Acidogenic mixed consortium isolated from soil of agricultural field: acid production behaviour and growth kinetics under the influence of pretreatment hydrolysate of rice straw (RS)

ABSTRACT

The present study was conducted to assess the possibilities of biofuel production through volatile fatty acid (VFA) platform using mixed consortia isolated from a natural source (soil of rice cultivation field). The acid production potential of the isolated acidogenic mixed consortium UACJUChE1, using pretreatment hydrolysate of rice straw as the carbohydrate source, was assessed. Growth kinetic parameters i.e. maximum specific growth rate (μ_max) and substrate saturation constant (K_S) of UACJUChE1 have been determined separately for both glucose and hydrolysate in the Reinforced Clostridial Medium (RCM). A summative type growth model has been observed to be valid when the combination of glucose and RS-hydrolysate (RSH) is used as the carbon sources. The summative model has been validated by successful comparison of model predictions with the experimental data. The presence of VFAs in the culture broth of the consortium grown on glucose, RS-hydrolysate and their combination (Glc:RSH: 2:3; 1:4 (w/w)) has been established. The survival and growth of solventogenic Clostridium acetobutylicum in a growth medium amended with the effluent of these batch cultures of UACJUChE1 have been ascertained. This indicates a strong potential of UACJUChE1 in the hybridisation of the VFA platform and conventional sugar platform for the generation of butanol from RS.

GRAPHICAL ABSTRACT

KEYWORDS:

• Undefined acidogenic consortium
• rice straw
• pretreatment hydrolysate
• summative growth
• volatile fatty acid platform

Acknowledgements

The corresponding author sincerely acknowledges DST, India for sanctioning the financial support necessary for this research study under INNO-INDIGO Research project CONVER-B (Sanction Ref. DST/IMRCD/INNO-INDIGO/CONVER-B/2017(G) DATED January 29, 2018 and DST/IMRCD/INNO-INDIGO/CONVER-B/2017(C) DATED April 11, 2018). The cooperation rendered by the University of Eastern Finland regarding the NMR analysis of RS and RSH is also being acknowledged gratefully.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The corresponding author sincerely acknowledges DST, India for sanctioning the financial support necessary for this research study under INNO-INDIGO Research project CONVER-B (Sanction Ref. DST/IMRCD/INNO-INDIGO/CONVER-B/2017(G) DATED January 29, 2018 and DST/IMRCD/INNO-INDIGO/CONVER-B/2017(C) DATED April 11, 2018).