The thesis reviews different pathways by which certain species within the fungal and bacterial kingdoms degrade Nicotinic acid and its derivatives and use them as a Nitrogen source. Several pathways are observed in bacteria, while very little is known about fungi, with the pathway for Aspergillus nidulans being the only one studied in detail. The observed bacterial pathways include those of Arthrobacter nicotinovorans, several Bacillus species, Pseudomonas putida, Eubacterium barkeri, and some Ochtrobactrum species. The complete degradation leads to the production of Ammonium in each case. These pathways also highlight the involvement and importance of Nicotinic acid in energy production in the cell as it leads to nicotinamide adenine dinucleotide (NAD) which is involved in many energy-creating pathways.