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.

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.

Synthetic dyes are highly recalcitrant and are discharged in large volumes in industrial wastewater, which represents a serious environmental pollution problem. Biological methods for dye degradation are a potentially effective option for these synthetic products. In this study, a strain of Pleurotus ostreatus was used to evaluate the decolorization of the Remazol Brilliant Blue R (RBBR) dye added to the culture medium in the exponential growth phase of the fungus. The dye removal capacity of live and inactivated pellets by biosorption, as well as the enzymatic degradation of the dye using a cell-free culture broth considered an extracellular extract (EE), were also evaluated. The activity of laccase and dye-decolorizing peroxidase was determined in both the EE and the intrapellet extract (IPE); their values increased in the presence of dye in the culture medium. A decolorization of 98.5% and 98.0% was obtained in the culture broth and by the EE, respectively; biosorption of the dye by the inactivated pellets was 17 mg/g. The results suggest that the decolorization of the dye is primarily enzymatic, although there are also bioadsorption and bioaccumulation of the dye, which is then enzymatically degraded, and could be used as a carbon source.

Wild maize (teosinte) has been reported to be less susceptible to biotic and abiotic stresses than its modern relative, corn. The composition of the teosinte root microbiome may be linked to traits such as drought tolerance and pest resistance. Trichoderma spp. are ubiquitous saprotrophic fungi found in the plant rhizosphere, enhancing host plant growth and crop productivity while alleviating biotic and abiotic stresses. The present study identified ten Trichoderma fungal isolates associated with the rhizosphere microbiome of teosinte (Zea mays spp. mexicana) and performed in vitro screening to assess both their multi-trait plant growth-promoting activities and their biological control potential against the phytopathogens Aspergillus flavus and Fusarium verticillioides. Additionally, interaction tests were conducted to evaluate the phytostimulant effect of Trichoderma spp. on maize (Zea mays) seed germination. Taxonomic and phylogenetic analysis identified five different Trichoderma species: T. rifaii (TA and TH); T. azevedoi (TB and TI); T. afroharzianum (TE); T. hamatum (TF and TG); and Trichoderma sp. (aff. bannaense) (TC, TD, and TJ). Partial least squares discriminant analysis revealed the isolates TF, TG, and TJ to have the highest potential for use as biocontrol and biostimulant agents. The present study is the first to examine Trichoderma species associated with the teosinte microbiome, and the results suggest that Trichoderma isolates are a potential sustainable alternative for improving maize cultivation.