Detection and characterization of Lactobacillus spp. in the porcine seminal plasma and their influence on boar semen quality

Abstract

The presence of pathogenic bacteria in ejaculates has been a topic in boar semen preservation over the last decades. Since little information is available on commensal bacteria in boar semen, the aim of the present study was to identify commensal lactobacilli in fresh cryopreserved boar semen and to examine their influence on boar semen quality. Therefore, 111 boar ejaculates were investigated for the presence of Lactobacillus species. Thirty samples (27%) contained viable Lactobacillus species (e.g. L. amylovorus, L. animalis, L. reuteri and Weisella minor). L. animalis and L. buchneri DSM 32407 (isolated from the bovine uterus) qualified for further examinations based on their growth rate in six antibiotic-free boar semen extenders. After a 120 min short-term incubation with an antibiotic-free BTS-extender, progressive motility was diminished (P = 0.001) upon addition of 105 and 106 colony forming units (CFU/mL) L. animalis. The supplementation with L. buchneri DSM 32407 had no significant (P > 0.05) influence on sperm quality during short-term co-incubation. After 168 h long-term co-incubation, motility analysis revealed a negative (P = 0.026) impact of 105 CFU/mL L. buchneri DSM 32407. A concentration- and storage-dependent effect is particularly obvious (P < 0.001) using 106 CFU/mL L. buchneri DSM 32407. Most notably, the thermo-resistance (TRT) for 106 CFU/mL L. buchneri DSM 32407 (P = 0.001) was inferior to BTS with and without gentamicin after 72 and 168 h of semen co-incubation. The supplementation of 105 CFU/mL L. buchneri DSM 32407 impaired progressive motility to a lesser extent. The percentage of mitochondrially active spermatozoa after 96 h (P = 0.009) and membrane-intact spermatozoa after 168 h (P < 0.001) was lower when 106 CFU/mL L. buchneri DSM 32407 were suspended compared with all other groups. Finally, the addition of L. buchneri DSM 32407 to BTS-extended boar semen had no competitive effect on the total amount of bacteria 48 h after co-incubation. In summary, the present study demonstrated that there are Lactobacillus species present in the porcine seminal plasma, which can be cultivated using standard procedures. However, long-term co-incubation of lactic acid bacteria with spermatozoa had a negative influence on spermatozoa.

Bacteria and Boar Semen Storage: Progress and Challenges

“…Mitochondrial membrane potential has also been associated with bacterial concentration and storage time [ 36 ]. Finally, other studies have demonstrated that bacteria cause agglutination of the cells, preventing the correct mobilization of the spermatozoa [ 31 , 33 , 37 , 38 ]. This agglutination is associated with type 1 fimbriae in some bacteria, which bind to glycoprotein receptors on sperm cell surfaces.…”

Sperm success and immunity

“…This system is activated by small molecular motifs conserved in pathogens, such as bacterial lipopolysaccharides and peptidoglycans, and depends on receptors present on immune cells, particularly Toll-like receptors in mammals and peptidoglycan recognition proteins in insects (e.g., reviewed in Dziarski & Gupta, 2006;Kurata, 2014;Sheldon, Owens, & Turner, 2017). Such molecular motifs are not present on the surface of sperm, but bacteria are commonly introduced to the female tract by the male during mating (Cottell et al, 2000;Schulze et al, 2018;Sidaway, 2016) and could trigger an innate immune response. In addition to inflammatory responses triggered by incidentally introduced microbes, cells of the Drosophila female tract, as well as mucosal epithelial cells and neutrophils of the mammalian female tract, produce antimicrobial peptides that can kill some bacteria and viruses (Amjadi et al, 2014).…”

In Vitro Effects of Tea Tree Oil (Melaleuca Alternifolia Essential Oil) and its Principal Component Terpinen-4-ol on Swine Spermatozoa

“…Despite the efforts, liquid phase preservation (16 ± 1 °C) of boar AI doses is still the most common storage technique [3]. In this case, antibiotics are essential to limit bacterial growth [6], as this determines alterations to the midpiece, acrosome, and plasma membrane of the spermatozoa leading to worse quality parameters [7,8]. Moreover, the European Union (Council Directive 90/429/EEC) [9] dictates the use of antibiotics in swine seminal AI doses as mandatory to prevent the spreading of diseases.…”