Production and shelf life evaluation of storable myco-granules for multiple environmental applications

Abstract

The present work describes a novel attempt to produce myco-granules targeted for multiple industrial applications including dye and heavy metal sequestration and xylanase production. Three low cost, locally available substrates FS1 (rice flour), FS2 (maize flour) and FS3 (wheat flour) were characterized and used for producing three myco-granules MG1, MG2 and MG3, respectively. Spore load of freshly prepared myco-granules and after 6 months of storage at 30 °C was estimated. MG1 exhibited least decrease (32%) in number of spores as compared to MG2 (40%) and MG3 (87%). Shelf-life studies conducted for different myco-granules stored at 4 °C, 30 °C and ambient temperature conditions show unaltered biomass production for the initial three months which rules out the need for controlled temperature conditions during storage. When stored at 30 °C, MG1 could remove 83% Acid Navy Blue dye, 57% Cu(II), >68% Cr(VI) (initial concentration 200 mg L−1 for dye and 50 mg L−1 for respective metals) and was able to produce 70.8 U g−1 crude xylanase activity through solid state fermentation after one year. The myco-granule MG1 has the potential of remediating wide varieties of wastewater containing dye and heavy metals as well as producing industrially important enzymes. Further, its prolonged shelf life under non-refrigerated conditions has highlighted its superiority over conventional means.