**4. Microbial bioprocesses for obtaining organic acids based on lactose**

Like other renewable sources based on residual plant biomass from agricultural productions rich in complex polysaccharides, lactose has been used as a starting raw material to establish bioprocesses to produce different organic acids. Although there are microbial enzymes capable of breaking the bonds of polysaccharides, this would involve energy and time, which in the case of lactose would be less complicated and faster. In the case of lactose, this could become the starting material for

**Figure 3.** *Some of the organic acids that can be obtained microbially from lactose or whey.*


**61**

(**Figure 4**).

*Bioconversion of Lactose from Cheese Whey to Organic Acids*

**Name Source Microorganism(s) Culture conditions and** 

Milk *Escherichia coli* K-12 Stationary culture for 72 h at

CW *Pseudomonas taetrolens* Aerobic, + Glu, 30°C,

CW *Aspergillus niger* ATCC9642 Aerobic, +15% sucrose,

CW *Pseudomonas taetrolens* Aerobic, 30 °C, + Gly,

CW Aerobic, + Lac, 30°C,

Lac *Lactococcus lactis* Anaerobic, 1%

*WP: whey permeate; PWP: powder whey permeate; CW: cheese whey; SCW: sweet cheese whey; SWP: sweet whey powder; CCW: concentrate cheese whey; HCW: hydrolysate cheese whey; Gal: galactose; Gly: glycerol; Glu: glucose;* 

*Streptococcus zooepidemicus* Aerobic (1 vvm), 37°C,

**production results\***

DW

,

,

,

nisin,

37°C, 168 mg g<sup>−</sup><sup>1</sup>

aeration: 1 L min<sup>−</sup><sup>1</sup>

8.8 g L<sup>−</sup><sup>1</sup>

78 g L<sup>−</sup><sup>1</sup>

100 g L<sup>−</sup><sup>1</sup>

350–500 rpm, pH 6.5,

30°C, 16 h, 106 g L<sup>−</sup><sup>1</sup>

aeration: 1 L min<sup>−</sup><sup>1</sup>

aeration: 1 L min<sup>−</sup><sup>1</sup>

350–500 rpm, pH 6.5,

pH 6.7 and 500 rpm

Lac + 10 ng mL<sup>−</sup><sup>1</sup>

30°C, 24 h (12 h after induction), 0.6 g L<sup>−</sup><sup>1</sup>

350–500 rpm, pH 6.5,

**Ref.**

[160]

[161]

[162]

[161]

[163]

[164]

the production by microbial bioprocesses, not only of the most demanded organic acids today but of other less-used ones that still not as highly in demand. However, subsequent studies must be carried out to make these technologies a viable and

*Characteristics of some organic acids produced by bioconversion of lactose from commercial products or* 

Nowadays, however, some organic acids can be obtained by microbial bioprocesses directly from lactose (**Figure 3**), cheese whey, or both, using the different routes of their metabolisms (**Table 1**). The most demanded organic acids, like citric, acetic, and lactic acids, have been produced from whey (**Table 1**). Even more complex organic acids like poly-lactic and hyaluronic acids can also be produced from lactose. Another advantage of microbial production is related to the possibility of producing the racemic biological active acids exclusively. L-lactic acid is produced almost exclusively by lactic-acid bacterium *Lactobacillus casei* or L-ascorbic acid (vitamin C) by certain recombinant yeast strains of *Kluyveromyces lactis* or *Saccharomyces cerevisiae* [148, 149]. However, for some of the organic acids, the titers reached are still too low for these bioprocesses to be scaled to industrial production in an economically feasible way, and the chemical synthesis remains the most desired choice. At the industrial scale, to produce organic acids competitively, it would be necessary to have adequate sources of *raw materials* (cheap and renewable) and enhanced *microbial strains* (easy and safe to handle and able to work at high productivity). Also, it would be necessary to dispose of industrial facilities and technical expertise (*technical constrains*) to achieve it

*DOI: http://dx.doi.org/10.5772/intechopen.92766*

Malic acid, C4H6O5

Citric acid, C6H8O7

Lactobionic acid, C12H22O12

Hyaluronic acid, (C14H21NO11)n

*agro-industrial by-products.*

**Table 1.**

Gluconic acid, C6H12O7

economically attractive alternative [3, 19].

CCW, HCW

*Lac: lactose; YE: yeast extract; HDT: hydraulic detection time. \*In terms of concentration, yield, and/or productivity of the acid.*



*WP: whey permeate; PWP: powder whey permeate; CW: cheese whey; SCW: sweet cheese whey; SWP: sweet whey powder; CCW: concentrate cheese whey; HCW: hydrolysate cheese whey; Gal: galactose; Gly: glycerol; Glu: glucose; Lac: lactose; YE: yeast extract; HDT: hydraulic detection time. \*In terms of concentration, yield, and/or productivity of the acid.*

#### **Table 1.**

*Lactose and Lactose Derivatives*

Acetic acid, C2H4O2

Acrylic acid, C3H4O2

L-Ascorbic acid, C6H8O6

Propionic acid, C3H6O2

Lactic acid, C3H6O3

Butyric acid, C4H8O2

Succinic acid, C4H6O4

**Name Source Microorganism(s) Culture conditions and** 

WP *Acetobacter aceti* Aerobic, continuous

CW *Lactobacillus acidophilus* Anaerobic, 37°C, 72 h,

SCW *Clostridium propionicum* Anaerobic, +propanoic and

CW *Kluyveromyces lactis* Aerobic, shake-flask, 48 h,

CW *P. acidipropionici* Anaerobic facultative,

SWP *Lactobacillus casei* Anaerobic, 36 h, pH 6.5,

SWP *Lactobacillus rhamnosus* Anaerobic, 37°C, pH 6.2,

CW *Lactobacillus acidophilus* Anaerobic, 37°C, 72 h,

CW *Clostridium beijerinckii* Anaerobic, 37°C, pH 5.5,

CW *Clostridium butyricum* Anaerobic, + 5 g L<sup>−</sup><sup>1</sup>

CW *Actinobacillus succinogenes* Anaerobic+CO2, 38°C,

PWP *Enterobacter* sp. LU1 Microaerobic, + Gly, 34°C,

WP *Clostridium thermolacticum* and *Moorella thermoautotrophica*

CW *Propionibacterium acidipropionici*

Gal *Saccharomyces cerevisiae*

SWP *Propionibacterium acidipropionici*

*Zygosaccharomyces bailii*

*Propionibacterium freudenreichii*

CW Mixed culture of acetogenic and fermentative bacteria

CW *Anaerobiospirillum succiniciproducens*

**production results\***

98 mM

96.9 g L<sup>−</sup><sup>1</sup>

4.82 g L<sup>−</sup><sup>1</sup>

acid

Anaerobic, batch, 58°C, pH 7.2, 300 h, 0.81 g g<sup>−</sup><sup>1</sup>

membrane bioreactor, at 303 K, D = 0.141 h<sup>−</sup><sup>1</sup>

h<sup>−</sup><sup>1</sup>

Anaerobic, batch, 35°C, pH 6.5, 78 h, 0.11 g L<sup>−</sup><sup>1</sup>

acetic acids, 33°C, pH 7.1, 0.133 mmol g<sup>−</sup><sup>1</sup>

Aerobic, shake-flask,144 h,

Anaerobic, fibrous bed bioreactor (immobilized cells),

, 70 mg L<sup>−</sup><sup>1</sup>

acid + 0.33 g L<sup>−</sup><sup>1</sup>

pH 6.5, 7 g L<sup>−</sup><sup>1</sup>

30°C, 30 mg L<sup>−</sup><sup>1</sup>

30°C,0.40 g g<sup>−</sup><sup>1</sup>

135 ± 6.5 g L<sup>−</sup><sup>1</sup>

Anaerobic, 8.2 g L<sup>−</sup><sup>1</sup>

37°C, 33.73 g L<sup>−</sup><sup>1</sup>

pH 6.5, 42.62 g L<sup>−</sup><sup>1</sup>

0.08 g L<sup>−</sup><sup>1</sup>

or + 50 μg L<sup>−</sup><sup>1</sup>

pH 6.5, 19 g L<sup>−</sup><sup>1</sup>

Dark anaerobic, 35°C, HDT = 1 day, 10.6 g L<sup>−</sup><sup>1</sup>

> h<sup>−</sup><sup>1</sup> , 12 g L<sup>−</sup><sup>1</sup>

Anaerobic+CO2, + Glu, pH 6.5, 39°C, 36 h, 16.5 g L<sup>−</sup><sup>1</sup>

pH 6.8, 48 h,28 g L<sup>−</sup><sup>1</sup>

pH 7, 288 h, 69 g L<sup>−</sup><sup>1</sup>

h<sup>−</sup><sup>1</sup>

0.44 g L<sup>−</sup><sup>1</sup>

, 0.33 g L<sup>−</sup><sup>1</sup>

200 rpm, 50 h, 143.7 g L<sup>−</sup><sup>1</sup>

6.1 g L<sup>−</sup><sup>1</sup>

CW *P. acidipropionici* Anaerobic, 0.33 g L<sup>−</sup><sup>1</sup> [145]

, 0.98 g g<sup>−</sup><sup>1</sup> , ,

,

propionic

acetic

**Ref.**

[140, 141]

[142– 144]

[145]

[146]

[147]

[148]

[149]

[150]

[151]

[152]

[153]

[146]

[154]

[155]

[156]

[157]

[158]

[159]

day<sup>−</sup><sup>1</sup>

YE

h<sup>−</sup><sup>1</sup>

,

biotin, 37°C,

**60**

*Characteristics of some organic acids produced by bioconversion of lactose from commercial products or agro-industrial by-products.*

the production by microbial bioprocesses, not only of the most demanded organic acids today but of other less-used ones that still not as highly in demand. However, subsequent studies must be carried out to make these technologies a viable and economically attractive alternative [3, 19].

Nowadays, however, some organic acids can be obtained by microbial bioprocesses directly from lactose (**Figure 3**), cheese whey, or both, using the different routes of their metabolisms (**Table 1**). The most demanded organic acids, like citric, acetic, and lactic acids, have been produced from whey (**Table 1**). Even more complex organic acids like poly-lactic and hyaluronic acids can also be produced from lactose. Another advantage of microbial production is related to the possibility of producing the racemic biological active acids exclusively. L-lactic acid is produced almost exclusively by lactic-acid bacterium *Lactobacillus casei* or L-ascorbic acid (vitamin C) by certain recombinant yeast strains of *Kluyveromyces lactis* or *Saccharomyces cerevisiae* [148, 149]. However, for some of the organic acids, the titers reached are still too low for these bioprocesses to be scaled to industrial production in an economically feasible way, and the chemical synthesis remains the most desired choice. At the industrial scale, to produce organic acids competitively, it would be necessary to have adequate sources of *raw materials* (cheap and renewable) and enhanced *microbial strains* (easy and safe to handle and able to work at high productivity). Also, it would be necessary to dispose of industrial facilities and technical expertise (*technical constrains*) to achieve it (**Figure 4**).

**Figure 4.**

*Successful commercial production of organic acids by microbial biotransformations: keys to success.*

#### **Figure 5.**

*Some of the microbial metabolic pathways for the synthesis of organic acids.*

The microbial bioprocesses could be enhanced through optimization of upand downstream processes that must be combined with metabolic engineering to increase productivity. Also, genetic engineering techniques could be used to obtain

**63**

**Author details**

**Acknowledgements**

José Manuel Pais-Chanfrau1

Ibarra, Imbabura, Ecuador

Quito, Pichincha, Ecuador

Rosario del Carmen Espin-Valladares1

\*Address all correspondence to: jmpais@utn.edu.ec

provided the original work is properly cited.

and Luis Enrique Trujillo-Toledo2

\*, Jimmy Núñez-Pérez1

their faculty, respectively, for their support for this publication.

1 North-Technical University, Universidad Técnica del Norte, UTN, FICAYA,

2 University of the Armed Forces, Universidad de las Fuerzas Armadas, ESPE,

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

,

, Marcos Vinicio Lara-Fiallos1

*Bioconversion of Lactose from Cheese Whey to Organic Acids*

robust industrial strains that raise the expression levels of the genes involved in the metabolic pathways of synthesis of organic acids or repress others that deviate to

Some of the identified metabolic pathways are associated with the tricarboxylic acid (TCA) cycle and demonstrate that most organic acids represent metabolites associated or partially associated with growth (**Figure 5**). A detailed study of these pathways can address the overexpression of some genes or repression of others

Organic acids constitute a market with a sustained increase at present. Many of them are produced on a large scale by chemical synthesis from petroleum derivatives. Still, more recently, other alternatives, cheap and renewable sources of raw materials, are being intensively studied, among which is whey. This trend will be reinforced soon, which, together with the improvement of microbial processes, will allow more and more bioprocesses to appear at the large scale, which will become the trend of this market in the future. Among the countries whose territories contain the majority of the companies dedicated to supplying the world demand for organic acids, the People's Republic of China stands out, which is expected to continue to be the country that will dominate this market in the coming years.

The authors wish to express their gratitude to the authorities of the Universidad Técnica del Norte (UTN, Ibarra, Imbabura, Ecuador) for their unconditional support, and to Dr. Bolívar Batallas and Dr. Hernán Cadenas, Dean and Vice-Dean of

*DOI: http://dx.doi.org/10.5772/intechopen.92766*

produce unwanted by-products [164, 165].

using genetic engineering techniques.

**5. Conclusion**

*Bioconversion of Lactose from Cheese Whey to Organic Acids DOI: http://dx.doi.org/10.5772/intechopen.92766*

robust industrial strains that raise the expression levels of the genes involved in the metabolic pathways of synthesis of organic acids or repress others that deviate to produce unwanted by-products [164, 165].

Some of the identified metabolic pathways are associated with the tricarboxylic acid (TCA) cycle and demonstrate that most organic acids represent metabolites associated or partially associated with growth (**Figure 5**). A detailed study of these pathways can address the overexpression of some genes or repression of others using genetic engineering techniques.
