Efficient utilization of cassava pulp for succinate production by metabolically engineered Escherichia coli KJ122

Abstract

A metabolically engineered Escherichia coli KJ122 was efficiently utilized for succinate production from cassava pulp during batch separate hydrolysis and fermentation (SHF) under simple anaerobic conditions. Succinate concentration of 41.46 ± 0.05 g/L with yield and productivity of 82.33 ± 0.14 g/100 g dry pulp and 0.84 ± 0.02 g/L/h was obtained. In batch simultaneous saccharification and fermentation (SSF), hydrolysis of 12 % (w/v) cassava pulp with an enzyme loading of 2 % AMG + 3 % Cel (v/w) at pH 6.5 was optimized at 39 °C. Succinate concentration of 80.86 ± 0.49 g/L with a yield of 70.34 ± 0.37 g/100 g dry pulp and a productivity of 0.84 ± 0.01 g/L/h was attained using E. coli KJ122. Fed-batch SSF significantly enhanced succinate concentration to 98.63 ± 0.12 g/L at yield and productivity of 71.64 ± 0.97 g/100 g dry pulp and 1.03 ± 0.01 g/L/h. This result indicated an efficient and economical succinate production from cassava pulp using SHF and SSF by the use of E. coli KJ122.

High production yield and specific productivity of succinate from cassava starch by metabolically-engineeredEscherichia coliKJ122

“…Chen and colleagues revealed that the highest specific productivity of 171 mg g −1 CDW h −1 was achieved when glucose was used as carbon source by E. coli NZN111. Sawisit and colleagues also found that the specific productivity of succinate of 235 mg g −1 CDW h −1 was reached from batch fermentation of cassava pulp by the strain KJ122. The results suggested that E. coli KJ122 exhibited high efficiency in the specific productivity of succinate from glucose‐based and even cassava‐derived substrates during batch fermentation compared with previously reported work.…”

“…In contrast, while an enzyme loading higher or lower than 400 U AMG g −1 powder had a negative effect on 2,3‐butanediol production by the strain in the SSF process. Sawisit and colleagues also found that the highest efficacy of cassava pulp hydrolysis with cellulase complex loading at 3% (v w −1 ) on dry pulp combined with 2% (v w −1 on dry pulp) AMG was achieved during succinate production by the strain KJ122 in SSF. No further improvement in sugars and succinate production from cassava pulp was observed when more concentrations of cellulase complex were provided.…”

“…Our result was similar to other published works. Sawisit and colleagues also performed succinate production from cassava pulp using the SSF process. They revealed that no significant differences in succinate titers and yields were observed when the fermentation was performed at temperatures ranging from 37 to 41 °C.…”

“…succiniciproducens from 0.60 to 0.88 g g −1 glucose during fed‐batch fermentation in comparison with the batch process performed with similar glucose concentrations. Sawisit and colleagues also mentioned that higher succinate concentration and average productivity from cassava pulp were observed during fed‐batch SSF compared with those found in batch experiments by the E. coli KJ122. Therefore, the results confirmed that succinate concentration, yield, and productivity could be efficiently improved by the fed‐batch process compared with the batch SSF process.…”

“…However, the cost of succinate produced by chemical synthesis is $5.9–8.8 kg −1 . In addition, Sawisit and colleagues recently proposed that the price of succinate produced by microbial fermentation from cassava pulp was about $5.21–5.45 kg −1 succinate. It is likely that the utilization of cassava starch may make the microbial succinate production by E. coli KJ122 more economically competitive.…”