This work presents the study of lactic acid bacteria (LAB) diversity in Thai fermented pork (nham) at different
time points of the fermentation by denaturing gradient gel electrophoresis (DGGE) technique. Total DNA extracted
from two nham samples, fermented with and without Lactobacillus plantarum starter culture, were amplified using
primers targeted at V3 region of the 16S rRNA gene of bacteria. DNA bands appeared on DGGE gels were cloned and
sequenced for species identification. The results showed that the LAB species in both nham samples at the beginning
of fermentation was diverse and at least 15 species were detected. The number of species was then reduced dramatically
during the first 2 days of fermentation. Two main species, i.e. Lactococcus garvieae and Lactococcus lactis were
found from day 2 to day 15. In nham fermented with starter culture, the DGGE band corresponding to the Lb. plantarum
was evident from the beginning to the end of the test period. However, in nham without starter culture, although no Lb.
plantarum was added and no corresponding band appeared at the beginning of fermentation, the band gradually
appeared as faint band on day 3 and increased in intensity as fermentation progressed. Similar pattern was also
observed on the band corresponding to Pediococcus pentosaceus. This phenomenon suggested that Lb. plantarum and
P. pentosaceus can be established successfully and may play an important role in nham fermentation system. This
study also reported co-migration of different DNA species to the same DGGE-band position as well as fragments with
the same DNA sequence may also migrated to different position on the DGGE gel. Therefore, the number of DGGE
bands could not be used to identify the number of bacterial species in the sample accurately.