Biosorption of Cd, Zn and Cu by Sargassum sp. waste biomass

Biosorption is becoming an important component in the integrated approach to the treatment of aqueous effluents. The economics of biomass technical applications are improved by using waste biomass instead of purposely-produced biomass. Biomass derived from an alginate extraction industry - Sargassum sp. - was examined for its ability to function as a biosorbent for metals such as cadmium, zinc and copper. For use in column applications, biomass should be immobilized. To the algae reinforcement, the biomass was embedded in polyethleneimine (PEI), followed by glutaraldehyde crosslinking. Equilibrium Zn and Cu isotherms were analysed using the immobilization ratio that showed the best Cd performance. Either Freundlich or Langmuir models can describe the passive biosorption equilibrium of cadmium, zinc and cooper. The preference for this series of metals by the biomass was found to be Cd > Zn > Cu, with maximum uptake values of 157.8, 118.5 and 77.4 mg/g dry weight biomass for Cd, Zn and Cu. respectively. The metal binding capacity by non-living biomass is an important quality for industrial use.     

Synthesis and in vitro anti Mycobacterium tuberculosis activity of a series of phthalimide derivatives

New phthalimide derivatives were easily prepared through condensation of phthalic anhydride and selected amines with variable yields (70–90%). All compounds (3a–l) were evaluated against Mycobacterium tuberculosis H₃₇Rv using Alamar Blue susceptibility. The compounds 3c, 3i, and 3l have the minimum inhibitory concentrations (MICs) of 3.9, 7.8, and 5.0 μg/mL, respectively, and could be considered new lead compounds in the treatment of tuberculosis and multi-drug resistant tuberculosis.     

Mucosal layers and related nerve fibres in non-chagasic and chagasic human colon—a quantitative immunohistochemical study

Chagasic megacolon is accompanied by extensive myenteric and, simultaneously, moderate submucosal neuron loss. Here, we examined changes of the innervation pattern of the lamina propria (LP) and muscularis mucosae (MM). Two alternating sets of cryosections were taken from seven non-chagasic colonic and seven chagasic megacolonic specimens (the latter included both the dilated megacolonic and the non-dilated transitional oral and anal zones) and were immunohistochemically triple-stained for smooth-muscle actin (SMA), synaptophysin (SYN) and glial acid protein S100 and, alternatively, for SMA, vasoactive intestinal peptide (VIP) and somatostatin (SOM). Subsequent image analysis and statistical evaluation of nervous tissue profile areas revealed that, in LP, the most extreme differences (i.e. increase in thickness or decrease in nerve, glia and muscle tissue profile area, respectively) compared with control values occurred in the dilated megacolonic zone itself. In contrast, the most extreme differences in the MM were in the anal-to-megacolonic zone (except the profile area of muscle tissue, which was lowest in the megacolonic zone). This parallels our previous results in the external muscle coat. A partial and selective survival of VIP-immunoreactive in contrast to SOM-immunoreactive nerve fibres was observed in both mucosal layers investigated. Thus, VIPergic nerve elements might be crucial for the maintenance of the mucosal barrier. The differential changes of neural tissue parameters in LP and MM might reflect a multifactorial rather than a pure neurogenic development of megacolon in chronic Chagas’ disease.     

Localization of Endo-Oligopeptidase (EC 3.4.22.19) in the Rat Nervous Tissue

The subcellular and regional distribution of endo-oligopeptidase (EC 3.4.22.19), an enzyme capable of generating enkephalin by single cleavage from enkephalin-containing peptides, was determined by an enzymatic assay using metorphamide and by immunochemical techniques in the CNS of the rat. The rat CNS contains a membrane-associated form of endo-oligopeptidase, an enzyme predominantly associated with the soluble fraction of brain homogenates. Subcellular fractionation showed that approximately 17% of the total activity of the enzyme is associated with membrane fractions including synaptosomes. Synaptosomal membranes were prepared from neocortex, striatum, hypothalamus, medulla, spinal cord, and cerebellum. The amount of EC 3.4.22.19 activity solubilized by 3-[( 3-cholamidopropyl]dimethylammonio)-1-propanesulfonate from synaptosomal membranes was similar in neocortex, striatum, and hypothalamus, being three- to 10-fold greater than in spinal cord, cerebellum, and medulla. A polyclonal antibody exhibiting high affinity for endo-oligopeptidase was raised in rabbits against the purified rat brain enzyme and used to localize endo-oligopeptidase by Western blotting and by immunoperoxidase techniques. A strong band corresponding to the Mr of EC 3.4.22.19 was found in solubilized proteins obtained from synaptosomal membranes prepared from hypothalamus, neocortex, and striatum when subjected to Western blotting. The immunohistochemical localization of endo-oligopeptidase indicated that the immunoreactivity was confined to gray matter in regions known to be rich in peptide-containing neurons such as the striatum. In the cerebellum, a region poor in peptides, no staining could be detected. The nonuniform distribution of endo-oligopeptidase in rat brain suggests a role in neurotransmitter processing in the CNS.     

Combined submerged and solid substrate fermentation for the bioconversion of lignocellulose

A novel two-stage bioreactor has been designed for a combined submerged (SF) and solid substrate fermentation (SSF) of wheat straw. The straw was pretreated with steam, and cellulases from the culture fluid of Trichoderma reesei were adsorbed on it for increased bioconvertibility. SSF was conducted in the top part of the bioreactor by inoculating the straw with a 36-h mycelial culture of T. reesei, or Coriolus versicolor. In the bottom part of the fermenter, Endomycopsis fibuliger was grown in SF. The SF liquor was recirculated through the SSF stage at 24 h intervals to remove glucose and other metabolites that may inhibit growth, and to maintain optimum moisture level and temperature. The removed glucose and other metabolites provided nutrients for the yeast in the SF stage. The combined fermentation resulted in overall higher biomass yield, increased bioconversion, increased cellulase production, and increased digestibility compared with single SSF or SF.     

An alkyl hydroperoxide reductase induced by oxidative stress in Salmonella typhimurium and Escherichia coli: genetic characterization and cloning of ahp

The ahp genes encoding the two proteins (F52a and C22) that make up an alkyl hydroperoxide reductase were mapped and cloned from Salmonella typhimurium and Escherichia coli. Two classes of oxidant-resistant ahp mutants which overexpress the two proteins were isolated. ahp-1 was isolated in a wild-type background and is dependent on oxyR, a positive regulator of defenses against oxidative stress. ahp-2 was isolated in an oxyR deletion background and is oxyR independent. Transposons linked to ahp-1 and ahp-2 or inserted in ahp mapped the genes to 13 min on the S. typhimurium chromosome, 59% linked to ent. Deletions of ahp obtained in both S. typhimurium and E. coli resulted in hypersensitivity to killing by cumene hydroperoxide (an alkyl hydroperoxide) and elimination of the proteins F52a and C22 from two-dimensional gels and immunoblots. ahp clones isolated from both S. typhimurium and E. coli complemented the cumene hydroperoxide sensitivity of the ahp deletion strains and restored expression of the F52a and C22 proteins. A cis-acting element required for oxyR-dependent, rpoH-independent heat shock induction of the F52a protein was present at the S. typhimurium but not the E. coli ahp locus.     

Recombinant Trypanosoma cruzi antigens and Chagas' disease diagnosis: analysis of a workshop

Abstract A workshop organized by the Ibero-American Project of Biotechnology evaluated the diagnostic potential of several cloned Trypanosoma cruzi recombinant antigens for Chagas' disease serodiagnosis. A set of recombinants, Antigen 2, Antigen 13, SAPA, H49, A13, JL5, JL7, JL8, JL9, and RA1 provided by three different South American laboratories were probed with a panel of 236 South American serum samples. Antigens JL7, H49, Antigen 2, and A13 scored as the best diagnostic recombinant reagents. The results suggested that the main advantage of using cloned peptides for chronic Chagas' disease diagnosis resided in their highly specific immunoreactive properties.     

Transfer of [14C] cholesterol and its metabolites between adult male and female worms of Schistosoma mansoni

Adult male and female worms of Schistosoma mansoni are able to incorporate [14C]cholesterol and convert it into several metabolites. Schistosomula on the other hand cannot convert the incorporated cholesterol. Male worms are able to transfer the [14C]cholesterol and labelled metabolites to female worms but labelled female worms can transfer cholesterol but are unable to transfer the conversion products of cholesterol to male worms. Uptake by female worms of labelled products shed by male worms seems to occur more efficiently in the presence of serum than in its absence.