State-of-the-art methods for quantifying microbial polyhydroxyalkanoates

Abstract

Polyhydroxyalkanoates are a diverse class of microbially synthesized polymers that are used to make bioplastics with a wide range of applications. As interest in polyhydroxyalkanoates (PHAs) grows, researchers are faced with a challenge: how best to use the resources at their disposal to reliably quantify PHA produced by their microbe(s) of choice. Investigators must weigh the pros and cons of each method against logistical constraints (e.g., time, money, and equipment) and technical concerns (e.g., accuracy and sensitivity). At the same time, the broader community of scientists researching PHAs should aspire to land on a set of best practices. To this end, we must continually audit our methods. Here, we offer readers a snapshot of popular and emerging approaches for quantifying PHA in the lab. For each method, we provide an overview, list the primary equipment, briefly describe the methods, including improvements or iterations, and discuss the pros and cons of the approach. Along the way, we highlight gaps in research and make recommendations about best practices and future directions.

Fig 1

Overview of popular and emerging methods for quantifying microbial polyhydroxyalkanoates discussed in this minireview. The most common and most recently applied methods that provide quantitative information on intracellular PHA content fall into two categories: chromatographic methods and spectroscopic methods. Each method comes with pros and cons, summarized by the check marks and X marks, respectively. On the right, we highlight some questions that researchers should ask themselves when considering methods for quantifying PHA. On-line processes are integrated into a benchtop workflow for real-time processing, dynamic adjustment of parameters in response to changing system properties, and without requiring separate sample collection or processing steps; off-line methods involve multi-step sample collection and processing.