The aim of this study was to determine the antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20 against several micro-organisms, ...including Gram-positive and Gram-negative bacteria, yeasts and filamentous fungi. Antimicrobial and antiadhesive activities were determined using the microdilution method in 96-well culture plates. The biosurfactant showed antimicrobial activity against all the micro-organisms assayed, and for twelve of the eighteen micro-organisms (including the pathogenic Candida albicans, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus agalactiae), the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were achieved for biosurfactant concentrations between 25 and 50 mg ml⁻¹. Furthermore, the biosurfactant showed antiadhesive activity against most of the micro-organisms evaluated. As far as we know, this is the first compilation of data on antimicrobial and antiadhesive activities of biosurfactants obtained from lactobacilli against such a broad group of micro-organisms. Although the antiadhesive activity of biosurfactants isolated from lactic acid bacteria has been widely reported, their antimicrobial activity is quite unusual and has been described only in a few strains. The results obtained in this study regarding the antimicrobial and antiadhesive properties of this biosurfactant opens future prospects for its use against micro-organisms responsible for diseases and infections in the urinary, vaginal and gastrointestinal tracts, as well as in the skin, making it a suitable alternative to conventional antibiotics.
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Cellulosic sugars extracted from vineyard pruning waste (VPW) were used as a low-cost carbon source for biosurfactant production by Lactobacillus paracasei. The results obtained ...showed that when glucose from VPW was used, the biosurfactant was a glycolipopeptide, whereas when it was replaced by lactose the biosurfactant produced was a glycoprotein. Additionally, it was found that the extraction process, either with phosphate-buffer or phosphate-buffer saline, influenced the biosurfactant chemical structure and emulsion capacity. Overall, these results highlight the possibility of producing biosurfactants “à la carte” with the same strain but changing the carbon source, increasing its potential in different industrial applications.
The conversion of β-carotene into xanthophylls is a subject of great scientific and industrial interest. We cloned the
crtS gene involved in astaxanthin biosynthesis from two astaxanthin producing ...strains of
Xanthophyllomyces dendrorhous: VKPM Y2410, an astaxanthin overproducing strain, and the wild type ATCC 24203. In both cases, the ORF has a length of 3166
bp, including 17 introns, and codes for a protein of 62.6
kDa with similarity to cytochrome-P450 hydroxylases.
crtS gene sequences from strains VKPM Y2410, ATCC 24203, ATCC 96594, and ATCC 96815 show several nucleotide changes, but none of them causes any amino acid substitution, except a G
2268 insertion in the 13th exon of ATCC 96815 which causes a change in the reading frame. A G
1470
→
A change in the 5′ splicing region of intron 8 was also found in ATCC 96815. Both point mutations explain astaxanthin idiotrophy and β-carotene accumulation in ATCC 96815. Mutants accumulating precursors of the astaxanthin biosynthetic pathway were selected from the parental strain VKPM Y2410 (red) showing different colors depending on the compound accumulated. Two of them were blocked in the biosynthesis of astaxanthin, M6 (orange; 1% astaxanthin, 71 times more β-carotene) and M7 (orange; 1% astaxanthin, 58 times more β-carotene, 135% canthaxanthin), whereas the rest produced lower levels of astaxanthin (5–66%) than the parental strain. When the
crtS gene was expressed in M7, canthaxanthin accumulation disappeared and astaxanthin production was partially restored. Moreover, astaxanthin biosynthesis was restored when
X. dendrorhous ATCC 96815 was transformed with the
crtS gene. The
crtS gene was heterologously expressed in
Mucor circinelloides conferring to this fungus an improved capacity to synthesize β-cryptoxanthin and zeaxanthin, two hydroxylated compounds from β-carotene. These results show that the
crtS gene is involved in the conversion of β-carotene into xanthophylls, being potentially useful to engineer carotenoid pathways.
The basidiomycete Hypholoma sublateritium produces clavaric acid, an antitumor isoprenoid compound. Arthrospores of this fungus were transformed by Agrobacterium tumefaciens-mediated conjugation. ...Five plasmids carrying different regulatory sequences to drive expression of the hph (hygromycin phosphotransferase) gene were tested. The promoter used was critically important in order to express heterologous genes in H. sublateritium. Constructions carrying the Agaricus bisporus glyceraldehyde-3-phosphate dehydrogenase promoter (P gpd) showed a good transformation efficiency, whereas constructions with the gpd promoter from ascomycetes were ineffective. Transformant clones showed a random integration pattern of plasmid DNA. Most transformants showed a single integrated copy of the transforming plasmid, but about 1.5% showed double or multiple integrations. All the analyzed transformants were mitotically stable and maintained the integrated exogenous DNA in the absence of antibiotic. The green fluorescent protein gene was expressed from the A. bisporus gpd promoter, as shown by RT-PCR studies, but no significant fluorescence was observed. Transformation of H. sublateritium opens the way for the genetic manipulation of clavaric acid biosynthesis in this fungus.
The capability of a cell bound biosurfactant produced by Lactobacillus pentosus, to accelerate the bioremediation of a hydrocarbon-contaminated soil, was compared with a synthetic anionic surfactant ...(sodium dodecyl sulphate SDS-). The biosurfactant produced by the bacteria was analyzed by Fourier transform infrared spectroscopy (FTIR) that clearly indicates the presence of OH and NH groups, C=O stretching of carbonyl groups and NH nebding (peptide linkage), as well as CH2–CH3 and C–O stretching, with similar FTIR spectra than other biosurfactants obtained from lactic acid bacteria. After the characterization of biosurfactant by FTIR, soil contaminated with 7,000 mg Kg−1 of octane was treated with biosurfactant from L. pentosus or SDS. Treatment of soil for 15 days with the biosurfactant produced by L. pentosus led to a 65.1% reduction in the hydrocarbon concentration, whereas SDS reduced the octane concentration to 37.2% compared with a 2.2% reduction in the soil contaminated with octane in absence of biosurfactant used as control. Besides, after 30 days of incubation soil with SDS or biosurfactant gave percentages of bioremediation around 90% in both cases. Thus, it can be concluded that biosurfactant produced by L. pentosus accelerates the bioremediation of octane-contaminated soil by improving the solubilisation of octane in the water phase of soil, achieving even better results than those reached with SDS after 15-day treatment.
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