Revision de Literatura Cientifica....

Articulo 1:Characterisation and application of glycanases secreted by Aspergillus terreus CCMI 498 and Trichoderma viride CCMI 84 for enzymatic deinking of mixed office wastepaper

Abstract:Two enzymatic extracts obtained from xylan-grown Aspergillus terreus CCMI 498 and cellulose-grown Trichoderma viride CCMI 84 were characterised for different glycanase activities. Both strains produce extracellular endoxylanase and endoglucanase enzymes. The enzymes optimal activity was found in the temperature range of 45–60 °C. Endoglucanase systems show identical activity profiles towards temperature, regardless of the strain and inducing substrate. Conversely, the endoxylanases produced by both strains showed maximal activity at different pH values (from 4.5 to 5.5), being the more acidic xylanase produced by T. viride grown on cellulose. The endoglucanase activities have an optimum pH at 4.5–5.0. The endoxylanase and endoglucanase activities exhibited high stability at 50 °C and pH 5.0. Mannanase, β-xylosidase, and amylase activities were also found, being the first two activities only present for T. viride extract. These two enzymatic extracts were used for mixed office wastepaper (MOW) deinking. When the enzymatic extract from T. viride was used, a further increase of 24% in ink removal was obtained by comparison with the control. Both enzymes contributed to the improvement of the paper strength properties and the obtained results clearly indicate that the effective use of enzymes for deinking can also contribute to the pulp and paper properties improvement.


Referencia:

S. Marquesa, H. Palab, L. Alvesa, M. T. Amaral-Collaçoa, F. M. Gamab and F. M. Gírio

a. Unidade de Fisiologia Microbiana e Bioprocessos, Departamento de Biotecnologia, INETI, Estrada do Paço do Lumiar 22, 1649-038, Lisbon, Portugal

b. Centro de Engenharia Biológica-IBQF, Universidade do Minho, Largo do Paço, 4719, Braga, Portugal

Received 21 December 2001;
revised 5 June 2002;
accepted 22 July 2002.
Available online 14 November 2002.

Article 2:Involvement of granulysin-producing T-cells in the development of superficial microbial folliculitis.

Abstract:
Granulysin is a recently identified antimicrobial protein expressed by cytotoxic T cells, NK cells and NKT cells. It is shown that granulysin contributes to defense mechanism against mycobacterial infection. Superficial microbial folliculitis is a common skin disease. In a previous report we could show, that as a first line of defense, alpha-defensin (human neutrophil peptides) and beta-defensin (human beta-defensin-2) were expressed in infiltrating neutrophils and lesional epidermal keratinocytes respectively in superficial folliculitis. As we also observed many infiltrating lymphocytes in lesional dermis, we hypothesized that infiltrating lymphocytes may possess antimicrobial substances such as granulysin and play a role in defense mechanism as a second line of defense. Seven specimens of superficial microbial folliculitis diagnosed clinically and histologically were examined by means of immunohistochemistry. To identify the phenotype of cells expressing granulysin, laser confocal microscopic examination was performed. Dense lymphoid cell infiltration was observed in pustules and perivascular regions. A large number of these lymphoid cells were positive for granulysin. The phenotype of cells consisted of CD3+T cells, CD8+T cells and UCHL-1+ T cells. CD20+ cells and CD56+cells were not observed. Laser confocal laser microscopic examination showed that the lymphocytes producing granulysin were CD3+, CD4+ T cells but not CD8+ T cells. We showed that many granulysin-bearing T cells infiltrated into affected follicles and perilesional dermis in superficial microbial folliculitis. However, few granulysin positve lymphoid cells were observed in sterile pustular lesions. Our observation indicated that adaptive immunity such as granulysin, lymphocyte-produced antimicrobial protein may play an important role in cutaneous defense mechanism.

reference:

Oono, Morizane,Yamasaki,Shirafuji,Akiyama,Iwatsuki, K.1
Journal of Investigative Dermatology; Nov2004, Vol. 123 Issue 5, pA87-A97, 11p

Articulo 3: Arsenic and Selenium in Microbial Metabolism.

Abstract: Arsenic and selenium are readily metabolized by prokaryotes, participating in a full range of metabolic functions including assimilation, methylation, detoxification, and anaerobic respiration. Arsenic speciation and mobility is affected by microbes through oxidation/reduction reactions as part of resistance and respiratory processes. A robust arsenic cycle has been demonstrated in diverse environments. Respiratory arsenate reductases, arsenic methyltransferases, and new components in arsenic resistance have been recently described. The requirement for selenium stems primarily from its incorporation into selenocysteine and its function in selenoenzymes. Selenium oxyanions can serve as an electron acceptor in anaerobic respiration, forming distinct nanoparticles of elemental selenium that may be enriched in ⁷⁶Se. The biogenesis of selenoproteins has been elucidated, and selenium methyltransferases and a respiratory selenate reductase have also been described. This review highlights recent advances in ecology, biochemistry, and molecular biology and provides a prelude to the impact of genomics studies.

Reference:
Stolz, John F.1 stolz@duq.edu, Basu, Partha2 basu@duq.edu, Santini, Joanne M.3 j.santini@ucl.ac.uk, Oremland, Ronald S.4 roremlan@usgs.gov
Annual Review of Microbiology; 2006, Vol. 60 Issue 1, p107-130, 24pvances in ecology, biochemistry, and molecular biology and provides a prelude to the impact of genomics studies.


“Juro, en mi honor que no he incurrido en actos de deshonestidad académica en la preparación del trabajo que hoy someto.”