**Acknowledgements**

*New Advances on Fermentation Processes*

**fermentation**

are guaranteed.

frequencies [30].

operation

**3. Optimising fermentation processes: impact of technology on** 

Technology was coupled to fermentation making possible large-scale production for commercial purposes. Thus, the development of modern engineering, biotechnology and related advanced techniques has connected traditional food fermentations with large-scale production approaches, in which product quality and safety

To obtain better integrated functions of microbial cells and enzymes, evolutionary engineering combined with other biotechnologies has attracted more attention in recent years. Classical laboratory evolution has not only been proven effective to letting more beneficial mutations occur affecting different genes but also has some inherent limitations such as a long evolutionary period and uncontrolled mutation

With the arrival of 'genomics *era*' (genomics, transcriptomics, metagenomics, metabolomics, proteomics, etc.) and 'synthetic biology' approaches, new ways of exploring fermentation are possible due to the possibility of selecting markers and improving cellular transformation strategies [31]. Thanks to these molecular biology approaches, the production of biomolecules through fermentation at large scale

The development of fermentation technology is still being carried out in all aspects. This is intended to improve the yield and quality of products, reducing the costs of production and looking for processes environmentally friendly. Increasing fermentation products can be done by optimising the factors that influence the process from the aspect of the microbe itself, the environment and the technological facilities. Among these factors, the following have promoted optimization [33]:

i.Type of feeding of the bioreactor: batch, fed-batch and continuous mode of

v.Characteristics of inoculation and incubation: ratio of inoculation, agitation

Other approaches combine microbes and technology at micro-/nanoscale. This is the case of strategies based on electrochemistry, which have been reported as successful approaches, mainly in wastewater and sludge treatments [34].

As mentioned before, fermentation sustains many processes in food and bever-

age production at global scale as well as other processes like the production of marketed biocompounds: antibiotics, hormones, pigments, bioplastics, etc. Despite the intensive research efforts on fermentation-based processes, which involve various scientific areas such as plant/microorganism genetics, biochemistry, biomass chemistry and process engineering, the progress of the global use of fermentation has interesting challenges to address in the next future. This is particularly

ii.Nature of fermentation: one or more than one step; solid vs. liquid

iv.Oxygen availability: aerobic, microaerobic and anaerobic processes

iii.Type of microbial cells: single strain or mixed culture processes

rate (to optimise mixing), and continuous control of pH

**4. Challenges related to fermentation for the next future**

is more efficient, low time-consuming and low cost [32].

**6**

The author is thankful to MINECO Spain (RTI2018-099860-B-I00) and University of Alicante (VIGROB-309) for the funding.
