Polyhydroxybutyrate production in Bacillus mycoides DFC1 using response surface optimization for physico-chemical process parameters

Abstract

The production of polyhydroxybutyrate (PHB) by Bacillus sp. is most often growth associated and is influenced by various physico-chemical parameters. Imbalanced nutrient conditions were often found to result in sporulation and low PHB production in Bacillus sp. In the present investigation, Bacillus mycoides DFC1 strain isolated from garden soil was studied for PHB production in glucose–peptone broth. The effect of glucose/peptone ratio on biomass yield, PHB production and sporulation was investigated. Central composite rotatable design was used to study the interactive effects of three variables: glucose, peptone and pH on cell growth and PHB production. The optimized medium conditions with the constraint ‘to maximize’ cell growth and PHB content were glucose 17.34 g/l, peptone 7.03 g/l at pH 7.3. A maximum dry cell weight of 4.35 g/l and PHB yield of 3.32 g/l amounting to 76.32 % (w/w) of dry cell weight with negligible sporulation at the end of 72 h resulted in a significant increase (1.83–3.32 g/l or 1.82-fold) in the production of PHB in comparison to the medium used in preliminary studies.

Strategies for Large-scale Production of Polyhydroxyalkanoates

“…As can be seen from Table 1, poly-3-hydroxybutyrate (P(3HB) remains the most widely investigated PHA by batch fermentation, accounting for one-third of the literature reports. However, quite interestingly, there have been only few reports on the utilization of pure or refined substrates (sugars) for P(3HB) production, [27][28][29][30] while different types of inexpensive carbon sources such as agro-industrial wastes including cane molasses, sugar beet juice, rice straw hydrolysate, grass biomass hydrolysate, plant oils e.g., coconut oil, have been largely investigated. [31][32][33][34][35][36][37][38] Alcaligenes and Bacillus sp.…”

Production and Characterization of Polyhydroxyalkanoates and Native Microorganisms Synthesized from Fatty Waste

“…It clear that seeking a profitable production on an industrial scale depends on several factors such as the ability of the microorganism to employ a source of inexpensive carbon (recently, attention has focused on farm wastes and industrial byproducts), cost of the means of culture, growth rate, polymer synthesis speed, quality and quantity of PHA, and the cost of subsequent processes for the production of plastic [2,9]. Furthermore, huge efforts are focused on finding renewable and inexpensive raw materials [10,11], in the evaluation of genetically modified organisms [12], in the use of microbial consortia [13,14] to reach improvements in the process of extraction and purification [15][16][17], in the development of technologies in transgenic plants [18,19], and in the variation in strategies fermentation process (i.e., batch, fed batch, and continuous) [20][21][22].…”

Application of weighted response surface methodology for enhanced poly (3-hydroxybutyrate) production by endophytic bacillus cereus RCL 02

“…Such high amount of intracellular biopolyester accumulation with increasing concentration of complex nitrogen source like yeast extract corroborated well with the previous findings of Page 16 where, complex nitrogen sources such as fish peptone, protease peptone, yeast extract, casitone, phytone and tryptone were found to enhance the P(3HB) production in Azotobacter vinelandii UWD. Similarly, influence of glucose, peptone and pH on growth as well as P(3HB) production by B. mycoides DFC1 has been reported by Aarthi et al 17 Different statistical approaches have been used to optimize P(3HB) production from wide variety of bacteria. Plackett-Burman designed experiments showed that inoculum concentration, incubation time and xylose concentration had a positive effect, and inoculum age and incubation temperature had a negative impact on P(3HB) production from acid pre-treated rice straw hydrolysate by B. firmus NII 0830.…”