Overproduction of Laccase and Pectinase by Microbial Associations in Solid Substrate Fermentation

Mathematical modeling for operative improvement of the decoloration of Acid Red 27 by a novel microbial consortium of Trametes versicolor and Pseudomonas putida: A multivariate sensitivity analysis

In this work, it is presented a first approach of a mathematical and kinetic analysis for improving the decoloration and further degradation process of an azo dye named acid red 27 (AR27), by means of a novel microbial consortium formed by the fungus Trametes versicolor and the bacterium Pseudomonas putida. A multivariate analysis was carried out by simulating scenarios with different operating conditions and developing a specific mathematical model based on kinetic equations describing all stages of the biological process, from microbial growth and substrate consuming to decoloration and degradation of intermediate compounds. Additionally, a sensitivity analysis was performed by using a factorial design and the Response Surface Method (RSM), for determining individual and interactive effects of variables like, initial glucose concentration, initial dye concentration and the moment in time for bacterial inoculation, on response variables assessed in terms of the minimum time for: full decoloration of AR27 (R1 = 2.375 days); maximum production of aromatic metabolites (R2 = 1.575 days); and full depletion of aromatic metabolites (R3 = 12.9 days). Using RSM the following conditions improved the biological process, being: an initial glucose concentration of 20 g l-1, an initial AR27 concentration of 0.2 g l-1 and an inoculation moment in time of P. putida at day 1. The mathematical model is a feasible tool for describing AR27 decoloration and its further degradation by the microbial consortium of T. versicolor and P. putida, this model will also work as a mathematical basis for designing novel bio-reaction systems than can operate with the same principle of the described consortium.

Enhancing the degradation of Aflatoxin B1 by co-cultivation of two fungi strains with the improved production of detoxifying enzymes

After the co-culture of Aspergillus niger and Pleurotus ostreatus, the obtained extracellular crude enzymes solution was employed to aflatoxin B₁ (AFB₁) degradation. The maximum AFB₁ degradation with co-culture reached 93.4%, which increased by 65.9% and 37.6%, respectively, compared with those of the mono-culture of Pleurotus ostreatus and Aspergillus niger. The molecular weight of the key detoxifying enzymes isolated by ultrafiltration was 58 and 63 kDa by SDS-PAGE analysis. The purified detoxifying enzymes had a high detoxification effect on AFB₁ with the degradation rate of 94.7%. It was found that the co-culture of Pleurotus ostreatus and Aspergillus niger promoted the production of 58 and 63 kDa detoxifying enzymes to enhance the AFB₁ degradation. The chemical structure of major degradation products of AFB₁ by the mixed cultures were preliminarily identified by LC-Triple TOF MS. Two pathways of AFB₁ degradation were inferred with the high potential of fungal co-cultivations for AFB₁ detoxification applications.

Co-Cultivation of Two Bacillus Strains for Improved Cell Growth and Enzyme Production to Enhance the Degradation of Aflatoxin B1

Bacillus sp. H16v8 and Bacillus sp. HGD9229 were identified as Aflatoxin B₁ (AFB₁) degrader in nutrient broth after a 12 h incubation at 37 °C. The degradation efficiency of the two-strain supernatant on 100 μg/L AFB₁ was higher than the bacterial cells and cell lysate. Moreover, degradations of AFB₁ were strongly affected by the metal ions in which Cu²⁺ stimulated the degradation and Zn²⁺ inhibited the degradation. The extracellular detoxifying enzymes produced by co-cultivation of two strains were isolated and purified by ultrafiltration. The molecular weight range of the detoxifying enzymes was 20-25 kDa by SDS-PAGE. The co-culture of two strains improved the total cell growth with the enhancement of the total protein content and detoxifying enzyme production. The degradation efficiency of the supernatant from mixed cultures increased by 87.7% and 55.3% compared to Bacillus sp. H16v8 and HGD9229, individually. Moreover, after the degradation of AFB₁, the four products of the lower toxicity were identified by LC-Triple TOF-MS with the two proposed hypothetical degradation pathways.

Trametes versicolor in lignocellulose-based bioeconomy: State of the art, challenges and opportunities

Although Trametes versicolor is one of the most investigated white-rot fungi, the industrial application of this fungus and its metabolites is still far from reaching its full potential. This review aims to highlight the opportunities and challenges for the industrial use of T. versicolor according to the principles of circular bioeconomy. The use of this fungus can contribute significantly to the success of efforts to valorize lignocellulosic waste biomass and industrial lignocellulosic byproducts. Various techniques of T. versicolor cultivation for enzyme production, food and feed production, wastewater treatment, and biofuel production are listed and critically evaluated, highlighting bottlenecks and future perspectives. Applications of T. versicolor crude laccase extracts in wastewater treatment, removal of lignin from lignocellulose, and in various biotransformations are analyzed separately.

Coculture, An Efficient Biotechnology for Mining the Biosynthesis Potential of Macrofungi via Interspecies Interactions

Macrofungi, which are also known as mushrooms, can produce various bioactive constituents and have become promising resources as lead drugs and foods rich in nutritional value. However, the production of these bioactive constituents under standard laboratory conditions is inefficiency due to the silent expression of their relevant genes. Coculture, as an important activation strategy that simulates the natural living conditions of macrofungi, can activate silent genes or clusters through interspecific interactions. Coculturing not only can trigger the biosynthesis of diverse secondary metabolites and enzymes of macrofungi, but is also useful for uncovering the mechanisms of fungal interspecific interactions and novel gene functions. In this paper, coculturing among macrofungi or between macrofungi and other microorganisms, the triggering and upregulation of secondary metabolites and enzymes, the potential medicinal applications, and the fungal-fungal interaction mechanisms are reviewed. Finally, future challenges and perspectives in further advancing coculture systems are discussed.

Enhancing laccase production by white-rot fungus trametes hirsuta SSM-3 in co-culture with yeast sporidiobolus pararoseus SSM-8

Due to wide application of laccase, many researchers have shown great interest in over production of white-rot fungi laccase by co-culture. In this study, a white-rot fungus Trametes hirsuta SSM-3, and a yeast Sporidiobolus pararoseus SSM-8 were isolated and identified from Mulberry fruit. The capacity of S. pararoseus to enhance laccase production was remarkable in T. hirsuta, yielding 31777 ± 742 U/L, about 9.9 times higher than the result from the monoculture. The stimulatory factor in the S. pararoseus cells might be temperature-sensitive. The laccase production was enhanced by oil-extract of S. pararoseus and β-carotene induction. The amylase activity was decreased rapidly when strain S. pararoseus SSM-8 was inoculated. The glucose deprivation was occurred both in the mono-culture and co-culture process, and S. pararoseus propagated slowly in co-culture all the time. Native-PAGE revealed an increase of laccase-1(lac-1) level and a laccase-3 (lac-3) in the co-culture. Therefore, it was concluded that competition for resources between the co-cultured microbes leaded to amylase decreasing and the enhanced production of laccase. This conclusion was helpful for the development of laccase fermentation industry because it provided an effective, simple and economic method to improve the yield of laccase.