In this work, erythromycin production by Saccharopolyspora erythraea NCIMB 12462 was investigated under solid state fermentation (SSF) using beet sugar root (BSR) and agro-industrial materials. Among them oat meal (OM) has given maximum yield. The combination of OM with BSR (3:3 g/flask) proved to be an efficient mixture for erythromycin production as they gave the highest erythromycin level (6531 μg/flask) when compared to BSR and peptone. Supplementation of BSR and OM mixtures with sugarcane bagasse (SCB) as inert support with different inoculum size and additional water enhanced erythromycin production with 3.1-fold higher production than BSR- OM medium. However, increasing SCB content more than 3g/flask always showed an inhibitory effect on erythromycin production. Box-Behnken response surface methodology was applied to further optimize SCB content, inoculum size and moisture level for erythromycin production. Statistical analysis of the results showed that the linear of the selected terms, their interactions and quadric terms of these three variables had significant effects. The moisture level was the key factor influencing erythromycin production, due to its largest F-value (48.01) and the lowest p-value (0.0002) among the three variables. The interactions between SCB content and moisture level had also the most significant effect (F-value = 32.51) on erythromycin production. The optimized medium produced 29884 ug/flask of erythromycin under SSF, which is 1.1% higher than the unoptimized medium.
Box-Behnken design, Erythromycin, Medium optimization, Solid state fermentation, Saccharopolyspora erythraea NCIMB 12462