A High Throughput Isolation Method for Phosphate-Accumulating Organisms

Abstract

Hyperphosphatemia is a secondary issue associated with chronic kidney disorder. Use of phosphate binders and dialysis are the treatments for hyperphosphatemia, albeit with harmful side effects and high cost, respectively. A safer and healthier approach is attempted to administer phosphate-accumulating organisms (PAOs) from probiotics to prevent hyperphosphatemia. However, screening and isolation of PAOs are limited by inefficient enrichment of relevant metabolism and contamination. Therefore, we devised a novel strategy to isolate elite PAOs from Lactobacillus casei JCM 1134 and Bifidobacterium adolescentis JCM 1275 (previously reported PAOs). PAOs were first enriched for phosphate uptake and incubated in low-pH phosphate-free media to dormant non-PAOs, and then purified using Percoll density gradient centrifugation. Subsequently, elite PAOs were isolated from centrifuged pellet on a toluidine blue O-supplemented agar-based media. Using this technique, elite PAOs could not only be isolated, but also semi-quantitatively scored for their phosphate accumulation capabilities. Additionally, these scores correlated well with their accumulated phosphate values. The elite PAOs isolated from L. casei and B. adolescentis showed 0.81 and 0.70 [mg-phosphate/mg-dry cell], respectively (23- and 4.34-fold increase, respectively). Thus, our method can be used to successfully isolate elite PAOs, which might be of use to prevent hyperphosphatemia at early stages.