Pandya Trupti Hajoori Murtaza Bhagwan Mahavir Centre for Advanced Research, Bhagwan Mahavir University, Surat, Gujarat, India Bhagwan Mahavir College of Basic and Applied Sciences, Bhagwan Mahavir University, Surat, Gujarat, India Network Biology ISSN 2220-8879 http://www.iaees.org/publications/journals/nb/online-version.asp 2026 16 1 1 14 International Academy of Ecology and Environmental Sciences Hong Kong 16 June 2025 30 July 2025 1 March 2026 PHA bioplastic biodegradable Bacillus subtilis RSM modeling Polyhydroxyalkanoates (PHAs) are storage materials, accumulated by various bacteria as energy and carbon reserve materials. They are biodegradable and biocompatible; hence, they can be used in packaging and carrier molecules in the agricultural field. In the present study, we aim to produce PHA by isolating and screening PHA-accumulating bacteria by performing primary and secondary screening with Sudan Black B dye and Nile Blue A, respectively. Out of 110 isolates, 19 isolates showed bluish black colouration. The quantification of PHA was carried out by cell dry weight, and biofilm was obtained by the sodium hypochlorite-chloroform method. The isolate K2(2) showed maximum PHA production and was optimised for PHA production using the software RSM. The isolate was further classified up to the genus level by studying its morphological and biochemical characteristics, as well as 16s rRNA sequencing, and it was found to be Bacillus subtilis. The extracted PHA polymer was characterised by Fourier Transform Infrared (FTIR) spectroscopy. The isolate was tested on various parameters to check its effect on PHA production. The isolates were good candidates for the industrial production of PHA. http://www.iaees.org/publications/journals/nb/articles/2026-16(1)/production-and-optimisation-of-Polyhydroxyalkanoates.pdf