Isolation of Fungi from a Textile Industry Effluent and the Screening of Their Potential to Degrade Industrial Dyes.

Six fungal strains were isolated from the textile industry effluent in which they naturally occur. Subsequently, the fungal strains were identified and characterized in order to establish their potential decolorizing effect on textile industry effluents. The strains of interest were selected based on their capacity to decolorize azo, indigo, and anthraquinone dyes. Three of the strains were identified as Emmia latemarginata (MAP03, MAP04, and MAP05) and the other three as Mucor circinelloides (MAP01, MAP02, and MAP06), while the efficiency of their decolorization of the dyes was determined on agar plate and in liquid fermentation. All the strains co-metabolized the dyes of interest, generating different levels of dye decolorization. Plate screening for lignin-degrading enzymes showed that the MAP03, MAP04, and MAP05 strains were positive for laccase and the MAP01, MAP02, and MAP06 strains for tyrosinase, while all strains were positive for peroxidase. Based on its decolorization capacity, the Emmia latemarginata (MAP03) strain was selected for the further characterization of its growth kinetics and ligninolytic enzyme production in submerged fermentation under both enzyme induction conditions, involving the addition of Acetyl yellow G (AYG) dye or wheat straw extract, and no-induction condition. The induction conditions promoted a clear inductive effect in all of the ligninolytic enzymes analyzed. The highest level of induced enzyme production was observed with the AYG dye fermentation, corresponding to versatile peroxidase (VP), manganese peroxidase (MnP), and lignin peroxidase (LiP). The present study can be considered the first analysis of the ligninolytic enzyme system of Emmia latemarginata in submerged fermentation under different conditions. Depending on the results of further research, the fungal strains analyzed in the present research may be candidates for further biotechnological research on the decontamination of industrial effluents.

The decolorization and degradation of azo dyes by two Stenotrophomonas strains isolated from textile effluent (Tepetitla, Mexico).

Stenotrophomonas' metabolic versatility plays important roles in the remediation of contaminated environment and plant growth promotion. We investigated two Stenotrophomonas strains isolated from textile polluted sewage for their ability to decolorize and degrade azo dyes. Two Stenotrophomonas strains (TepeL and TepeS) were isolated from textile effluents (Tepetitla, Mexico) using the selective agar Stenotrophomonas vancomycin, imipenem, amphotericin B agar (SVIA). Isolates' identity was determined by the sequencing of their partial 16S rRNA fragments. Their abilities to decolorize dyes were tested in a Luria broth supplemented with varying concentrations (50 mg/L-1 g/L) of textile dyes (acidic red, methyl orange, reactive green, acidic yellow, and reactive black). Fourier-transform infrared (FTIR) spectroscopy and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) metabolite analyses were used to determine the effect of the isolates' growth on the dyes (acidic red, methyl orange). We also identified the enzymes that may be involved in the degradation process. Phylogenetic analysis based on the 16S rDNA sequences showed that the isolates belong to the genus Stenotrophomonas. Stenotrophomonas sp. TepeL and TepeS respectively decolorize all the azo dyes at the tested concentration except at 1 g/L and degraded the azo dyes. The degradation resulted in the formation of N, N-dimethyl p-phenylenediamine, and sodium 4-amino-1-naphthalenesulfonate from methyl orange and acid red. TepeL and TepeS rapidly decolorized and degraded the azo dyes tested. This result showed that the two isolates have a good potential for the decontamination of textile effluents.

Pseudocrossidium replicatum (Taylor) R.H. Zander is a fully desiccation-tolerant moss that expresses an inducible molecular mechanism in response to severe abiotic stress.

KEY MESSAGE: The moss Pseudocrossidium replicatum is a desiccation-tolerant species that uses an inducible system to withstand severe abiotic stress in both protonemal and gametophore tissues. Desiccation tolerance (DT) is the ability of cells to recover from an air-dried state. Here, the moss Pseudocrossidium replicatum was identified as a fully desiccation-tolerant (FDT) species. Its gametophores rapidly lost more than 90% of their water content when exposed to a low-humidity atmosphere [23% relative humidity (RH)], but abscisic acid (ABA) pretreatment diminished the final water loss after equilibrium was reached. P. replicatum gametophores maintained good maximum photosystem II (PSII) efficiency (Fv/Fm) for up to two hours during slow dehydration; however, ABA pretreatment induced a faster decrease in the Fv/Fm. ABA also induced a faster recovery of the Fv/Fm after rehydration. Protein synthesis inhibitor treatment before dehydration hampered the recovery of the Fv/Fm when the gametophores were rehydrated after desiccation, suggesting the presence of an inducible protective mechanism that is activated in response to abiotic stress. This observation was also supported by accumulation of soluble sugars in gametophores exposed to ABA or NaCl. Exogenous ABA treatment delayed the germination of P. replicatum spores and induced morphological changes in protonemal cells that resembled brachycytes. Transcriptome analyses revealed the presence of an inducible molecular mechanism in P. replicatum protonemata that was activated in response to dehydration. This study is the first RNA-Seq study of the protonemal tissues of an FDT moss. Our results suggest that P. replicatum is an FDT moss equipped with an inducible molecular response that prepares this species for severe abiotic stress and that ABA plays an important role in this response.

Effect of textile dyes on activity and differential regulation of laccase genes from Pleurotus ostreatus grown in submerged fermentation.

This research was conducted to extend the knowledge on the differential regulation of laccase genes in response to dyes. In order to accomplish this, we analyzed both, the expression of five laccase genes by real time RT-qPCR, and also the laccase activity and isoforms patterns during the time-course of a Pleurotus ostreatus submerged fermentation supplemented with either acetyl yellow G (AYG) or remazol brilliant blue R (RBBR) dyes. For the purpose of obtaining a stable reference gene for optimal normalization of RT-quantitative PCR gene expression assays, we tested four candidate reference genes. As a result of this analysis, gpd was selected as reference index for data normalization. The addition of dyes had an induction effect on the enzymatic activity and also modified the zymogram profile. Fermentation with RBBR showed the highest laccase activity and number of isoforms along the course of the fermentation. Laccase gene expression profiles displayed up/down regulation along the fermentation time in four laccase genes (pox4, pox3, poxa1b and pox2), while pox1 was not expressed in either of the fermentation conditions. AYG addition caused the highest induction and repression levels for genes pox3 and poxa1b respectively. The expression level for all genes in the presence of RBBR were lower than in AYG, being in both conditions this response growth time dependent. These results show the influence of the nature of dyes on the induction level of laccase activity and on the differential regulation of the laccase genes expression in P. ostreatus.

A perspective on the use of Pleurotus for the development of convenient fungi-made oral subunit vaccines.

This review provides an outlook of the medical applications of immunomodulatory compounds taken from Pleurotus and proposes this fungus as a convenient host for the development of innovative vaccines. Although some fungal species, such as Saccharomyces and Pichia, occupy a relevant position in the biopharmaceutical field, these systems are essentially limited to the production of conventional expensive vaccines. Formulations made with minimally processed biomass constitute the ideal approach for developing low cost vaccines, which are urgently needed by low-income populations. The use of edible fungi has not been explored for the production and delivery of low cost vaccines, despite these organisms' attractive features. These include the fact that edible biomass can be produced at low costs in a short period of time, its high biosynthetic capacity, its production of immunomodulatory compounds, and the availability of genetic transformation methods. Perspectives associated to this biotechnological application are identified and discussed.

Influence of initial pH of the growing medium on the activity, production and genes expression profiles of laccase of Pleurotus ostreatus in submerged fermentation

Background: Enzymatic activity and laccase isoenzymes number of Pleurotus ostreatus grown in different pH values of the growing medium in submerged fermentation and incubated in buffer solutions of different initial pH values were determined. The expression profiles of five laccase genes (Lacc1, Lacc4, Lacc6, Lacc9 and Lacc10) in these cultures were also studied. Results: The highest laccases activity was obtained in cultures grown at initial pH of 4.5 and the lowest in cultures grown at initial pH of 8.5. Isoenzyme profiles were different in all the cases. Lacc1, Lacc4, Lacc6 and Lacc10 were expressed in all the cultures. Conclusions: The initial pH of the growing medium is an important factor for regulating the expression of laccase genes, having an effect on the activity and on the laccase isoenzymes number produced by P. ostreatus in SmF. This is the first report on the influence of different initial pH values of the growing medium on the laccases activity, laccase isoenzymes number and laccases expression profiles of P. ostreatus grown in submerged fermentation.

Ligninolytic activity patterns of Pleurotus ostreatus obtained by submerged fermentation in presence of 2,6-dimethoxyphenol and remazol brilliant blue R dye.

The degradation of 2,6-dimethoxyphenol (DMP) and decolorization of Remazol brilliant blue R dye (RBB), added to culture media of Pleurotus ostreatus developed in submerged fermentation, and the laccase, manganese peroxidase and veratryl alcohol oxidase activities produced in these systems were evaluated. Both compounds were removed from the culture medium mainly by enzymatic action. These compounds decreased the specific growth rate and the effect on the maximal biomass values was not important. The enzymatic activities were increased by DMP and/or RBB; however, the DMP showed a higher inducer effect on all enzymes than RBB. On the other hand, the RBB showed a larger inducer effect on manganese peroxidase activity than on the laccases and veratryl alcohol oxidase activities. These results show that DMP was a better inducer of ligninolytic enzymes than dye, and the process of dye decolorization and degradation of DMP requires the action of all enzymes of the ligninolytic complex.