Abstract
Molecular techniques for the detection of organisms, such as algae species in aquatic environments, have become the most attractive tools for typical laboratory approaches. These techniques provide more accurate and faster ways of identifying species compared to conventional methods based on microscopic counting and culture tools. The techniques of molecular biology are mostly used when numerous algal species that are present in very low amounts require identification. These tools use either entire cells or nucleic acid cell-free formats. For the entire cells, several molecular methods could be used, for example, fluorescence in situ hybridization (FISH) and microscope-based enumeration assays. For the nucleic acid cell free formats, the most commonly used tools are the sandwich hybridization assay (SHA), biosensors, quantitative PCR, real-time PCR, and microarrays. These techniques can be used individually or in combination with one or more functional laboratory tools, such as lab-on-a-chip (namely, a single incorporated system) or next-generation sequencing (NGS) to create a much higher data output. Moreover, this review integrates additional methods that promote the performance of molecular techniques. These approaches provide a high capability for identifying algal species, such as platforms and nano-bioengineered probes, magnetic systems for separation molecules, and solid-phase hybridization. Additionally, hybridization PCR and isothermal amplification tools can improve the hybridization of probes with DNA to enhance the amplification of nucleic acids. Lastly, this review discusses a field case study considered as one of the few examples of monitoring harmful algal blooms (HABs) and closes the discussion with concluding remarks and future directions.