Science Letters

Research article

Optimization and effect of Zn2+, Mn2+ and Ni2+ on poly- -hydroxybutyrate (PHB) synthesis by Bacillus subtilis ATCC 6633

Waseem Raza*1, Wang Yang2, Muhammad Faheem1, Sohail Yousaf3

1College of Resources and Environmental Sciences, Nanjing Agricultural University, 210095, Nanjing, China

2Nanjing University of Science and Technology, 210094, Nanjing, China

3Department of Environmental Sciences, Quaid-i-Azam University, Islamabad, Pakistan

Abstract

The environmental impact of non-biodegradable polymers shifted the researcher's trend towards the discovery of biodegradable polymers. Among those, poly- -hydroxybutyrate (PHB) is an attractive polymer that is produced by microorganisms. The aim of the this study was to assess the capability of Bacillus subtilis strain ATCC 6633 to accumulate PHB under different growth conditions, in addition, the role of three metal ions (Zn2+, Mn2+ and Ni2+) on the synthesis of PHB was also evaluated. The results showed that the maximum PHB accumulation by strain ATCC6633 was obtained after 48 hours of incubation at the temperature of 30oC and at pH 7, while D-mannitol as C source and glycine as N source showed maximum PHB accumulation. The results of the three metal ions effect on PHB accumulation by strain ATCC6633 revealed that the metal ion Ni2+ was most effective in increasing PHB accumulation followed by Zn2+ and then Mn2+. This research will help to enhance the understanding of the effect of optimum growth conditions and metal ions on PHB accumulation by strain ATCC6633.

Key words: Bacillus subtilis, C source, N source, optimization, poly- -hydroxybutyrate.

Received June 05, 2013; Revised August 12, 2013; Accepted August 24, 2013

*Corresponding author: Dr. Waseem Raza; Email: waseem@njau.edu.cn; Phone: +86-15161459593; Fax: +86-2584432420