Current developments in solid-state fermentation

• Solid-state fermentation (SSF) is a three-phase heterogeneous process.
• SSF is a promising green ‘technology’ for bioprocesses development.
• Agro-industrial residues offer best potential as substrate in SSF.
• We review the current state-of-art scenario and perspectives of SSF.

Solid-state fermentation (SSF) is a three-phase heterogeneous process, comprising solid, liquid and gaseous phases, which offers potential benefits for the microbial cultivation for bioprocesses and products development. Over the last two decades, SSF has gained significant attention for the development of industrial bioprocesses, particularly due to lower energy requirement associated with higher product yields and less wastewater production with lesser risk of bacterial contamination. In addition, it is eco-friendly, as mostly utilizes solid agro-industrial wastes (resides) as the substrate (source of carbon). This article aims to present and analyze the current development on SSF taken place mainly during the last five years, linking the developments with earlier two papers published in this journal in 2003 (Pandey, 2003 [1]) and in 2009 (Singhania et al., 2009 [2]). The article reviews the current state-of-art scenario and perspectives on the development of bioprocesses and products in SSF and also discusses microbes employed in these processes, the types of bioreactors used for these and also presents the modeling and kinetics aspects.