Antifungal effect of triclosan on Aspergillus fumigatus: quorum quenching role as a single agent and synergy with liposomal amphotericin-B

The purpose of this research was to determine Aspergillus fumigatus conidial viability and its biofilm formation upon treatment with triclosan and amphotericin-B loaded liposomes. A. fumigatus was treated with the antimicrobials, triclosan and liposomal amphotericin-B (L-AMB), in single and combined supplementation. To quantify the cells’ viability upon treatments, resazurin-based viability assay was performed. Confocal laser scanning microscopy was done by applying FUN-1 stain to screen the role of the agents on extracellular polymeric substances. Total A. fumigatus biomass upon treatments was estimated by using crystal violet-based assay. To study the agents’ effect on the conidial viability, flow cytometry analysis was performed. Expression levels of A. fumigatus genes encoding cell wall proteins, α-(1,3)-glucans and galactosaminogalactan were analysed by real-time polymerase chain reaction assay. A synergistic interaction occurred between triclosan and L-AMB when they were added sequentially (triclosan + L-AMB) at their sub-minimum inhibitory concentrations, the triclosan and L-AMB MICs were dropped to 0.6 and 0.2 mg/L, respectively, from 2 to 1 mg/L. Besides, L-AMB and triclosan contributed to the down-regulation of α-(1,3)-glucan and galactosaminogalactan in A. fumigatus conidia and resulted in less conidia aggregation and mycelia adhesion to the biotic/abiotic surfaces; A. fumigatus conidia-became hydrophilic upon treatment, as a result of rodlet layer being masked by a hydrophilic layer or modified by the ionic strength of the rodlet layer. In A. fumigatus, the potential mechanisms of action for L-AMB might be through killing the cells and for triclosan through interrupting the cells’ development as a consequence of quorum quenching

Repeated batch for dye degradation in an airlift bioreactor by laccase entrapped in copper alginate

A repeated batch of synthetic dye decolorization was efficiently demonstrated in a 5 L airlift bioreactor. A laccase from Ganoderma sp. KU-Alk4, degrading commercial aromatic dyes was selected. The crude enzyme extract expressed laccase activity, and was immobilized under optimal conditions in copper-alginate beads, 3 IU/bead. The immobilized enzyme showed high efficiency in degrading various synthetic dyes under non-buffered conditions, in particular the indigoid dye Indigo Carmine. The immobilized laccase also showed marked increase in stability toward temperature and pH when compared with free enzyme preparation. Immobilization enhanced its temperature stability to maintain initial activity up to 55 °C, ten degrees higher than the free enzyme. The immobilized laccase was stable in the alkaline region up to pH 10.0. The dye decolorization system in 5 L airlift bioreactor was demonstrated with 25 mg/L Indigo Carmine dissolved in tap water and a total immobilized laccase activity of 6 × 104 IU. Airflow rate was the most important factor affecting the number of batch runs and the time for 100% dye degradation. An optimal airflow rate was of 4 L/min. Fourteen batch runs of complete dye degradation were successfully completed with only a single enzyme supplementation, and this could be a feasible system for operation in industry. Total dye degraded by this repeated process at 4 L/min airflow rate was 1.8 g. Isatin sulfonic acid was a metabolic product of Indigo Carmine degradation catalyzed by the immobilized laccase. This development of an effective repeatable bioprocess using enzymes for the treatment of dye-contaminated effluent has potential for implementation on an industrial scale

Auslander's Formula for contravariantly finite subcategories

A relative version of Auslander's formula with respect to a contravariantly finite subcategory will be given. Dual version will be treated. Several examples and applications will be provided. In particular, we show that under certain circumstances, if relative Auslander algebras of artin algebras $\Lambda$ and $\Lambda'$ are Morita equivalent, then $\Lambda$ and $\Lambda'$ are also Morita equivalent

Quorum quenchers affect the virulence regulation of non-mucoid, mucoid and heavily mucoid biofilms co-cultured on cell lines.

Biofilm formation conferring pathogenicity is a survival strategy for Pseudomonas aeruginosa. P. aeruginosa's virulence may differ due to differences in host-microbe interactions and the growth environment. The epithelial cell line within the respiratory system and the keratinocytes on the skin form the first physical barrier of defence. P. aeruginosa spp. biofilm formation and virulence factor secretion with and without quorum quenching (QQ) treatment was studied in co-culture using A549 and HaCaT cell lines; pyocyanin and rhamnolipid productions and elastolytic activity as virulence factors were quantified by independent assays. Biofilm formation was evaluated under dynamic conditions by quantifying total carbohydrates, alginate, proteins and eDNA. A sandwich ELISA was performed to study IL-8 secretion by the epithelial cells. The difference in gene expression of the quorum sensing (QS) and virulence factors between strains during individual and combination treatments was analysed by qPCR. Combination treatment by farnesol and tyrosol was more effective against P. aeruginosa biofilms when grown in co-cultures. The strain RBHi was found to be 3 to 4 times more virulent compared to PAO1 and NCTC 10,662, respectively, and combination treatment was more effective against RBHi strain when grown in co-culture with A549 cell line. The addition of quorum quenchers (QQs) individually and in combination reduced IL-8 secretion by A549 cells. Relative mRNA expression showed upregulation of the QS genes and virulence factors. Co-culture of P. aeruginosa and HaCaT cell line showed a general decrease in gene expression, especially in the case of P. aeruginosa RBHi when treated with farnesol and tyrosol combination.Key points• Differentiating the interactions of biofilm formed by different phenotypes of P. aeruginosa, NCTC 10,662 (non-mucoid), PAO1 (semi mucoid) and RBHi (heavily mucoid).• Biofilm formed by these P. aeruginosa strains on two commonly afflicted tissues represented by A549 (lung) and HaCaT (skin) cell lines.• Anti-biofilm/anti-virulence roles of quorum quenchers, tyrosol and farnesol in co-cultures. [Abstract copyright: © 2021. The Author(s).