Biotinylation-based lateral flow assays for pathogenic and total bacteria detection

Background: It is highly desirable to concurrently evaluate both pathogenic and total bacteria in water and food environments. As a point-of-care platform for biochemical tests, lateral flow assay (LFA) has been widely used for pathogenic bacteria due to its portability and fast time of outcome. However, traditional LFA was unable to detect total bacteria due to the lack of a universal antibody that could bind all the bacteria.

Results: Here, we used sulfo-NHS-biotin to label nonspecifically the lipoprotein of bacterial surface. Meanwhile, streptavidin was used for both AuNP modification and membrane coating to prepare Str-AuNP reporter and test line, respectively. Thus, a biotinylation-based LFA was established for total bacteria detection. The conditions for preparing biotinylated bacteria and Str-AuNP were optimized. Under the optimal condition, all the bacteria could be successfully biatinylated and further be semi quantified by using the test strips with color band. Good practicability of the as-developed LFA in detecting total bacteria from pond and wastewater was demonstrated. Combined with biotin-antibody for specific biotinylation, the as-developed FLA was also successfully used for pathogenic bacteria detection with good selectivity and without the de novo preparation of the test strips.

Significance and novelty: For the first time, the nonspecific biotinylation of bacteria was integrated into the LFA to address the inherent challenges in LFA for total bacteria detection. Taking the advantage of the universal recognition reaction between the biotin and streptavidin, we established biotinylation-based LFAs for both pathogenic and total bacteria detection without the de novo preparation of the test strips. It would have practical applications in the rapid bacterial detection for water quality management and control.