Cryopreservation induces oxidative stress on sperm due to an increase in the number of reactive oxygen species (ROS), thereby resulting in decreased sperm quality. ROS's destructive potential is normally counteracted in sperm by their innate antioxidant system consisting of enzymes, which include superoxide dismutase (SOD). This study aimed to assess the quality of semen from Itik Pinas-Khaki (IP-Khaki) drakes that were cryopreserved with either 4.5% DMSO or 7.0% glycerol as cryoprotectant through evaluation of total sperm motility (%) and determination of SOD activity (U/mL). Here, semen samples were collected from 12 sexually mature IP-Khaki drakes, an improved egg-type breed of Philippine mallard duck, and processed using modified reported cryopreservation procedure for ducks. Results showed that post-thawing total sperm motility averages of 12.04±5.61% using 4.5% DMSO and 13.99±5.28% using 7.0% glycerol were comparable. Moreover, similar SOD activity levels of 0.39±0.18 U/mL with 4.5% DMSO and 0.33±0.21 U/mL with 7.0% glycerol in 2.00 x 108 IP-Khaki sperm cells were also observed. The observed very low intracellular SOD activity indicates severe damage to sperm cells due to cryopreservation, which resulted in a comparably low total sperm motility with either of the cryoprotectants. Thus, the cryopreservation protocol used is not the optimum for IP-Khaki semen based on the observed considerable decline in sperm motility and very low SOD activity after cryopreservation.

Lactic acid bacteria (LAB) are a diverse group of microorganisms that can be found in natural habitats and are used in a wide range of industries, especially in the food sector. They are regarded "Generally Recognized as Safe" and are commonly used as a starter culture, probiotics, and biopreservative. However, some LAB genera are excluded from the "Qualified Presumption of Safety" (QPS) list due to the possibility that they have virulence and antibiotic resistance genetic determinants. The objective of this study was to investigate the beneficial, virulence, and antibiotic resistance-related genes in 10 well-characterized bacteriocinogenic LAB strains. The auto-aggregation, co-aggregation, cell surface hydrophobicity, and bile salt tolerance were also evaluated to examine their potential as bacteriocinogenic probiotics and/or starter culture. Results showed that all tested strains showed abilities for auto-aggregation at 4oC and 37oC, co-aggregation with S. aureus JCM8704, S. typhimurium BIOTECH1826, and E. coli DH5α, and significant cell-surface hydrophobicity. However, only a few strains were able to withstand the media treated with 0.3% bile salt. Among the tested bacteriocinogenic LAB strains, L. lactis IO-1 and C. divergens V41 had the maximum values for auto-aggregation at 4oC and 37oC, respectively. C. divergens V41 also exhibited the highest percentage for cell surface hydrophobicity. E. faecium NKR-5-3 showed the highest co-aggregation percentages with all indicator strains. Our findings also showed that the tested isolates presented distinct combinations of virulence-related genes. Only two of ten bacteriocinogenic LAB strains exhibited presence of multiple virulence genes. Lactococcus sp. QU12 was found to have a high frequency of beneficial and virulence genes, with 2 out of 7 genes present encoding beneficial factor and 11 out of 13 genes encoding virulence factor. Lactococcus sp. QU12 and L. lactis IO-1 were also positive for tetracycline resistance gene tetM and aminoglycoside resistance gene aphA-2, respectively, and transposon genes. Moreover, only a few LAB isolates tested positive for 2 out of 8 antibiotic resistance classes. Although few, the substantial danger of these genes being transferred and acquired cannot be overlooked as this could potentially cause serious health concerns in the future. These results suggest that despite the promising properties of bacteriocinogenic LAB, careful safety evaluation of these strains should be a prerequisite before using these in food systems.

Lactobacilli are widespread microorganisms and are broadly employed in a variety of applications. It is one of the LAB genera that has been designated as Generally Regarded as Safe (GRAS) and many of its member species are included in the Qualified Presumption of Safety (QPS) list. Lactobacillus is commonly utilized as a starter culture in many fermented food products, probiotics, and has long been used as natural bio-preservatives to increase shelf life and improve food quality and safety. Aside from the many benefits, it delivers in the food sector, the use of lactobacillus strains in the clinical setting as a prophylactic and/or treatment for a variety of diseases has gained increasing attention. These uses of lactobacillus are all made possible through the diverse bioactive molecules it generates. Lactobacillus exerts its positive health and nutritional effects through a variety of mechanisms, including inhibition of pathogen adhesion or colonization, metabolic activity through the synthesis of metabolites and enzymes, and immune system modulation among others. The ability of many lactobacillus strains to mediate the bio-conversion of certain metabolites has also been shown in numerous studies. This chapter describes the recent findings on the impact of the diverse bioactive molecules produced by different lactobacillus strains, their mode of action, and their application in different industries.