Glycosaminoglycan Binding Facilitates Entry of a Bacterial Pathogen into Central Nervous Systems

Certain microbes invade brain microvascular endothelial cells (BMECs) to breach the blood-brain barrier (BBB) and establish central nervous system (CNS) infection. Here we use the leading meningitis pathogen group B Streptococcus (GBS) together with insect and mammalian infection models to probe a potential role of glycosaminoglycan (GAG) interactions in the pathogenesis of CNS entry. Site-directed mutagenesis of a GAG-binding domain of the surface GBS alpha C protein impeded GBS penetration of the Drosophila BBB in vivo and diminished GBS adherence to and invasion of human BMECs in vitro. Conversely, genetic impairment of GAG expression in flies or mice reduced GBS dissemination into the brain. These complementary approaches identify a role for bacterial-GAG interactions in the pathogenesis of CNS infection. Our results also highlight how the simpler yet genetically conserved Drosophila GAG pathways can provide a model organism to screen candidate molecules that can interrupt pathogen-GAG interactions for future therapeutic applications

Production and purification of alkaline xylanases

This work investigated more than 500 colonies with xylanolytic activity which were able to grow in a medium containing corn xylan as the only carbon source. Out of the 500 colonies, 22 microorganisms were also able to grow in birchwood xylan and were cellulase-free producers. The xylanase activity was studied at pH 10.0 and pH 5.0. It was observed that the three best producers of alkaline xylanase yielded enzyme levels in the range of 2.6 to 4.0 U/ml. Enzyme levels of 1.0 to 1.25 U/ml were achieved by four other microorganisms. Conversely, there were three microorganisms that produced a xylanase which was mostly active at pH 5.0. There was just one microorganism able to produce an enzyme active at pH 10.0. The alkaline xylanases from crude fermentation broth were extracted in aqueous two-phase systems (ATPS) composed of 16% polyethyleneglycol (PEG 6000) and 8% phosphate salt. A purification factor of 57 and a 41% yield of enzyme activity were achieved for the system containing 16% PEG 6000, 8% K2HPO4 and 12% NaCl. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.681495

Xylan-hydrolyzing enzyme system from Bacillus pumilus CBMAI 0008 and its effects on Eucalyptus grandis kraft pulp for pulp bleaching improvement

The extracellular productions of beta-xylanase, beta-xylosidase, beta-glucosidase, beta-mannanase, arabinosidase, alpha-glucuronidase, alpha-galactosidase and Fpase from Bacillus pumilus CBMAI 0008 were investigated with three different xylan sources as substrate. The enzymatic profiles on birchwood, Eucalyptus grandis and oat were studied at alkaline and acidic pH conditions. B. pumilus CBMAI 0008 grown on the three carbon sources produced mainly beta-xylanase. At pH 10, the levels of xylanase were 328, 160 and 136 U/ml, for birch, oat and E grandis, respectively. beta-Mannanase production was induced on E grandis (5 U/ml) and arabinofuranosidase on oat (5 U/ml). Although small quantities of alpha-glucuronidase had been produced at pH 10, activity at pH 4.8 was 1.5 U/ml, higher than observed for Aspergillus sp. in literature reports. Preliminary assays carried out on E grandis kraft pulp from an industrial paper mill (RIPASA S.A. Celulose e Papel, Limeira, SP, Brazil) showed a reduction of 0.3% of chlorine use in the pulp treated with the enzymes, resulting in increased brightness, compared to conventional bleaching. The enzymes were more efficient if applied before the initial bleaching sequence, in a non-pre-oxygenated pulp. (C) 2002 Elsevier Science Ltd. All rights reserved.88191