**3. Importance of** *Lactobacillus* **exopolysaccharides (EPS)**

### **3.1 Health benefits of** *Lactobacillus* **exopolysaccharide (EPS)**

*Lactobacillus* exopolysaccharides though are produced to help the bacteria withstand unfavorable environmental conditions such as desiccation, toxic materials, and osmotic stress [11], their health benefits are far-reaching. These health benefits include.

#### *3.1.1* Lactobacillus *EPS as rotavirus therapeutic agent or oral vaccine adjuvants*

Several studies have shown the importance of *Lactobacillus* EPS in rotavirusinduced diarrhea in children. *Lactobacillus* has shown an ability to suppress the replication of rotavirus through the improvement of the intestinal barrier [12]. This attribute may be linked to the EPS produced by the bacteria. The study by Kim et al. [13], showed a potential rotavirus therapeutic/vaccine adjuvant effect from EPS produced by *Lactobacillus plantarum*. The EPS according to the murine model study caused a reduction in the duration of diarrhea, reduced lesions of the epithelium, reduced replication of the rotavirus in the intestine, and a reduction in the time of recovery of the suckling mice [13].

#### *3.1.2 Antioxidant property*

Basically, free radicals are atoms that can damage cells leading to sickness and aging. Antioxidants are substances that can reduce the reactivity of free radicals through the donation of electrons. A study by Adebayo-Tayo and Fashogbon 2020, revealed that exopolysaccharide from *Lactobacillus.*

*delburecki subsp. bulgaricus* had an antioxidant activity that is comparable to ascorbic acid [14]. Other studies by Tang et al. [15], Silva et al. [16], and Yang et al. [17] all show potential antioxidant effects of *Lactobacillus* exopolysaccharide [15–17]. The antioxidant potential of EPS may be due to the bioactive component in its moiety that is capable of donating hydrogen ions [18].

#### *3.1.3 Anti-cancer activity*

Cancer is an abnormal growth of cells with consequent destruction of other cells and organs leading to death. Cancerous conditions are usually serious medical conditions that require serious attention. Methods for the treatment of cancer which include the use of chemotherapeutic agents, radiation, and surgery are invasive. This is because chemotherapeutics and radiation treatments are non-selective as they destroy both normal and cancerous cells leading to serious adverse effects. Based on these explanations, emphasis is now on natural products with anti-cancer activity as they are most likely to come with minimal adverse effects when compared with other agents. The EPS of *Lactobacillus* has been studied for potential anticancer activity with a lot of promising results. EPS of *Lactobacillus gasseri* showed good anti-proliferative activity against cervical cancer cell lines [19]. EPS of *L. plantarum* caused an increased expression of pro-apoptotic genes in mouse intestinal epithelial cancer [20]. *Lactobacillus kefri* and other *Lactobacillus* strains have shown activity in colorectal cancer [21, 22]. The mechanisms of anti-cancer activity of these EPS are postulated to be through the improvement of immunity, prevention of tumorigenesis, and induction of cancer cell apoptosis [23].

#### *3.1.4 Antimicrobial properties of EPS*

Probiotic bacteria are known to produce antimicrobial substances such as bacteriocin, organic acids, etc. Research from several scientists has shown that *Lactobacillus* EPS possesses antimicrobial properties. *In vitro* study of the antimicrobial property of EPS from *Lactobacillus rhamnosus* isolated from human breast milk showed significant activity against *E.coli* and *Salmonella typhimurium* [24]. Studies by other scientists confirmed the potential antimicrobial properties of EPS from other *Lactobacillus* spp. [25, 26].

#### *3.1.5 Antiviral activity*

The improvement of intestinal health through the use of immunobiotics is quite trending at the moment. Immunobiotics are supplements that contain immunoglobulin combined with probiotics and prebiotics. Immunobiotics protection against viral infection is through enhancement of innate and adaptive immunity that leads to the reduction of the duration of the disease, number of episodes, and viral shedding [27]. Pattern recognition receptors through interaction with EPS allow communication between the immunobiotics and the host. EPS of *Lactobacillus delbrueckii* showed an improved antiviral activity [28]. *L. plantarum* antirotavirus activity has been mentioned earlier [13]. Anti-adenovirus activity from EPS of *Lactobacillus, Leuconostoc,* and *Pediococcus* spp. has been recorded [29]. Another Study using a Swine testicular cell line, showed an inhibitory effect on transmissible gastroenteritis coronavirus infection by EPS from *L. plantarum* [30].

#### *3.1.6 Other medical importance*

These include anti-inflammatory [31], anti-cholesterol [32], Immunostimulatory [33], anti-diabetic properties [34].

### **3.2 The importance of** *Lactobacillus* **EPS in the food and dairy industry**

#### *3.2.1 EPS as a bioflocculant*

Flocculants are agents that can cause the aggregation of dispersed particles in a suspension [35]. This makes the suspended particles easy to remove thus presenting a good mouthfeel of the food product. These flocculants can be grouped into inorganic, organic, and bioflocculants [36]. The use of inorganic and organic flocculants is associated with biological toxicities [36, 37]. These biological toxicities are of serious concern and gave birth to more reliable and biologically friendly bioflocculants. The bioflocculants have the advantages of non-toxicity, biodegradability, and no residual pollution [38]. Studies on the use of *Lactobacillus* exopolysaccharides as a bioflocculant have been carried out with promising results [16, 39].

#### *3.2.2 EPS as biothickner and gelling agent*

Thickeners and gelling agents are usually polysaccharides or protein derivatives. They are usually added to food to increase viscosity and stability while maintaining other desired characteristics of the food product. They are used extensively in dairy

### Lactobacillus *exopolysaccharide: An Untapped Biopolymer DOI: http://dx.doi.org/10.5772/intechopen.104954*

and non-dairy products. The use of *Lactobacillus* EPS as biothickners/gelling agents is shown by the works of [1, 40–42]. *Lactobacillus* EPS are widely used in the dairy industry as thickeners and texturizers with a major function of stabilizing the milk and its constituents [43].

### *3.2.3 EPS as a meat preservative and quality enhancer*

The use of lactic acid bacteria to preserve meat is an old practice that has extensively helped in the sustenance of the food industry. These bacteria carry out this preservation through the production of antibacterial substances such as acetic acid, lactic acid, and bacteriocin. They also compete with other food spoilage pathogens for available nutritional substances hence the survival of the fittest. Another wonderful attribute of Lactic acid bacteria is their ability to produce EPS. This EPS is known to protect the bacteria against environmental stress such as high salt concentration, low PH, and low water activity [44]. This protection is known to sustain the preservative ability of LAB. The EPS is also known to reduce fat in the meat. The health importance of reduced fat in meat cannot be over-emphasized. This has led to a growing demand by consumers for fat-reduced meat. A study by Hilbig et al. [45] reported that EPS matrices formed by LAB in certain German meat products were able to cause a fat reduction and improved the quality of the meat product [45].


#### **Table 1.**

*The medical and industrial application of* Lactobacillus *EPS.*

#### *3.2.4 Exopolysaccharide as an inhibitor of syneresis*

Syneresis is the expulsion of a liquid from a gel. It has been shown to affect food and food products negatively. This phenomenon known as syneresis should be minimized in food products without affecting the inert property of the food product. *Lactobacillus* exopolysaccharide according to the study was able to prevent syneresis in starch [46]. Other studies by Lynch et al. [47] and Han et al. [48] gave vivid importance to the syneresis preventive ability of exopolysaccharides produced by lactic acid bacteria [47, 48]. The exopolysaccharide's ability to prevent syneresis is because of its inert high water-binding affinity. This will then make water be retained in the food or dairy product (**Table 1**).

## **4. Challenges facing the industrial applications of EPS**

#### **4.1 Poor yield of the EPS by** *Lactobacillus* **spp.**

The major challenge facing the industrial and medical applications of *Lactobacillus* exopolysaccharides is the poor production of the polymer by the bacteria. It is therefore very important that critical and intensified scientific experiments geared towards solving this problem be prioritized. This is because of the obvious importance of this EPS in medicine and industry. We strongly believe that the ability of the scientific community to solve this problem of poor yield rest on intensified scientific research. However, several types of research have been conducted and some are ongoing towards finding ways of improving the yield of this very important polymer [57–60].

#### **4.2 Difficulty in isolation and characterization**

The methods of extraction and characterization pose serious challenges to the industrial applications of EPS. There are several methods for the extraction of EPS from LAB. However, the physico-chemical properties of this polymeric substance can be affected by the method adopted [61]. The extraction and isolation of EPS usually involve the use of organic solvents, enzymes, sugars, filtration, chromatographic procedures, dialysis, etc. [62]. In all these, the most important thing is to target a high yield of pure EPS utilizing cheaper processes. To achieve this some important aspects of the process are taken into consideration namely the removal of proteins to avoid co-precipitation with EPS, and the prevention of reaction of the EPS with the solvents and components of the medium [61]. Since it is common knowledge that the major challenge of full industrial utilization of EPS is poor yield, there is, therefore, a need to adopt the best strategy for maximal extraction and characterization of the small quantity released by the bacteria. However, this process according to Badel et al. [63] is very laborious and indeed challenging [63].
