The well-being of farm animals is highly dependent on the prevention of disease outbreaks in husbandry. Numerous environmental stress factors favor the development of pathogenic bacteria that interfere with the composition of commensal microbes in the gastrointestinal tract and induce diseases (Gaggìa et al. 2010). Many infections can be easily transferred from animals to humans by contaminated food of animal origin. One of the most common zoonosis is salmonellosis, which can cause a wide range of illnesses such as fever, sepsis, infections of tissues and inflammation of the gastrointestinal tract. It is often transferred to humans from infected poultry meat (Ryan et al. 2017).
Probiotic bacteria application appears a promising alternative to antibiotics (Musikasang et al. 2009; Carter et al. 2017). Probiotics have the potential of competitive exclusion of pathogens and growth-promoting effects by supporting the absorption of certain essential nutrients, thus increasing total body weight, feed intake, and feed conversion rate (Yeo et al. 2016; Angelakis 2017). Lactic acid bacteria (LAB) are the most common probiotic bacteria used in food fermentation, and in taste and texture enhancement in fermented food products. They are proved to be safe for animals and humans (Vankerckhoven et al. 2008; Mokoena 2017). To consider a strain as a potential probiotic, the strain has to possess certain health-promoting features such as the stimulation of host immune response or modulation of its microbiota (Romani Vestman et al. 2013). However, in the development of a probiotic product, also the safety, functional and technological aspects need to be considered (Hütt et al. 2006; Belicová et al. 2013). Probiotic has to withstand harsh gastrointestinal tract conditions (such as low pH, and presence of bile salts) and be able to adhere to intestinal epithelial cells (Kos et al. 2003; Kaushik et al. 2009; Tinrat et al. 2011).
The recent studies demonstrated that the application of probiotic cultures successfully reduced
The aim of this research was to investigate the probiotic properties of new
Additionally, 126
where At represents the absorbance at time t = 24 h, and A0 the absorbance at time t = 0 h.
The coaggregation was measured for LAB with reference to pathogenic strains of
where Ax and Ay represent absorbance of each of the two strains in the control tubes and Ax+y absorbance of their mixture. Each experiment was performed in triplicate.
Fig. 1.
The survival of lactic acid bacteria at 1% and 2% bile salts.

Fig. 2.
The resistance of LAB to low pH.

Antibiotic resistance of
Antibiotic inhibition zone diameter | ||||||
---|---|---|---|---|---|---|
PEN | KAN | TET | ERY | DOX | AMX | |
| 27 ± 2.5 | 0 | 34 ± 1.0 | 33 ± 2.5 | 32 ± 2.0 | 21 ± 2.1 |
| 28 ± 2.5 | 0 | 30 ± 0.6 | 34 ± 1.5 | 33 ± 1.0 | 24 ± 0.6 |
| 27 ± 6.4 | 0 | 25 ± 1.5 | 25 ± 0.0 | 30 ± 0.6 | 21 ± 1.0 |
Probiotic properties of
Autoaggregation | Coaggregation | Coefficient of adherence to polystyrene | Adherence to Caco-2 cells | |||||
---|---|---|---|---|---|---|---|---|
S. Ent. 13076 | S. Typ. 13311 | S. Typ. 14028 | Init. No. | After 2 h | Adherence index | |||
[log CFU/ml] | ||||||||
| 96.1% ± 1.2% | 14.8% ± 0.01% | 84.2% ± 0.01% | 51.8% ± 0.03% | 1.18 ± 0.02 | 8.5 | 7.6 ± 1.1 | 89.8% |
| 98.2% ± 3.6% | 26.1% ± 0.01% | 58.5% ± 0.01% | −11.1%± 0.01% | 1.22 ± 0.02 | 8.5 | 8.3 ± 0.5 | 98.0% |
| 93.5% ± 0.9% | 41.8% ± 3.4% | 17.8% ± 3.3% | 43.7% ± 2.7% | 1.20 ± 0.07 | 8.0 | 6.3 ± 0.1 | 78.9% |
The coaggregation of LAB strains with three reference
Antagonistic activity of LAB in competition assay – adherence to Caco-2 cells. In the competition test, the antagonistic activity of LAB on the adherence of
Fig. 3.
Adherence of

Fig. 4.
Cytotoxic effect of probiotics’ supernatants on Caco-2 cells in the range of tested dilutions presented as % of control.

Antagonistic activity of
Salmonella sp. strain | Year of Salmonella acquisition |
|
|
|
---|---|---|---|---|
| +++ | +++ | +++ | |
| +++ | +++ | +++ | |
| +++ | +++ | +++ | |
| 2009 | + a | + a | +++ b |
| 2009 | ++ a | + b | ++ a |
| 2010 | + a | + a | ++ b |
| 2010 | + a | ++ a | ++ b |
| 2010 | ++ a | + b | ++ a |
| 2010 | ++ a | + b | ++ a |
| 2010 | + a | + b | + a |
| 2010 | + a | ++ b | + a |
| 2010 | + a | ++ b | + a |
| 2010 | + a | + b | + a |
| 2010 | + b | + a | ++ a |
| 2010 | ++ a | + ab | + b |
| 2010 | + ab | + a | + b |
| 2010 | + | + | + |
| 2010 | ++ a | + ab | + b |
| 2010 | + | + | + |
| 2010 | + | + | + |
| 2009 | ++ a | + ab | + b |
| 2009 | + a | + b | ++ c |
| 2009 | + | + | ++ |
| 2009 | ++ b | + a | + a |
| 2009 | + | + | ++ |
| 2009 | + a | + a | − b |
| 2009 | + | + | + |
| 2009 | + a | − b | + a |
| 2009 | ++ b | + a | − a |
| 2009 | + | + | + |
| 2009 | + a | ++ b | + a |
| 2009 | + b | ++ a | + a |
| 2009 | ++ b | + a | + a |
| 2009 | ++ a | ++ a | + b |
| 2009 | + ab | + a | + b |
| 2009 | + a | − b | + a |
| 2009 | + | + | + |
| 2009 | ++ b | + a | + a |
| 2009 | + a | − b | + a |
| 2009 | + a | + ab | + b |
| 2009 | + b | + a | + a |
| 2009 | + | + | + |
| 2009 | + a | + ab | + b |
| 2009 | ++ a | ++ b | + c |
| 2009 | + | + | + |
| 2009 | ++ a | + b | − c |
| 2009 | a | ++ b | + c |
| 2009 | ++ a | ++ b | + c |
| 2009 | + a | ++ b | + a |
| 2009 | + a | ++ b | ++ ab |
| 2009 | + a | ++ b | + c |
| 2009 | + a | + a | ++ b |
| 2009 | ++ b | ++ a | ++ a |
| 2009 | + | ++ | + |
| 2009 | ++ a | ++ b | ++ c |
| 2009 | ++ ab | ++ a | + b |
| 2009 | ++ a | ++ a | + b |
| 2009 | + ab | ++ a | + b |
| 2009 | + | + | + |
| 2009 | ++ ab | ++ a | ++ b |
| 2014 | + a | ++ ab | ++ b |
| 2014 | + a | ++ b | ++ b |
| 2014 | ++ a | + b | + c |
| 2014 | ++ | ++ | ++ |
| 2014 | + | + | + |
| 2014 | ++ a | + b | ++ a |
| 2009 | ++ a | + b | ++ a |
| 2010 | + b | + a | + a |
| 2014 | ++ a | + a | ++ b |
| 2014 | + b | ++ a | ++ a |
| 2014 | + a | + b | + a |
| 2014 | + a | + b | + a |
| 2014 | + a | + a | ++ b |
| 2014 | + | + | + |
| 2014 | + b | ++ a | ++ a |
| 2014 | + a | ++ ab | ++ b |
| 2014 | ++ a | ++ b | ++ ab |
| 2014 | + a | + a | ++ b |
| 2014 | + a | + a | ++ b |
| 2014 | + a | + a | ++ b |
| 2015 | + a | + a | ++ b |
| 2015 | ++ a | + b | + ab |
| 2015 | ++ | ++ | ++ |
| 2015 | ++ a | + b | + c |
| 2016 | + | + | + |
| 2016 | ++ | ++ | ++ |
| 2016 | + a | + b | ++ a |
| 2016 | + | ++ | + |
| 2016 | + a | + b | ++ c |
| 2016 | + | + | + |
| 2016 | ++ a | ++ ab | + b |
| 2016 | ++ a | + b | + c |
| 2016 | + a | − b | + c |
| 2016 | + a | + b | + a |
| 2016 | + a | - b | + a |
| 2016 | + | + | + |
| 2016 | ++ a | ++ b | ++ c |
| 2016 | ++ | ++ | ++ |
| 2016 | + | + | + |
| 2016 | ++ a | ++ b | + c |
| 2016 | ++ | ++ | ++ |
| 2016 | + a | ++ b | + a |
| 2016 | ++ a | + b | ++ a |
| 2016 | ++ | ++ | + |
| 2016 | ++ a | ++ b | ++ ab |
| 2016 | ++ b | ++ a | ++ a |
| 2016 | ++ | ++ | ++ |
| 2016 | + a | + a | ++ b |
| 2016 | ++ a | +++ b | ++ a |
| 2016 | ++ | +++ | ++ |
| 2016 | + | ++ | + |
| 2016 | ++ a | ++ b | ++ ab |
| 2016 | + b | + a | + a |
| 2016 | ++ a | +++ b | + c |
| 2016 | ++ a | + a | + b |
| 2016 | +++ | +++ | +++ |
| 2013 | ++ a | + b | ++ a |
| 2013 | ++ a | + b | ++ a |
| 2013 | + | + | + |
| 2013 | ++ a | + b | + c |
| 2013 | ++ a | + b | ++ a |
| 2014 | ++ a | ++ b | ++ ab |
| 2014 | + a | + b | + ab |
| 2014 | + a | + a | + b |
| 2014 | + a | + b | + c |
| 2010 | + a | + ab | + b |
| 2013 | ++ a | + ab | + b |
Different superscripts in the same row denote statistically significant differences in antagonistic activity of different
Fig. 5.
Total antagonistic activity index (IAA) of lactic acid bacteria.

The increasing number of evidence demonstrates that probiotics are effective in the prevention and treatment of bacterial diseases in animals. Due to limitations in the application of antibiotics, probiotics may be a promising alternative. It holds especially in case of
Recent methods for
Therefore, lactic acid bacteria strains that reduce or even eliminate
The survival of bacteria in the gastrointestinal tract is highly dependent on bacteria’s resistance to bile salts and low pH (Verdenelli et al. 2009). The tolerance of probiotics strains to increased bile salts concentration is one of the crucial features responsible for their function and stability in the small intestine. Moreover, the high concentration of bile salt can be used as a strong tool for the selection of potential probiotic strains. In this study, all three strains survive under bile salts conditions higher than those observed in the intestinal tract (1% and 2%) even after 4 h of incubation. Moreover,
In the case of pH tolerance, probiotic’s passage through media with low pH is strain-dependent (Belicová et al. 2013). The results of our study also confirmed this observation.
To colonize GIT, probiotic bacteria need to adhere to mucosal surfaces (Tropcheva et al. 2011). It is a multistep process based on non-specific physical interactions between cells and bacteria, which then enable specific interactions between complementary receptors (Kos et al. 2003). Aggregation is the process of reversible gathering of bacterial cells belonging to the same bacterial strain (autoaggregation) or two different bacterial strains (coaggregation). Adhesion is dependent on autoaggregation properties of bacteria, while coaggregation provides close interaction with pathogenic bacteria, in which lactobacilli could release antimicrobial substances in very close proximity. These features also allow probiotics to form a barrier preventing pathogens from colonization (Kos et al. 2003; Janković et al. 2012). All LAB strains tested showed a high autoaggregation rate above 93% observed after 24 h. The coaggregation rate with
One of the most essential features of probiotics is their ability to adhere to intestinal cells and colonize the gastrointestinal tract of the host. Colonization is related to many beneficial effects such as the stimulation of immune system and the prevention of pathogen colonization either by probiotics antagonistic activity towards pathogens or by their competition for a limited number of receptors on the surface of GIT (Cukrowska et al. 2009; Ostad et al. 2009; Verdenelli et al. 2009). Thus, a high rate of adherence to the biotic surface is the desired feature, whereas adherence to the abiotic surface can be problematic in the production of a probiotic formulation. Adherence properties of lactic acid bacteria depend on many factors – especially on the cell wall structure and the individual strain. In this study, the ability of bacteria to form a biofilm on an abiotic surface was examined by measuring the adherence to a polystyrene surface. All strains revealed weak adherence properties with the adherence values ranging from 1.18 ± 0.02 to 1.22 ± 0.02 at 630 nm. Adherence to epithelial cells was assessed by measuring the adherence index of LAB strains to Caco-2 cells. The highest level of adherence was observed for
Another important method, used in this study, was a competition test conducted to observe the stimulation or inhibition of
To assess the cytotoxicity of probiotic’s metabolic products and, thus, to confirm their safety for the application, the NRU assay was performed. No significant cytotoxic effect was detected when compared to control samples. The undiluted supernatant from
As the target application of the described LAB strains for using in poultry farming their susceptibility to antibiotics (penicillin G, tetracycline, erythromycin, and doxycycline) was evaluated. All three strains were found to be resistant to amoxicillin and kanamycin, which is not a rare phenomenon among probiotics as they are naturally resistant to certain antibiotics. Several studies reported lactobacilli intrinsic resistance to kanamycin and amoxicillin (Varankovich et al. 2015; Imperial and Ibana 2016; Wang et al. 2018). In some cases, antibiotic resistance of probiotics could be beneficial due to the accompanying administration of various antimicrobials during animal farming or the application of antibiotic-probiotic combination treatment (Wright et al. 2015). What is more important, the probiotic strains identified in our study belong to species included in the EFSA QPS list.
Finally, the broad antagonistic spectrum against
All tested LAB bacteria revealed the ability to inhibit the growth of most of the environmental strains of
While acting in the gastrointestinal tract, probiotic formulations affect an entire body of the animal. It is known that lactic acid bacteria compete for food and the place of adhesion to the intestinal epithelium with pathogens; however, the mechanisms of this actions are still not fully understood (Trzeciak et al. 2016). Probiotic mixtures seem to have a better effect than single bacteria preparation because they can address a wide spectrum of pathogens and may have synergistic adhesion effects (Verdenelli et al. 2009; Chapman et al. 2011). The synergistic effect on adhesion and antagonistic activity of presented bacteria still need to be evaluated. There is also the requirement for further research that will investigate other properties of studied bacteria such as the presence of antibiotic resistance plasmids, the nature of the antimicrobial agents produced by the bacteria, and the ability to withstand conditions of simulated gastrointestinal tract.
Our results showed that
Fig. 1.

Fig. 2.

Fig. 3.

Fig. 4.

Fig. 5.

Antagonistic activity of Lactobacillus sp. strains against Salmonella sp. (type of inhibition: +++ strong; ++ moderate; + weak; − no inhibition).
Salmonella sp. strain | Year of Salmonella acquisition |
|
|
|
---|---|---|---|---|
|
+++ | +++ | +++ | |
|
+++ | +++ | +++ | |
|
+++ | +++ | +++ | |
|
2009 | +
|
+
|
+++
|
|
2009 | ++
|
+
|
++
|
|
2010 | +
|
+
|
++
|
|
2010 | +
|
++
|
++
|
|
2010 | ++
|
+
|
++
|
|
2010 | ++
|
+
|
++
|
|
2010 | +
|
+
|
+
|
|
2010 | +
|
++
|
+
|
|
2010 | +
|
++
|
+
|
|
2010 | +
|
+
|
+
|
|
2010 | +
|
+
|
++
|
|
2010 | ++
|
+
|
+
|
|
2010 | +
|
+
|
+
|
|
2010 | + | + | + |
|
2010 | ++
|
+
|
+
|
|
2010 | + | + | + |
|
2010 | + | + | + |
|
2009 | ++
|
+
|
+
|
|
2009 | +
|
+
|
++
|
|
2009 | + | + | ++ |
|
2009 | ++
|
+
|
+
|
|
2009 | + | + | ++ |
|
2009 | +
|
+
|
−
|
|
2009 | + | + | + |
|
2009 | +
|
−
|
+
|
|
2009 | ++
|
+
|
−
|
|
2009 | + | + | + |
|
2009 | +
|
++
|
+
|
|
2009 | +
|
++
|
+
|
|
2009 | ++
|
+
|
+
|
|
2009 | ++
|
++
|
+
|
|
2009 | +
|
+
|
+
|
|
2009 | +
|
−
|
+
|
|
2009 | + | + | + |
|
2009 | ++
|
+
|
+
|
|
2009 | +
|
−
|
+
|
|
2009 | +
|
+
|
+
|
|
2009 | +
|
+
|
+
|
|
2009 | + | + | + |
|
2009 | +
|
+
|
+
|
|
2009 | ++
|
++
|
+
|
|
2009 | + | + | + |
|
2009 | ++
|
+
|
−
|
|
2009 | a | ++
|
+
|
|
2009 | ++
|
++
|
+
|
|
2009 | +
|
++
|
+
|
|
2009 | +
|
++
|
++
|
|
2009 | +
|
++
|
+
|
|
2009 | +
|
+
|
++
|
|
2009 | ++
|
++
|
++
|
|
2009 | + | ++ | + |
|
2009 | ++
|
++
|
++
|
|
2009 | ++
|
++
|
+
|
|
2009 | ++
|
++
|
+
|
|
2009 | +
|
++
|
+
|
|
2009 | + | + | + |
|
2009 | ++
|
++
|
++
|
|
2014 | +
|
++
|
++
|
|
2014 | +
|
++
|
++
|
|
2014 | ++
|
+
|
+
|
|
2014 | ++ | ++ | ++ |
|
2014 | + | + | + |
|
2014 | ++
|
+
|
++
|
|
2009 | ++
|
+
|
++
|
|
2010 | +
|
+
|
+
|
|
2014 | ++
|
+
|
++
|
|
2014 | +
|
++
|
++
|
|
2014 | +
|
+
|
+
|
|
2014 | +
|
+
|
+
|
|
2014 | +
|
+
|
++
|
|
2014 | + | + | + |
|
2014 | +
|
++
|
++
|
|
2014 | +
|
++
|
++
|
|
2014 | ++
|
++
|
++
|
|
2014 | +
|
+
|
++
|
|
2014 | +
|
+
|
++
|
|
2014 | +
|
+
|
++
|
|
2015 | +
|
+
|
++
|
|
2015 | ++
|
+
|
+
|
|
2015 | ++ | ++ | ++ |
|
2015 | ++
|
+
|
+
|
|
2016 | + | + | + |
|
2016 | ++ | ++ | ++ |
|
2016 | +
|
+
|
++
|
|
2016 | + | ++ | + |
|
2016 | +
|
+
|
++
|
|
2016 | + | + | + |
|
2016 | ++
|
++
|
+
|
|
2016 | ++
|
+
|
+
|
|
2016 | +
|
−
|
+
|
|
2016 | +
|
+
|
+
|
|
2016 | +
|
-
|
+
|
|
2016 | + | + | + |
|
2016 | ++
|
++
|
++
|
|
2016 | ++ | ++ | ++ |
|
2016 | + | + | + |
|
2016 | ++
|
++
|
+
|
|
2016 | ++ | ++ | ++ |
|
2016 | +
|
++
|
+
|
|
2016 | ++
|
+
|
++
|
|
2016 | ++ | ++ | + |
|
2016 | ++
|
++
|
++
|
|
2016 | ++
|
++
|
++
|
|
2016 | ++ | ++ | ++ |
|
2016 | +
|
+
|
++
|
|
2016 | ++
|
+++
|
++
|
|
2016 | ++ | +++ | ++ |
|
2016 | + | ++ | + |
|
2016 | ++
|
++
|
++
|
|
2016 | +
|
+
|
+
|
|
2016 | ++
|
+++
|
+
|
|
2016 | ++
|
+
|
+
|
|
2016 | +++ | +++ | +++ |
|
2013 | ++
|
+
|
++
|
|
2013 | ++
|
+
|
++
|
|
2013 | + | + | + |
|
2013 | ++
|
+
|
+
|
|
2013 | ++
|
+
|
++
|
|
2014 | ++
|
++
|
++
|
|
2014 | +
|
+
|
+
|
|
2014 | +
|
+
|
+
|
|
2014 | +
|
+
|
+
|
|
2010 | +
|
+
|
+
|
|
2013 | ++
|
+
|
+
|
Probiotic properties of Lactobacillus strains.
Autoaggregation | Coaggregation | Coefficient of adherence to polystyrene | Adherence to Caco-2 cells | |||||
---|---|---|---|---|---|---|---|---|
S. Ent. 13076 | S. Typ. 13311 | S. Typ. 14028 | Init. No. | After 2 h | Adherence index | |||
[log CFU/ml] | ||||||||
|
96.1% ± 1.2% | 14.8% ± 0.01% | 84.2% ± 0.01% | 51.8% ± 0.03% | 1.18 ± 0.02 | 8.5 | 7.6 ± 1.1 | 89.8% |
|
98.2% ± 3.6% | 26.1% ± 0.01% | 58.5% ± 0.01% | −11.1%± 0.01% | 1.22 ± 0.02 | 8.5 | 8.3 ± 0.5 | 98.0% |
|
93.5% ± 0.9% | 41.8% ± 3.4% | 17.8% ± 3.3% | 43.7% ± 2.7% | 1.20 ± 0.07 | 8.0 | 6.3 ± 0.1 | 78.9% |
Antibiotic resistance of Lactobacillus strains.
Antibiotic inhibition zone diameter |
||||||
---|---|---|---|---|---|---|
PEN | KAN | TET | ERY | DOX | AMX | |
|
27 ± 2.5 |
0 |
34 ± 1.0 |
33 ± 2.5 |
32 ± 2.0 |
21 ± 2.1 |
|
28 ± 2.5 |
0 |
30 ± 0.6 |
34 ± 1.5 |
33 ± 1.0 |
24 ± 0.6 |
|
27 ± 6.4 |
0 |
25 ± 1.5 |
25 ± 0.0 |
30 ± 0.6 |
21 ± 1.0 |