Non-selective Separation of Bacterial Cells with Magnetic Nanoparticles Facilitated by Varying Surface Charge

Abstract

Recovering microorganisms from environmental samples is a crucial primary step for understanding microbial communities using molecular ecological approaches. It is often challenging to harvest microorganisms both efficiently and unselectively, guaranteeing a similar microbial composition between original and separated biomasses. A magnetic nanoparticles (MNPs) based method was developed to effectively separate microbial biomass from glass fiber pulp entrapped bacteria. Buffering pH and nanoparticle silica encapsulation significantly affected both biomass recovery and microbial selectivity. Under optimized conditions (using citric acid coated Fe3O4, buffering pH = 2.2), the method was applied in the pretreatment of total suspended particle sampler collected bioaerosols, the effective volume for DNA extraction was increased 10-folds, and the overall method detection limit of microbial contaminants in bioaerosols significantly decreased. A consistent recovery of the majority of airborne bacterial populations was demonstrated by in-depth comparison of microbial composition using 16S rRNA gene high-throughput sequencing. Surface charge was shown as the deciding factor for the interaction between MNPs and microorganisms, which helps developing materials with high microbial selectivity. To our knowledge, this study is the first report using MNPs to separate diverse microbial community unselectively from a complex environmental matrix. The technique is convenient and sensitive, as well as feasible to apply in monitoring of microbial transport and other related fields.

pH-Induced Modulation of Vibrio fischeri Population Life Cycle

“…In addition to being an important parameter subject to variations in natural environments, e.g., during ecotoxicity testing, particularly of responsive nanomaterials, pH represents a factor that can be systematically controlled in model experiments that elucidate the long-term environmental effects on both physicochemical and biological characteristics of V. fischeri. The emerging interest in using model V. fischeri populations in long-term bioassays, including under the environmental exposure to anthropogenic nanoparticles [40,41] that interact with microorganisms via both physicochemical and biological pathways [42][43][44][45][46][47], further highlights the practical importance of understanding the pH-dependent life cycle of V. fischeri populations. Accordingly, we used multiple complementary physicochemical and biological techniques to quantitatively follow the pH-dependent life cycles of V. fischeri populations via a combination of continuous and discrete timepoint measurements.…”

Effects of different quantities of antibody conjugated with magnetic nanoparticles on cell separation efficiency

“…MNPs have shown promise in biotechnology due to their low toxicity, superparamagnetism, high surface area and simple separation [9,10,11,12]. While, the high viscosity and large sizes of microbeads prevented their efficient interaction with cell surfaces, the higher surface area rather than microparticles and an efficient nano sizes of nanoparticles facilitate the bioseparation and purification of a variety of biomacromolecules and cells [13] including proteins [14], nucleic acids [15], viruses [16], bacteria [17,18], and cancerous cells [19]. They have also been applied for drug delivery [20,21], magnetic resonance imaging [22,23,24,25], hyperthermia [26], diagnosis and treatment in various cancers [27,28,29,30], and magnetic separation [31,32].…”

Selective, Agglomerate-Free Separation of Bacteria Using Biofunctionalized, Magnetic Janus Nanoparticles

“…Consequently, the development of magnetic-nanoparticle-based systems with a highly improved bacterial capture, separation, and elimination efficiency is desired. To this end, various surface functionalizations of magnetic particles have been reported in recent publications, e.g., bacteria-specific antibodies, ,, amino acids, , aminated silanes, − drugs, surfactants, or synthetic ligands, which have an improved capture efficiency to some extent.…”