Trametes hirsuta and a purified laccase from this organism were able to degrade triarylmethane, indigoid, azo, and anthraquinonic dyes. Initial decolorization velocities depended on the substituents on the phenolic rings of the dyes. Immobilization of the T. hirsuta laccase on alumina enhanced the thermal stabilities of the enzyme and its tolerance against some enzyme inhibitors, such as halides, copper chelators, and dyeing additives. The laccase lost 50% of its activity at 50 mM NaCl while the 50% inhibitory concentration (IC(50)) of the immobilized enzyme was 85 mM. Treatment of dyes with the immobilized laccase reduced their toxicities (based on the oxygen consumption rate of Pseudomonas putida) by up to 80% (anthraquinonic dyes). Textile effluents decolorized with T. hirsuta or the laccase were used for dyeing. Metabolites and/or enzyme protein strongly interacted with the dyeing process indicated by lower staining levels (K/S) values than obtained with a blank using water. However, when the effluents were decolorized with immobilized laccase, they could be used for dyeing and acceptable color differences (DeltaE*) below 1.1 were measured for most dyes.

https://repositorium.sdum.uminho.pt/bitstream/1822/2402/1/28.pdf

Decolorization and detoxification of textile dyes with a laccase from Trametes hirsuta.

Starting with a brief history of solid-state fermentation (SSF), major aspects of SSF are reviewed, which include factors affecting SSF, biomass, fermentors, modeling, industrial microbial enzymes, organic acids, secondary metabolites, and bioremediation. Physico-chemical and environmental factors such as inoculum type, moisture and water activity, pH, temperature, substrate, particle size, aeration and agitation, nutritional factors, and oxygen and carbon dioxide affecting SSF are reviewed. The advantages of SSF over Submerged Fermentation (SmF) are indicated, and the different types of fermentors used in SSF described. The economic feasibilities of adopting SSF technology in the commercial production of industrial enzymes such as amylases, cellulases, xylanase, proteases, phytases, lipases, etc., organic acids such as citric acid and lactic acid, and secondary metabolites such as gibberellic acid, ergot alkaloids, and antibiotics such as penicillin, cyclosporin, cephamycin and tetracyclines are highlighted. The relevance of applying SSF technology in the production of mycotoxins, biofuels, and biocontrol agents is discussed, and the need for adopting SSF technology in bioremediation of toxic compounds, biological detoxication of agro-industrial residues, and biotransformation of agro-products and residues is emphasized.

Solid-State Fermentation Systems—An Overview

Recent process developments in solid-state fermentation

Lignocelluloses are the building blocks of allplants and are ubiquitous to most regions ofour planet. Their chemical properties make it asubstrate of enormous biotechnological value.The basic chemistry of cellulose,hemicellulose, and lignin has a profound effecton lignocellulose tertiary architecture. Theseintricate associations constitute physical andchemical barriers to lignocellulose utilizationand biodegradation in natural and man-madeenvironments. Overcoming these barriers is thekey to unlocking the commercial potential oflignocellulose. Understanding lignocellulosedegradation under natural conditions forms thebasis of any lignocellulose-based application.A variety of microorganisms and mechanisms areinvolved in the complete biodegradation oflignocellulose in natural environments rangingfrom soil and rumen ecosystems to the termitehindgut. The primary objective oflignocellulose pretreatment by the variousindustries is to access the potential of thecellulose and hemicellulose encrusted by ligninwithin the lignocellulose matrix. Currentworking technologies based on the principles ofsolid-state fermentation (SSF) are brieflyreviewed. The use of unsterile lignocellulosicsfor bioremediation purposes holds promise forcost-effective environmental clean-upendeavors. Novel lignocellulose-basedapplications have found functionality intextile, biological control, and medicalresearch fields and might be exploited there inthe near future. Ultimately, lignocellulosewill probably accompany man to his voyages intospace for interest in this field isintensifying. Therefore, proper management oflignocellulose biodegradation and utilizationcan serve to improve the quality of theenvironment, further man's understanding of theuniverse, and ultimately change local economiesand communities.

/pdf/lignocellulose-biodegradation-fundamentals-and-applications-29s7g4vla2.pdf

B.K. Lonsane

Papers

Engineering aspects of solid state fermentation