# Probiotic-infused activated charcoal/ hydroxyapatite microbeads: a novel strategy to disinfection

## TL;DR

This paper introduces a new disinfectant using probiotic-infused microbeads to rapidly kill pathogens and provide long-term protection on high-risk surfaces.

## Contribution

A novel dual-action disinfectant combining probiotics with activated charcoal/hydroxyapatite microbeads for sustained pathogen control.

## Key findings

- PIMD reduced pathogen loads by ≥99.9% within 1 hour on various surfaces.
- Probiotic viability was maintained for at least 21 days post-application.
- The formulation showed a mean inhibition zone of 13.84 mm across 43 pathogens.

## Abstract

To develop a non-toxic, probiotic-infused activated charcoal/hydroxyapatite microbeads (PIMD) formulated with activated charcoal and hydroxyapatite. The formulation is designed to establish a stable probiotic biofilm on high-risk surfaces, such as medical sink basins and food cutting boards. Its dual mechanism aims to achieve rapid pathogen inhibition and long-term protection through sustained competitive exclusion, including against antibiotic-resistant microorganisms.

An applied study was conducted in the Al-Baha region of Saudi Arabia (January 2021–May 2025) employing probiotic-based biotechnology to engineer spatially segregated microenvironments using activated charcoal–hydroxyapatite microbeads. The study integrated ecological modeling concepts—including Gause’s competitive exclusion principle, Lotka–Volterra dynamics and agent-based cross-feeding simulations—with antimicrobial sensitivity assays and surface disinfection trials. Twelve probiotic strains capable of competitively excluding pathogens and producing antimicrobial compounds were encapsulated within activated charcoal and hydroxyapatite porous microbeads. The efficacy of the novel disinfectant was evaluated on stainless steel sink basins, food-grade cutting boards, and culture plates challenged with 43 pathogenic strains.

The PIMD formulation remained physically stable under storage conditions, with probiotic viability largely preserved at –20 °C (0.46 log10 CFU/mL reduction) and 4 °C (0.89 log10 reduction) over 365 days. PIMD exhibited rapid broad-spectrum disinfection, reducing pathogen loads by ≥ 99.9% within 1 h, and maintained protective biofilm-mediated probiotic viability at ≥ 5.0 log10 CFU/cm2 for at least 21 days post-application across tested surfaces, including cutting boards, sink basins, and outdoor tiles. The mean inhibition zone diameter across 43 pathogens was 13.84 ± 1.23 mm, with a bactericidal outcome observed for 34.9% of tested strains.

PIMD represents a dual-action strategy combining rapid disinfection with sustainable microbial balance, for reducing reliance on antibiotics and chemical disinfectants while enhancing surface safety in diverse environments such as healthcare, food facilities, and beyond.