Properties of crude laccase from Trametes versicolor produced by solid-substrate fermentation

A low-cost process for the production of laccases is necessary for a sustainable enzymatic wastewater treatment. Therefore, it is necessary to establish an easy and low-cost procedure for the production of laccase. In the present study the properties of crude laccase from Trametes versicolor produced by solid-substrate fermentation is investigated. The application of the enzyme for dye decolorization is also studied. Crude laccase from the studied culture established maximal activity at 45ºC. The enzyme retained over 90% of its activity in the temperature range 40- 47ºC and pH 4.5. The kinetic constants of the crude enzyme was also determined. In the presence of KCl, NaCl, CaCl2, MnSO4 and MgSO4, laccase demonstra- ted high stability—over 50% of its initial activity was still retained after 4-month incubation. Complete loss of enzymatic activity was observed in the presence of CuCl2, FeCl2, FeCl3 and NaN3 after 30 min of incubation. 100% decolorization by investigated crude laccase was completed in the case of Indigo Carmine for 4 h, Remazol Brilliant Blue R—for 6 h, Orange II— for 48 h and Congo Red—for 13 d.

Biotechnological potential of agro-industrial wastes for protein enrichment by solid-state fermentation using Aspergillus niger

This study is to assess the biotechnological potential of agro-industrial wastes of pineapple(Ananas comosus),sweet potato(Ipomoea batatas)and watermelon(Citrullus lanatus)for protein enrichment by solid-state fermentation using Aspergillus niger.Spore suspensions of A.niger were prepared with potato dextrose broth that had been supplemented with sodium chloride,ammonium nitrate and thiamine,and adjusted to pH of 5.Initial protein contents of sterile and non-sterile wastes of the pineapple,sweet potato,and watermelon were determined by the Kjeldahl method.The remaining sterile and non-sterile wastes was inoculated with spore suspensions of A.niger and incubated at temperature of 24℃ under conditions of solid-state fermentation for 14 days.Protein contents of the inoculated sterile and non-sterile wastes were determined after 7 and 14 days.The sterile wastes of pineapple,sweet potato and watermelon recorded initial percentage protein contents of 4.37,4.39,and 10.89,respectively,whereas their corresponding non-sterile wastes recorded initial percentage protein contents of 3.76,4.00,and 10.16,respectively.The results further show that percentage increase in protein content of sterile wastes after 14 days of fermentation were pineapple,35.01%;sweet potato,27.60%;and watermelon,64.40%.Percentage increase in protein content of non-sterile wastes after 14 days of fermentation were pineapple,72.34%;sweet potato,85.25%;and watermelon,80.51%.These findings affirm the biotechnological potential of pineapple,sweet potato and watermelon wastes and the importance of fungi as agents for protein enrichment of agro-industrial wastes.

Protein enrichment of cassava pulp by solid-state fermentation using Aspergillus niger

This study aimed to assess protein enrichment of sterile and non-sterile cassava pulp using four strains of Aspergillus niger-AN1,AN2,AN3,AN4.First,studies were conducted to evaluate nutritional requirements of A.niger strains and their suitability for protein enrichment of cassava pulp.Second,sterile and non-sterile cassava pulps were inoculated with spores of A.niger strains and incubated under conditions of solid-state fermentation for 8 days using standard methods.Protein contents of sterile and non-sterile cassava pulps were determined by the Kjeldahl method.Initial nutritional requirements studies showed that A.niger strains grew at rates between 2.0 cm and 8.5 cm over 10 days on potato dextrose agar medium of different pH.The dry weight of mycelia of A.niger strains varied in liquid media separately supplemented with different concentrations of thiamine,ammonium nitrate and sodium chloride.A.niger strains also showed different levels of sporulation when cultured in growth media supplemented with different concentrations of sodium chloride.Increases in protein contents of sterile cassava pulp by AN1,AN2,AN3 and AN4 were 15.65%,22.61%,18.30%and 19.13%,respectively.On non-sterile cassava pulp,the increases in protein content by AN1,AN2,AN3 and AN4 were 15.40%,21.54%,10.80%and 3.85%,respectively.A.niger strain AN2 was the most suitable strain for the enrichment of protein content of cassava because it sparsely produced spores,it had the highest mycelial growth and resulted in the greatest increase in protein content of both sterile and non-sterile cassava pulp.