Assessment of arsenic sorption properties of lactic acid bacteria isolated from fecal samples for application as bioremediation tool

Arsenic intoxication through contaminated water and food is a challenging problem worldwide. The objective of the present study was to isolate the As-resistant lactic acid bacteria (LAB) and assess the As sorption stoichiometry of LAB to validate its practical application as a bioremediation tool. The present study isolated 50 As-resistant LAB colonies from human (HS1-25) and albino mice (MM1-25) fecal samples. Out of 50 As-resistant LAB, the HS12 isolate exhibited the highest As removal efficiency (0.021 mg/h/g). The As bioremediation kinetic study determined the contact time 10 min and the pH between 5 and 7 for optimum As biosorption from the water. The Langmuir isotherm model (R-2 = 0.993) was well fitted with the data than the Freundlich isotherm model (R-2 = 0.876). The As bioaccumulation and scanning electron microscopy studies proved that binding of As onto cell membrane (0.000037 mg/g) and within the cell (0.000036 mg/g) are the mechanism of As sequestration of LAB HS12. The biosorption of As (2.28-20.37%) from fruit juice, soft drink and coffee as well as multimetals (0.025-0.179 mg/l; 16.22-98.69%) along with As (0.00024 mg/l) from water validated the practical application potential of HS12. The phylogenetic analysis of 16S rDNA amplicon (500 bp) of isolated potential HS12 LAB strains showed 97% similarity to Lactobacillus reuteri. Due to having As biosorption efficiency from water and liquid foods, it can be concluded that the human origin identified L. reuteri HS12 strain could be employed as a novel candidate of As bioremediation to safe environmental and human health.

Automated summary

The study isolated arsenic-resistant lactic acid bacteria with high arsenic removal efficiency, particularly the HS12 strain. It was found that this strain could effectively remove arsenic from water and liquid foods, demonstrating its potential for practical application in bioremediation.