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Given that probiotics always have host-homologous and strain-specific effects on the hosts, lactic acid bacteria extracted and identified from porcine specimens can be potentially developed as probiotics for pig production. We aimed to identify lactic acid bacteria that are potentially probiotic, have good capacity of inhibiting pathogenic bacteria in intestine and are promising to be used as substitutes for antibiotics in pig production. Potential probiotic strains were extracted from 15 fecal specimens collected from 15 apparently healthy pigs, and were identified via 16S rDNA sequencing. The antimicrobial activity, tolerance to acid and bile salts, Caco-2 cell adhesiveness and susceptibility to antibiotics of the isolates were evaluated in vitro, and oral toxicity of the isolates were evaluated in mice. One Lactiplantibacillus plantarum (BJR2), two Lacticaseibacillus casei (HJD and TH2), one Lacticaseibacillus rhamnosus (MRS1), and two Enterococcus faecium (S-3 and S-4-H) were extracted from healthy pigs and underwent 16S rDNA sequencing identification. L. plantarum BJR2 and L. casei HJD exhibited broad-spectrum and higher antimicrobial activity against indicator enteric pathogens, including Salmonella choleraesuis CVCC 2139, Escherichia coli (O147:K89) CVCC 199, Escherichia coli (O141:K99) CVCC 223 and Escherichia coli (O139) CVCC 1496, among 6 tested strains. In addition, both L. plantarum BJR2 and L. casei HJD exhibited good tolerance to low pH (pH 2.5 and pH 3.5) and 0.30% bile salts, had relatively strong Caco-2 adhesiveness and carried no transferable resistant genes against antibiotics encoded by plasmid. In safety trials, these two isolates had no α or β-hemolysis activity, and were proved safe through oral toxicity tests in mice. It is concluded that L. plantarum BJR2 and L. casei HJD are potential probiotic candidate strains and their probiotic effects need to be further studied in pigs.

The Sox family plays essential roles as transcription factors in vertebrates; however, little is known about the Sox family in Lutraria sieboldii. L. sieboldii are pleasant to eat with a short growth cycle and have become one of the best bottom-seeded enrichment species in Guang Xi. In this study, Sox2 (named LsSox2) and Sox9 (named LsSox9) from L. sieboldii were cloned, and their expression patterns were analyzed. The length of the LsSox2 gene coding sequence was 1011 bp, encoding 336 amino acids, and LsSox9 was 1449 bp, encoding 482 amino acids. LsSox2 had its highest expression levels in the ovary, which were 356 times those in testis, whereas LsSox9 presented higher expression in testis, which was 6 times more highly expressed than in the ovary. LsSox2 exhibited the highest expression during the morula stage, which was 20 times that of the D-shaped larvae or zygote. LsSox9 exhibited two expression peaks, one at the four-cell stage and the other at the trochophore stage, while the lowest expression was in the zygote. LsSox9 was 73 times more highly expressed in the four-cell stage than in the zygote stage. During gonadal development, LsSox2 presented the highest expression in the mature ovary, which was 756 times more highly expressed than in mature testis. LsSox9 presented higher expression in testis at the emission stage which was 6 times more highly expressed than in the ovary. These results indicate that LsSox2 and LsSox9 may play important roles in embryonic and gonadal development.