A simple novel approach for real-time monitoring of sodium gluconate production by on-line physiological parameters in batch fermentation by Aspergillus niger

•First-time established the approach for real-time monitoring SG fermentation.•Limiting factors during industrial SG production were found out and solved.•SG production rate improved 104.2% compared to the initial fermentation.•Overall yield was 16.0% higher than that in the initial fermentation.•Extremely low biomass (1.5 g L−1) was adopted for SG production.

In this paper, approach for real-time monitoring of sodium gluconate (SG) fermentation was established for the first time by the equations which can calculate real-time key-parameters by on-line physiological data. Based on this approach, limiting factors were found out in initial fermentation F1 and then step-wise agitation increase and improved medium recipe were proposed in fermentation F2 and F3, respectively. The highest average SG production rate (16.58 ± 0.91 g L−1 h−1) was achieved in fermentation F3, which was 104.2% and 48.0% higher than those in fermentation F1 and F2, respectively. Meanwhile, due to shorter fermentation period (decreased from 34 h to 18.7 h), lower biomass (about 1.5 g L−1) and less by-product accumulation, the overall yield of 0.943 ± 0.012 (mol mol−1) in fermentation F3 increased more than 16.0% compared to fermentation F1. This approach had been successfully applied to industrial fermentation and greatly improved SG production.

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