16 research outputs found
Fucoidan-degrading fungal strains: screening, morphometric evaluation, and influence of medium composition
Ten different fungal strains from the genus Aspergillus, Penicillium, and Mucor
were screened for fucoidan hydrolyzing ability aiming to find microorganisms able to
produce sulfated fucan-degrading enzymes. Screening was carried out by measuring the
strains kinetic and morphometric behavior over plate assays using Laminaria japonica
fucoidan as only carbon source, testing three nitrogen sources (urea, peptone, and sodium
nitrate). The selected fungal strains were subsequently used in submerged fermentations,
which were performed for (1) selection of the strains able to growth over fucoidan medium
and (2) media selection, testing the synergy of fucoidan with other sugars for inducing high
enzyme titles. Radial expansion and hyphae parameters were observed for Aspergillus niger
PSH, Mucor sp. 3P, and Penicillium purpurogenum GH2 grown only over fucoidan-urea
medium. A. niger PSH showed the maximum enzymatic activity values, which were
significantly different (p<0.05) from those achieved by the other selected fungi. Sucrose
addition to fucoidan media proportioned the highest fucoidanase activity values for this
fungal strain. This research allowed establishing optimal conditions for metabolites
synthesis by fungal stains able to act toward fucoidan ramified matrix.Mexican
Science and Technology Council (CONACYT
Current Understanding on Adhesion and Biofilm Development in Actinobacteria
Biofilm formation and microbial adhesion are two related and complex phenomena. These phenomena are known to play an important role in microbial life and various functions with positive and negative aspects. Actinobacteria have wide distribution in aquatic and terrestrial ecosystems. This phylum is very large and diverse and contains two important genera Streptomyces and Mycobacteria. The genus Streptomyces is the most biotechnologically important, while the genus Mycobacteria contains the pathogenic species of Mycobacteriaceae. According to the literature, the majority of studies carried out on actinomycetes are focused on the detection of new molecules. Despite the well-known diversity and metabolic activities, less attention has been paid to this phylum. Research on adhesion and biofilm formation is not well developed. In the present review, an attempt has been made to review the literature available on the different aspects on biofilm formation and adhesion of Actinobacteria. We focus especially on the genus Streptomyces. Furthermore, a brief overview about the molecules and structures involved in the adhesion phenomenon in the most relevant genus is summarized. We mention the mechanisms of quorum sensing and quorum quenching because of their direct association with biofilm formation
Sulfated fucan as support for antibiotic immobilization
Xylofucoglucuronan from Spatoglossum schröederi algae was tested as a support for antibiotic immobilization. The polysaccharide (20 mg in 6 ml) was first activated using carbodiimide, 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide methiodide (20 mg in 2 ml), under stirring for 1 h at 25ºC and pH from 4.5 to 5.0. After adjusting the pH to 8.0, either gentamicin or amikacin (62.5 mg in 1.25 ml) was then immobilized on this chemically modified polysaccharide with shaking for 24 h in a cold room. Infrared spectra of the activated carbodiimide xylofucoglucuronan showed two bands to carbonyl (C = O at 1647.9 and 1700.7 cm-1) and to amide (C<FONT FACE=Symbol>Ý</FONT>-NH2) groups (1662.8 and 1714.0 cm-1). Microbial characterization of the derivatives was carried out by the disk diffusion method using Staphylococcus aureus or Klebsiella pneumoniae incorporated in Müller Hinton medium. Inhibition halos of bacterial growth were observed for the antibiotics immobilized on this sulfated heteropolysaccharide before and after dialysis. However, the halos resulting from the samples after dialysis were much smaller, suggesting that dialysis removed either non-covalently bound antibiotic or other small molecules. In contrast, bacterial growth was not inhibited by either xylofucoglucuronan or its activated form or by gentamicin or amikacin after dialysis. An additional experiment was carried out which demonstrated that the sulfated heteropolysaccharide was hydrolyzed by the microorganism. Therefore, the antibiotic immobilized on xylofucoglucuronan can be proposed as a controlled drug delivery system. Furthermore, this sulfated heteropolysaccharide can be extracted easily from sea algae Spatoglossum schröederi