of the crude enzyme broth in degrading bisphenol-A. The shaken flasks were incubated at 30°C for 12 days. The immersion water had a C:N ratio of 13.8, ash percentage of 28.6%, and pH close to neutrality. The addition of Tween 80 on the culture medium (7.5%, m/v) yielded laccase activity and productivity values equal to 3,016.47 U L-1 and 502.7 U L-1 day-1, respectively. These values were 50 and 33.5 times higher than those obtained in the culture medium without addition of Tween 80 for laccase activity and productivity, respectively. The crude enzyme broth degraded 100% of bisphenol-A after 48 hours, regardless of concentration (500, 750 and 1,000 mg L-1).

Anti-bacterial activity of some Brazilian medicinal plants

Extracts from various organs of 25 plants of Brazilian traditional medicine were assayed with respect to their anti-bacterial activities against Escherichia coli, a susceptible strain of Staphylococcus aureus and two resistant strains of Staphylococcus aureus harbouring the efflux pumps NorA and MsrA. Amongst the 49 extracts studied, 14 presented anti-bacterial activity against Staphylococcus aureus, including the ethanolic extracts from the rhizome of Jatropha elliptica, from the stem barks of Schinus terebinthifolius and Erythrina mulungu, from the stems and leaves of Caesalpinia pyramidalis and Serjania lethalis, and from the stem bark and leaves of Lafoensia pacari. The classes of compounds present in the active extracts were determined as a preliminary step towards their bioactivity-guided separation. No extracts were active against Escherichia coli.

Microscopic and NMR analysis of the external coat from seeds of Magonia pubescens

•  The chemical composition and structure of the layers of the external coat and the three-dimensional organization of the gel during the swelling process are reported here for seeds of Magonia pubescens. •  Histochemical-light and scanning electron microscopy (SEM) were used in conjunction with CP-MAS (cross polarization - magic angle spinning: solid state) ¹³ C NMR spectroscopy to analyse the seed coat layers. •  M. pubescens seeds extrude a gel from the second of five regions of the external seed coat when immersed in water. This gel, visualized by SEM, had an extruded cylindrical, laminated structure. Staining revealed two anionic components in the cells of the second layer; the cytoplasm showed the presence of carbohydrates containing vicinal hydroxyl groups and at least some of these carbohydrates were acidic polysaccharides. Part of the β-linked glucan present in this layer was cellulosic material. Phenolic compounds were not detected in the second layer, but existed in other layers. Lignin and/or tannins were shown in the cell walls of the three innermost layers by CP-MAS ¹³ C NMR spectroscopy. •  The solid-state NMR technique had the advantage of being more sensitive and quantitative compared with light microscropy and might prove to be a useful tool in investigating cell components.