Isolation, screening, and molecular identification of pectinase producers from fruits, vegetables, and soil samples

Abstract

Background and objective In this work, isolation, identification (morphological and chemical), and molecular characterization were done of local isolates of some pectinase-producing microorganisms such as bacteria, actinomycetes, fungi, and yeast. Materials and methods A total of 22 local bacterial isolates were obtained from various sources and were assayed for pectinolytic activity after optimization of conditions for pectinase production. Isolate no. 19 showed the highest pectinase-specific activity (6.73 U/ml) on glucose-supplemented medium, whereas isolate no. 5 gave the lowest pectinase productivity (3.21 U/ml). The identification of isolate no. 19 revealed that it belonged to the genus Bacillus based on morphological and biochemical characteristics. Based on molecular identification (16 S rRNA technique), isolate no. 19 was named Bacillus sp. strain NRBANKI-4 (with 99% similarity), with Gene Bank accession number OM540351. Results and conclusion A total of 14 local actinomycete isolates were obtained from soil samples. Isolate no. 13 showed the highest pectinase-specific activity (6.48 U/ml), whereas sample no. 10 gave the lowest pectinase-specific activity (3.07 U/ml). Based on molecular identification (16 S rRNA technique), isolate no. 13 was named Streptomyces sp. KP 12 (90.63% similarity), with Gene Bank accession number OM403596. A total of 10 fungal isolates were obtained from crop waste soil. Isolate no. 2 gave the highest pectinase productivity (21.20 U/ml). Based on molecular identification (internal transcribed spacer-PCR technique), isolate no. 2 was named Aspergillus niger F8121 (99.47% similarity), with Gene Bank accession number OM392061. Following the same trend, 10 yeast isolates were isolated from crop waste soil. The isolate that gave the highest pectinase productivity was no. 7, which gave 22.03 U/ml. The isolate that gave the lowest was no. 9 (20.74 U/ml). Isolate no. 7 was named Pichia barkeri Y1 (90.91% similarity), with Gene Bank accession number OM392066.