Lívia Cordi

Os Museus de História Natural atuam na preservação, investigação e comunicação científica. Os organismos preservados nas coleções representam a história dos seres que habitam ou já habitaram a Terra, além das informações associadas a eles que podem ser utilizadas para diferentes finalidades investigativas. Ainda, por meio de exposições e atividades educativas, “traduzem” o conhecimento gerado nas instituições de pesquisa ao público em geral. A proposta deste artigo é apresentar o Museu de Diversidade Biológica – MDBio, que tem como principal objetivo contribuir para o conhecimento da ciência e aproximar Universidade e Sociedade. O MDBio, abriga, além das coleções destinadas à pesquisa em diferentes áreas, uma exposição permanentemente aberta ao público, com salas temáticas que contemplam a biodiversidade brasileira. Assim, o público que visita o museu tem a oportunidade de conhecer uma grande diversidade de animais que vivem em diferentes tipos de ambientes, como a cidade das formigas. Como programa educativo, visando atender principalmente às escolas, oferece visitas monitoradas para professores, estudantes e o público em geral, de diferentes faixas etárias. Ainda, conta com atividades sobre a biodiversidade e preservação ambiental, como oficinas e exposições, empréstimo de coleções didáticas para escolas e conteúdo em mídias digitais. Desta forma, dialoga com o público, permitindo interação e troca de saberes e segue com seus objetivos de divulgação e educação científica em constante evolução, fomentando o respeito por esses ambientes e sua fauna e flora específicas.

In the present study, semi-purified laccase from Trametes versicolor was applied for the synthesis of silver nanoparticles, and the properties of the produced nanoparticles were characterized. All of the analyses of the spectra indicated silver nanoparticle formation. A complete characterization of the silver nanoparticles showed that a complex of silver nanoparticles and silver ions was produced, with the majority of the particles having a Ag2+ chemical structure. A hypothetical mechanistic scheme was proposed, suggesting that the main pathway that was used was the interaction of silver ions with the T1 site of laccase, producing silver nanoparticles with the concomitant inactivation of laccase activity and posterior complexing with silver ions.

Multi-wall carbon nanotubes (MWCNT) were functionalized with functional groups containing oxygen, mainly carboxylic groups (-COOH), through reaction with a mixture of H₂SO₄/HNO₃ (3:1 v/v). The oxidized multi-wall carbon nanotubes (MWCNTOOH) were used to prepare an effluent, 2 mg L⁻¹ in a saline solution of NaCl (0.9%), to study of remediation of MWCNTOOH in aqueous suspension by utilization of Escherichia coli. The suspensions of E. coli (4.5 × 10⁵ CFU mL⁻¹ and 4.5 × 10⁸ CFU mL⁻¹) in test tubes with MWCNTOOH effluent caused the precipitation of a large amount of MWCNTOOH and supernatant clearing. The scanning electron microscopy (SEM) analysis of the precipitate and supernatant showed the adhesion and interlace of MWCNTOOH in bacteria surface. Although the precipitate consist of a large quantity of MWCNTOOH and bacteria, it was verified their presence in the supernatant. The spread plate technique showed that MWCNTOOH caused no cellular death of E. coli in the supernatant.

The violet pigment violacein is an indole derivative, isolated mainly from bacteria of the genusChromobacterium, which exhibits important antitumoural, antimicrobial and antiparasitary properties. Furthermore, the formulation of violacein in different polymeric carriers developed so far offers alternative approaches to overcoming physiological barriers and undesirable physicochemical propertiesin vivo, thus improving its efficacy.

This paper reports an approach for quantification of Lactobacillus in fermented milk, grown in a selective medium (MRS agar), by use of digital colour images of Petri plates easily obtained by use of a flatbed scanner. A one-dimensional data vector was formed to characterize each digital image on the basis of the frequency-distribution curves of the red (R), green (G), and blue (B) colour values, and quantities derived from them, for example lightness (L), relative red (RR), relative green (RG), and relative blue (RB). The frequency distributions of hue, saturation, and intensity (HSI) were also calculated and included in the data vector used to describe each image. Multivariate non-linear modelling using the least-squares support vector machine (LS-SVM) and a linear model based on PLS regression were developed to relate the microbiological count and the frequency vector. Feasibly models were developed using the LS-SVM and errors were below than 10% for Lactobacillus quantification, indicating the proposed approach can be used for automatic counting of colonies.