Techniques for tracing PHA-producing organisms and for qualitative and quantitative analysis of intra- and extracellular PHA

Poly(hydroxyalkanoates) (PHAs) constitute a versatile family of prokaryotic reserve materials that, thanks to their plastic-like properties, displays high potential for application in various fields of the plastic market. Various methods are reported for tracing PHA-producing organisms, and for qualitative and quantitative analysis of both intra- and extracellular PHA. Different techniques are needed first to discover novel powerful PHA-producing microbes, second to identify new PHA-building blocks, and thirdly for structural and conformational PHA analysis on the intramolecular level. Further, as the aspect of utmost industrial significance, methods for fast, reliable, and routine process control during PHA bioproduction are required. This review tracks the development of different methods for PHA detection and determination, such as gravimetry, turbidimetry, optical, fluorescence, or electron microscopic techniques, UV, Raman, and infrared spectrometry, genetic methods (Southern blot hybridization, PCR, fluorescence-labeled in situ hybridization), enzyme-based biosensors, H-1 and C-13 NMR, and advanced gas and liquid chromatographic approaches. We propose the most suitable techniques for particular challenges of PHA research and production, and critically assess their strengths and limitations. Moreover, we provide suggestions for future developments in order to accelerate the final launch of PHA on the bioplastic market as anticipated since decades by the respective scientific community.