High level of 1,3‐propanediol production from crude glycerol by Clostridium strain BOH3: critical roles of inoculum and substrate concentration

Abstract

BACKGROUND1,3‐Propanediol (PDO) is a raw material/specialty chemical/additive in several industrial applications. A new wild‐type Clostridium strain BOH3 can utilize crude glycerol (CG) and produce PDO. This investigation reveals its potential for PDO production from CG.RESULTSInitially, inoculum of strain BOH3 was cultured from reinforced clostridial medium (RCM) with glucose (medium‐A), and modified‐RCM with glycerol (medium‐B). While fermenting 20 g/L glycerol, the cells cultivated from medium‐A produced 5.75 g/L PDO (as major product) with 3.10 g/L butanol (byproduct), whereas the cells cultivated from medium‐B produced 11.01 g/L PDO with 2.50 g/L butyric, and 1.01 g/L acetic acids, and no butanol was produced. To enhance PDO production from the batch‐process, various parameters including pure glycerol/CG concentration (80 g/L), inoculum age (15 h) and size (12.50%v/v) of cells from medium‐B, initial medium‐pH (pH 6.4), and incubation temperature (39 °C) were studied; the optimal values obtained are given in their respective parenthesis. Under optimal conditions, PDO production was 42.58–47.15 g/L (0.65–0.79 mol‐PDO/mol‐glycerol) from CG‐based rich/mineral media. Furthermore, fed‐batch fermentation with 50–80 g/L initial CG‐concentration was tested to enhance the PDO production. Among these, 60 g/L initial CG‐concentration assisted strain BOH3 in utilizing a high level of CG (~174 g/L); it supported a higher‐titer of PDO production (103.55–116.45 g/L), with the highest yield (0.72–0.81 mol‐PDO/mol‐glycerol) ever reported.CONCLUSIONClostridium strain BOH3 shows the potential to support a high titer (>116 g/L) with the highest yield (>0.80 mol/mol) of PDO production from CG (a waste). It can be considered for industrial‐scale PDO production.This article is protected by copyright. All rights reserved.