Application of 8-parallel micro-bioreactor system with non-invasive optical pH and DO biosensor in high-throughput screening of l-lactic acid producing strain

Application of near-infrared spectroscopy technology in the complex fermentation system to achieve high-efficiency production

The fermentation process is dynamically changing, and the metabolic status can be grasped through real-time monitoring of environmental parameters. In this study, a real-time and on-line monitoring experiment platform for substrates and products detection was developed based on non-contact type near-infrared (NIR) spectroscopy technology. The prediction models for monitoring the fermentation process of lactic acid, sophorolipids (SLs) and sodium gluconate (SG) were established based on partial least-squares regression and internal cross-validation methods. Through fermentation verification, the accuracy and precision of the NIR model for the complex fermentation environments, different rheological properties (uniform system and multi-phase inhomogeneous system) and different parameter types (substrate, product and nutrients) have good applicability, and R2 was greater than 0.98, exhibiting a good linear relationship. The root mean square error of prediction shows that the model has high credibility. Through the control of appropriate glucose concentration in SG fermentation as well as glucose and oil concentrations SLs fermentation by NIR model, the titers of SG and SLs were increased to 11.8% and 26.8%, respectively. Although high cost of NIR spectrometer is a key issue for its wide application in an industrial scale. This work provides a basis for the application of NIR spectroscopy in complex fermentation systems.

Advances in sophorolipid-producing strain performance improvement and fermentation optimization technology

Sophorolipids (SLs), currently one of the most promising biosurfactants, are secondary metabolites produced by many non-pathogenic yeasts, among which Candida bombicola ATCC 22214 is the main sophorolipid-producing strain. SLs have gained much attention since they exhibit anti-tumor, anti-bacterial, anti-inflammatory, and other beneficial biological activities. In addition, as biosurfactants, SLs have a low toxicity level and are easily degradable without polluting the environment. However, the production cost of SLs remains high, which hinders the industrialization process of SL production. This paper describes SL structure and the metabolic pathway of SL synthesis firstly. Furthermore, we analyze factors that contribute to the higher production cost of SLs and summarize current research status on the advancement of SL production based on two aspects: (1) the improvement of strain performance and (2) the optimization of fermentation process. Further prospects of lowering the cost of SL production are also discussed in order to achieve larger-scale SL production with a high yield at a low cost. KEY POINTS: • Review of advances in strain performance improvement and fermentation optimization. • High-throughput screening and metabolic engineering for high-performance strains. • Low-cost substrates and semi-continuous strategies for efficient SL production.

High-Throughput Screening Technology in Industrial Biotechnology

Based on the development of automatic devices and rapid assay methods, various high-throughput screening (HTS) strategies have been established for improving the performance of industrial microorganisms. We discuss the most significant factors that can improve HTS efficiency, including the construction of screening libraries with high diversity and the use of new detection methods to expand the search range and highlight target compounds. We also summarize applications of HTS for enhancing the performance of industrial microorganisms. Current challenges and potential improvements to HTS in industrial biotechnology are discussed in the context of rapid developments in synthetic biology, nanotechnology, and artificial intelligence. Rational integration will be an important driving force for constructing more efficient industrial microorganisms with wider applications in biotechnology.