Butyric acid fermentation from pretreated and hydrolysed wheat straw by an adapted Clostridium tyrobutyricum strain

• Published in: Microbial biotechnology 2015-09, Vol.8 (5), p.874-882
• Main Authors: Baroi, G. N., Baumann, I., Westermann, P., Gavala, H. N.
• Format: Article
• Language: English
• Subjects: Adaptation, Biological; Butyric Acid - metabolism; Clostridium tyrobutyricum; Clostridium tyrobutyricum - growth & development; Clostridium tyrobutyricum - metabolism; Fermentation; Plant Stems - metabolism; Triticum - metabolism; Triticum aestivum
• ISSN: 1751-7915; 1751-7915
• DOI: 10.1111/1751-7915.12304

Summary Butyric acid is a valuable building‐block for the production of chemicals and materials and nowadays it is produced exclusively from petroleum. The aim of this study was to develop a suitable and robust strain of Clostridium tyrobutyricum that produces butyric acid at a high yield and selectivity from lignocellulosic biomasses. Pretreated (by wet explosion) and enzymatically hydrolysed wheat straw (PHWS), rich in C6 and C5 sugars (71.6 and 55.4 g l−1 of glucose and xylose respectively), was used as substrate. After one year of serial selections, an adapted strain of C. tyrobutyricum was developed. The adapted strain was able to grow in 80% (v v−1) PHWS without addition of yeast extract compared with an initial tolerance to less than 10% PHWS and was able to ferment both glucose and xylose. It is noticeable that the adapted C. tyrobutyricum strain was characterized by a high yield and selectivity to butyric acid. Specifically, the butyric acid yield at 60–80% PHWS lie between 0.37 and 0.46 g g−1 of sugar, while the selectivity for butyric acid was as high as 0.9–1.0 g g−1 of acid. Moreover, the strain exhibited a robust response in regards to growth and product profile at pH 6 and 7. Successive adaptation of a Clostridium tyrobutyricum strain to Pretreated and enzymatically Hydrolysed Wheat Straw (PHWS) resulted in an adapted strain able to grow in 80% (v v‐1) PHWS. The adapted C. tyrobutyricum strain was characterised by a high yield and selectivity to butyric acid (0.37‐0.46 g g‐1 sugars and 0.9‐1.0 g g‐1 acids, respectively) and it exhibited a robust response in regards to growth and products profile at pH 6 and 7.