Sugarcane bagasse (SB) is a promising source of appreciable quantities of fermentable sugars. However, the presence of lignin hinders utilization of these carbohydrates and hence pretreatment to remove lignin is necessarily carried out. Here, a biological pretreatment method was synchronized with the production of a thermostable cellulase using SB as a raw material. Initially, bagasse was fermented by a laccase producing fungus, Trametes pubescens MB 89 under solid state fermentation (SSF) and a titer of 1758 IU mL −1 of laccase was obtained. Investigations of nine factors affecting laccase production through Plackett Burman design improved the titers to 6539 IU mL −1 . Five factors (incubation period, concentration of CuSO 4 , temperature, moisture content, and particle size) were found significant which were optimized through Central Composite design leading to an improvement in the titers by ~5 folds (8841 IU mL −1 ). Biologically pretreated SB was fermented by a thermophilic bacterium, Neobacillus sedimentimangrovi UE25, that yielded 8.64 IU mL −1 of cellulase. Delignification and cellulose utilization were affirmed by structural analysis through FTIR and SEM. The synchronized process yielded higher titers of laccase and cellulase under SSF of SB with the minimum use of corrosive chemicals.
Fungi, being an integral constituent of this earth, cause contamination in many food stuffs including dried fruits and nuts. This fungal contamination not only leads to spoilage of these nutritive substances but also responsible for mycoses and mycotoxicoses among consumers especially immune compromised individuals. Keeping in view this aspect, this study was designed to investigate the fungal contamination in dried fruits and nuts sold in local markets of Karachi city. For this purpose, a total of eighty-four samples of dried fruits and nuts were collected from different local vendors in Karachi. These samples were crushed and screened for the presence of fungal contamination by streaking on Sabouraud`s dextrose agar. The fungal colonies appeared were identified by macroscopic and microscopic study. The isolated strains were further tested for their susceptibility to antifungal agents by using disc diffusion method. The aflatoxigenic strains among isolated Aspergillus species were also detected by using cultural methods (Ammonium hydroxide technique and Ultra Violet Photography technique).The overall results exhibited presence of high fungal load in dried fruits and nuts particularly in raisins and apricots. The samples collected from local markets (Karachi) were found more contaminated as compared to those obtained from their sites of origin (Gilgit). Aspergillus niger was isolated as the most predominant species (25.8%) followed by A. flavus (19.35%) among all isolated fungal strains. Among all A. flavus strains, 18% were found aflatoxigenic as detected by cultural method. Furthermore, the isolated fungal strains exhibited 100% resistance against fluconazole, while high resistance against Amphotericin B was also recorded by many fungal strains. High burden of drug resistant and aflatoxigenic fungi in edible items such as dried fruits and nuts pose an upcoming threat for human population therefore needs prompt management.
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