Genetic engineering techniques are being used to develop microbial strains that can more efficiently ferment substrates to produce desired products through fermentation. Specific genes can be inserted, deleted or replaced to give microbes new properties or abilities. For example, lactic acid bacteria have been engineered to contain only one type of lactic acid dehydrogenase, allowing the pure production of either L-lactic acid or D-lactic acid. New fermentation technologies and bioreactor designs are also being developed to improve process efficiency and product quality and yields.

1. Advances in Food and Beverage Fermentation
1. Engineering of microorganisms for improved fermentation
• Development through genetic techniques of robust proprietary
microorganisms that can better ferment substrates to produce the
desired products.
• Engineering of innovative microbial strains that can help produce
biomolecules in bulk using improved technologies These developments
are indicative of the huge potential of fermentation as a low-cost and
flexible method of producing a range of end products.
• Recombinant DNA technology can be used to genetically improve
bacterial strains for use in industrial processes. Specific genes can be
partially or totally eliminated from a strain or replaced with different
alleles from other strains of the same genus. Likewise, new properties
can be introduced into a strain by gene transfer.

2. Advances in Food and Beverage Fermentation
2. Metabolic pathway engineering of various enzymes
Lactic acid production is dependent on lactate dehydrogenase
(LDH) activities present in lactic acid bacateria. The lactic acid
stereoisomerism is, in general, controlled by the enzymatic activity
of LDH-L or LDH-D, although, in some cases, lactate racemases
have been detected. Hence, lactic acid bacteria that contain only
one of these LDH enzymes may produce a pure enantiomer.
Lactobacillus helveticus has been the first lactic acid bacterium to
be used and combined with LDH-D inactivation, a derivative
developed that was able to produce pure L-lactic acid. By using a
similar approach, pure enantiomers of lactic acid have also been
obtained by the inactivation of specific LDH in other lactic acid
bacteria.

3. Advances in Food and Beverage Fermentation
3. Improvement of the rheological properties of fermentation
broths.
4. Development of more efficient process-driven technologies
Examples: solid-state fermentation, consolidated bioprocessing,
ultrasonication, syngas fermentation, and dark fermentation
5. New bioreactor designs
Examples: High-mass transfer chemical reactors for methanotroph
fermentation and versatile tray-type solid-state fermentation
bioreactors