Production of salicylic acid from naphthalene by immobilized Pseudomonas sp strain NGK1

Abstract

The Pseudomonas sp. strain NGK1 (NCIM 5120) was immobilized in calcium alginate, agar, and polyacrylamide gel matrices. The salicylic acid-producing capacity of freely suspended cells was compared with immobilized cells in batches with a shake culture and continuous culture system in a packed bed reactor. Freely suspended cells (4x10(10) cfu/ml) produced 12 mM of salicylic acid, whereas cells immobilized in calcium alginate (1.8x10(11) cfu/g beads), agar (1.8x10(11) cfu/g beads), and polyacrylamide (1.6x10(11) cfu/g beads) produced 15, 11, and 16 mM of salicylic acid, respectively, from naphthalene at an initial concentration of 25 mM. The continuous production of salicylic acid from naphthalene was investigated in a continuous packed bed reactor with two different cell populations. The longevity of the salicylic acid-producing activity of the immobilized cells from naphthalene was also studied in semicontinuous fermentations. The immobilized cells could be reused 18, 13, and more than 20 times without losing salicylic acid-producing activity in calcium alginate-, agar-, and polyacrylamide-entrapped cells, respectively. The study reveals a more efficient utilization of naphthalene and salicylic acid production by the immobilized Pseudomonas sp. strain NGK1 as compared to the free cells.