from indigenous fermented foods and human gut ... - Thapar University
from indigenous fermented foods and human gut ... - Thapar University
from indigenous fermented foods and human gut ... - Thapar University
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21<br />
Chapter II Review of Literature<br />
approximately 90% of the flora, but in order to be sure of identifying these species some<br />
hundred isolates <strong>from</strong> each sample should be examined. Such bacteria are generally identified<br />
on the base of their morphology as determined by Gram stain, fermentation reactions <strong>and</strong><br />
metabolic tests. While several schemes have been developed for the identification of<br />
<strong>indigenous</strong> anaerobic bacteria, it is still difficult to identify many of these organisms by<br />
conventional tests at species level. Differentiation of major intestinal bacterial groups<br />
according to Gram-staining, aerobic growth, spore production <strong>and</strong> major fermentation<br />
products are presented below in Table 2.3.<br />
The Lactobacillus commonly includes Lactobacillus casei <strong>and</strong> the taxonomically<br />
related species L. paracasei <strong>and</strong> L. rhamnosus. While this group of lactobacilli can be readily<br />
distinguished <strong>from</strong> other members of the Lactobacillus genus by fermentation profiles<br />
(Hammes et al., 1992), it is not possible to unequivocally distinguish between these three<br />
species on the same basis.<br />
The identification of L. casei by polymerase chain reaction (PCR) is important for<br />
basic studies <strong>and</strong> applications in food industries. L. casei along with L. paracasei <strong>and</strong> L.<br />
rhamnosus have very similar physiological properties, nutritional requirements <strong>and</strong> grow<br />
under similar environmental conditions (Mitsuoka, 1992).
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