PHB production in azomonas, acinteobacter and bacillus species: Isolation, screening and identification

Abstract

Background: Biopolymers (polyhydroxyalkanoates; PHA) are the hope for solving problems of synthetic polymers. They have a lot of applications in medicine and industry. However their production cost is still a problem. Our study aimed to solve part of the problems of PHA production. First we chose polyhydroxybutyrate (PHB) as an abundant and very well characterized member in PHA family. Then isolating easy growing bacterial isolates from soil capable of industrial production of polyhydroxybutyrate and estimating minimum time of incubation needed for its maximum production. Materials and findings: A total of 251 bacterial isolates were recovered from various soil samples. Screening for PHA production was done by viable colony staining method using Nile red. A total of 66 isolates appeared to produce PHA. Screening for PHB was done by spectrophotometric analysis where three promising bacterial isolates were obtained. These isolates were fully identified using microscopical examination, culture characteristics, biochemical reactions and sequencing of 16S ribosomal RNA gene. They were identified as Acinteobacter baumannii isolate P39, Bacillus cereus isolate P83 and Azomonas macrocytogenes P173. The final 16S ribosomal RNA sequences of the respective isolates were assembled, analyzed and submitted into Genbank. Acinteobacter isolate P39 produced 32 % PHB per dry weight after 30 hours of incubation. After 48 hours of incubation Bacillus isolate P83 and Azomonas isolate P173 produced 13 % and 24 % PHB per dry weight, respectively. Conclusion: Since PHB production had not been extensively studied in both Acinteobacter and Azomonas, this study valorizes usage of both isolates in PHB production. Further optimization studies will be conducted in the future for maximum PHB production from these three promising isolates. Keywords: Polyhydroxybutyrate, Acinteobacter baumannii, Azomonas macrocytogenes, Bacillus cereus, biopolymers.