Characterization of CLA-producing Butyrivibrio spp. reveals strain-specific variations.

Conjugated Linoleic Acid (CLA), a fatty acid with high nutraceutical value is produced in rumen by resident bacterial species, especially Butyrivibrio spp. The present study was undertaken to examine the diversity of indigenous Butyrivibrio spp. from rumen liquor of Indian ruminants. The isolates were screened for their CLA production capability at different level of linoleic acid (LA) (0, 200, 400, 600, 800 μg/ml) at different time intervals (0, 2, 4, 6, 12, and 24 h). A total of more than 300 anaerobic cultures were isolated and 31 of them were identified as Butyrivibrio spp. based on morphological, biochemical and molecular characterization. Further, molecular characterization revealed that a large portion (67.7 %) of isolated Butyrivibrio belonged to Butyrivibrio fibrisolvens (B. fibrisolvens) species which is considered to be the most active bacteria amongst the rumen bacteria populace in terms of CLA production. Bacterial isolate VIII (strain 4a) showed highest CLA production ability (140.77 μg/ml) when incubated at 200 μg/ml LA for 2 h, which is 240 % higher than the isolate XXVII, Butyrivibrio proteoclasticus (B. proteoclasticus) showing lowest CLA production (57.28 μg/ml) amongst the screened isolates. It was evident from the observations recorded during the course of experiments that CLA production ability is strain specific and thus did not follow a single pattern. CLA production also varied with time of incubation and concentration of free linoleic acid supplemented in the growth medium. The results of these findings put forward a strain that is high CLA producer and can be further exploited as an additive for enhancing meat and milk quality in ruminants.