D-Lactate-utilizing bacteria play important roles in maintaining the balance of gut lactate; however, studies on gut D-lactate-uti-lizing bacteria have been limited. This study aimed to isolate and identify D-lactate-utilizing bacteria from pig gut using the Hungate rol-tube method, and to investigate their metabolic characteristicsin vitro. Six different anaerobes were isolated from pig feces, which were identiifed as related toBacteroides fragilis, Bacteroides acidifaciens,Veilonela denticariosi, Veilonela caviae,Bacteroides uniformis, andMegasphaera elsdenibased on the 16S rRNA gene sequences. Al strains had a signiifcant ability to utilize D-lactate, which was concluded afterin vitro fermentation with 25 mmol L–1 D-lactate as the primary carbon source. Of al 6 strains,M. elsdeniJ6 showed the highest efifciency of D-lactate utilization and produced a higher ratio of butyrate in total short chain fatty acids （SCFAs）. Thus, thein vitro fermentation characteristics of this strain in D-, L-, and DL-lactate mixtures （D-lactate：L-lactate=1：1 or 1：2） were further studied. The results showed that M. elsdeni J6 preferred utilizing D-lactate, and produced more SCFA when using D-lactate as the primary carbon source. The ifndings suggest that the administration of D-lactate-utilizing bacteria such asM. elsdeni J6 may have a potential advantage in the aleviation of D-lactic acidosis in the animal gut.
Erhualian and Landrace breeds are typical genetically obese and lean pigs, respectively. To compare the fecal methanogenic Archaeal community between these two pig breeds, fecal samples from different growth phase pigs were collected and used for PCR-denaturing gradient gel electrophoresis （DGGE） with two primer pairs （344fGC/519r and 519f/915rGC） and real-time PCR analysis. Results showed that a better separation and higher quality of bands pattern were obtained in DGGE proifles using primers 344fGC/519r as compared with primers 519f/915rGC. Sequencing of DGGE bands showed that the predominant methanogens in the feces of Erhualian and Landrace pigs belonged to Methanobrevibacter spp. and Methanosphaera spp. Real-time PCR analysis revealed that there was no signiifcant difference in the numbers of fecal total methanogens between Erhualian and Landrace pigs;however, pig growth phase affected the numbers of 16S rRNA genes of total methanogens and Methanobrevibacter smithii. Dissociation curves of methyl coenzyme-M reductase subunit A （mcrA） gene fragments ampliifed with real-time PCR showed all samples possessed a single peak at 82＆#176;C, which might be associated with M. smithii. Samples from the same growth phase of each breed showed good replicative dissociation curves. The results suggest that the growth phase （including diet factor） other than genotype of pig may affect the fecal methanogenic Archaeal community of pigs.
Granulocytes and plasmatocytes play important roles in clearing foreign objects in insects,but it is difficult to distinguish between them in immune reactions.Based on the hemocyte cell line SYSU-OfHe-C established at our lab,two cell sublines,SYSU-OfHe-C Granulocyte(Gr cells)and SYSU-OHe-C Plasmatocyte(PI cells),which possess the morphological characteristics of granulocytes and plasmatocytes,respectively,were established.Gr and PI cells showed different behaviors in immune reactions,such as spreading,phagocytosis and encapsulation.PI cells were easier to spread,but Gr cells tended to undergo aggregation,indicating that they may take different strategies to clear foreign objects.These results also suggested that granulocytes and plasmatocytes may express some different proteins.By comparing the gene expression in cells from the two sublines,1662 differentially expressed genes were identified,and 13 out of 30 transmembrane proteins highly ex pressed in PI cells(six)or Gr cells(seven)were further screened and confirmed by reverse-transcription polymerase chain reaction(PCR).Finally,three transmembrane genes specifically expressed in Pl cells and two transmembrane genes specifically expressed in Gr cells were screened out based on their expressions in immune reactions by quantitative PCR analysis.These genes may potentially be used as molecular markers to distinguish between granulocy tes and plasmatocytes in Ostrinia fiurnacalis,and further to clarify the functions of immune hemocytes in cellular immune reaction such as encapsulation and so on.
