Exponential Fed-Batch Cultures of Klebsiella pneumoniae under Anaerobiosis Using Raw Glycerol as a Substrate to Obtain Value-Added Bioproducts

Abstract

In this study, Klebsiella pneumoniae BLh-1 was grown under exponential fed-batch mode in cultures using raw glycerol from biodiesel synthesis under anaerobiosis to produce value-added products. Specific growth rates of 0.035, 0.07, and 0.105 h-1 were tested and 1,3-propanediol (1,3-PDO) and ethanol were produced in all cultures, whereas the formation of 2,3-butanediol was not observed. The highest concentrations of 1,3-PDO (38.5 g L-1) and ethanol (13.2 g L-1) were achieved under the specific growth rate of 0.105 h-1. Acetic and lactic acids were also produced at high concentrations (17.3 and 7.8 g L-1 , respectively) under these conditions. The yields of 1,3-PDO and ethanol increased over time, reaching final values of 0.56 and 0.19 g g-1 , respectively. Overall productivities were 1.43 g L-1 h-1 for 1,3-PDO and 0.49 g L-1 h-1 for ethanol. Compared to batch results, fed-batch operation favored K. pneumoniae metabolism towards the production of 1,3-PDO and ethanol, being an interesting process to add value to the ever-growing availability of raw glycerol from biodiesel industry.

Relationship between feeding strategies and nitrogen sources in platform chemical bio-based 2,3-butanediol production in fed-batch fermentation

“…titer and yield (Table 2). Similar statistical results were reported by Morcelli et al 29 The highest 2,3-BDO production was observed at μ set = 0.17 h −1 , about 1.8-fold more elevated than the production in intermittent feeding. In turn, the Y P/S reached an average of 0.38 g g −1 for the assays at μ set < 0.24 h −1 against 0.32 g g −1 for μ set = 0.24 h −1 .…”

“…An increase in 2,3-BDO yield from 81% using glucose feeding without a nitrogen source to 93% using glucose feeding supplemented with urea at 10% of its concentration in the batch-phase was verified. In contrast, Morcelli et al 29 reported a nearly 60% reduction in 1,3-PDO yield when replacing the crude glycerol feeding with a complex culture medium containing crude glycerol and other nutrients in anaerobic fed-batch fermentation at exponential feeding. The lower 1,3-PDO production was accompanied by an improvement in cell biomass formation, indicating a possible shift in microbial metabolism towards cell plasticity in complex nutritional media.…”

“…Other studies have also reported substrate accumulation in 2,3-BDO production in fed-batch fermentation at exponential feeding because of the differences between μ set and μ real . 1,29 Incomplete glucose metabolism resulted in a low microbial activity ( μ real < μ set ), whose cell plasticity was already limited by the low initial NH 4 Cl amount of only 1.79 g L −1 used in this study. This concentration was set based on the initial glucose of 10 g L −1 and the initial C/N ratio of 8.5 g g −1 .…”

Biosynthesis of 1,3‐propanodiol and 2,3‐butanodiol from residual glycerol in continuous cell‐immobilized Klebsiella pneumoniae bioreactors

“…5 Several bioprocess technologies are being proposed based on the availability of glycerol and its potential to be used as microbial substrate (carbon source) to produce a wide range of chemicals by microorganisms. [6][7][8][9][10] Among these high added-value bioproducts obtained from glycerol are 1,3-propanediol (1,3-PD) and 2,3-butanediol (2,3-BD), which are widely used in the polymer industry. [10][11][12][13] The biotechnological production of these chemicals has been of great interest to researchers as an alternative to chemical synthesis.…”

Klebsiella pneumoniae – a useful pathogenic strain for biotechnological purposes: 1,3-propanediol biosynthesis

“…The biotechnological production of PDO is extensively studied by multiple research groups because of the major development of market demands worldwide for PDO [20][21][22]. PDO plays an important role in the synthesis of biodegradable plastics, namely for the polytrimethyleneterephtalalte (PTT) production [18,23].…”