Biology subjects

Lapanje, A.

Publications and source records attributed to Lapanje, A..

4 recordsLinked to original sources

bioRxiv2021

Strain-dependent selective antimicrobial action of cationic polyelectrolytes on Gram-negative bacteria

Although electrostatic modification of bacterial surfaces using polyelectrolytes (PEs) is a convenient and versatile tool for biotechnological processes, the ambiguities in toxicity of PEs between various bacteria and the insufficient understanding of the mechanism of action of cationic PEs and their nano-thick shells formed around the bacteria create a bottleneck of the approach. Here, we show how the viability of two bacterial strains, Escherichia coli and Pseudomonas stutzeri, both from the Gram-negative group differs, when the cells are exposed to cationic PEs under different conditions. Although the cell wall architecture of the strains should be structurally similar, we found that the viability of E. coli was not affected by the electrostatic deposition of polyethyleneimine (PEI) or poly(allylamine) hydrochloride (PAH), whereas for P. stutzeri the deposition resulted in high death rates. The cells of E. coli proved to be suitable templates for Layer-by-Layer (LbL) modification, while in P. stutzeri a modified protocol with mild conditions had to be used to ensure the viability of the cells. Super resolution stimulated emission depletion (STED) microscopy allowed us to clearly visualize that after PE deposition onto the surface of the cells, the PEs could penetrate inside the cells of P. stutzeri, while forming a capsule around E. coli as expected. Therefore, this knowledge will help us select the most appropriate combinations of strains and PEs, for biotechnological processes or biomedical application, preventing unwanted toxicity.

microbiology↗

bioRxiv2021

In vivo capture of bacterial cells by remote guiding

Recently, it has been shown that several bacterial strains can be very efficient in cancer treatment since they possess many important properties such as self-targeting, ease of detection, sensing and toxicity against tumors. However, there are only a few relevant "candidates" for such an approach, as targeting and detection one of the biggest challenges as well as there are many limitations in the use of genetic approaches. Here, it is proposed the solution that enables surface modification of alive bacterial cells without interfering with their genetic material and potentially reduces their toxic side effect. By the electrostatic interaction fluorescently labeled polyelectrolytes (PEs) and magnetite nanoparticles (NPs) were deposited on the bacterial cell surface to control the cell growth, distribution and detection of bacteria. According to the results obtained in vivo, by the magnet entrapment of the modified bacteria the local concentration of the cells was increased more than 5 times, keeping the high concentrations even when the magnet is removed. Since the PEs create a strong barrier, in vitro it was shown that the division time of the cells can be regulated for better immune presentation.

microbiology↗

bioRxiv2020

Isolation, identification and selection of bacteria with the proof-of-concept for bioaugmentation of whitewater from woodfree paper mills

When whitewater circuits in the paper industry are closed, organic compounds accumulate and cause adverse production problems, such as the formation of slime and pitch. Since wood-free whitewater is usually a mixture of additives for paper production and an efficient cost-effective purification technology for their removal is lacking, the aim of our study was to find an effective bio-based strategy for whitewater treatment using a selection of indigenous bacterial isolates. We first obtained a large collection of bacterial isolates and then tested them individually for their ability to degrade the organic additives used in papermaking, i.e. carbohydrates, resin acids, alkyl ketene dimers, polyvinyl alcohol, latex, and azo and fluorescent dyes. Out of the 355 bacterial isolates, we selected a combination of four strains (Xanthomonadales bacterium sp. CST37-CF, Sphingomonas sp. BLA14-CF, Cellulosimicrobium sp. AKD4-BF and Aeromonas sp. RES19-BTP), which cover the entire spectrum of the tested organic additives. A proof-of-concept study in pilot scale was then performed by immobilizing the cells of our artificial bacterial consortium in a 33-liter tubular flow-through reactor with a retention time of <15 h. The combination of the four native strains enabled an 88% reduction in COD of whitewater even after 21 days. Additionally, we show that the bio-based whitewater treatment surpasses photolysis and photocatalysis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=77 SRC="FIGDIR/small/398669v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@9dd48eorg.highwire.dtl.DTLVardef@1edd8cdorg.highwire.dtl.DTLVardef@347eccorg.highwire.dtl.DTLVardef@708b63_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIA strategy for selecting a consortium of indigenous bacteria with a high potential for bioaugmentation of wood-free whitewater is presented. C_LIO_LIStudy of bacterial degradation of eight chemically diverse substances used in paper production is presented. Methods for the selection of bacteria suitable for industrial application were developed. C_LIO_LIThe constructed artificial bacterial consortium consisted of strains belonging to genera Xanthomonadales bacterium, Sphingomonas, Aeromonas and Cellulosimicrobium. C_LIO_LIThe proof of concept of the industrial application, consisting of a 33-L-column filled with the immobilized artificial consortium, was an 88% decrease in COD of the whitewater effluent. C_LI

bioengineering↗

bioRxiv2020

Microbial competition reduces interaction distances to the low {micro}m-range

Metabolic interactions between cells affect microbial community compositions and hence their function in ecosystems. It is well-known that under competition for the exchanged metabolite, concentration gradients constrain the distances over which interactions can occur. However, interaction distances are typically quantified in two-dimensional systems or without accounting for competition or other metabolite-removal, conditions which may not very often match natural ecosystems. We here analyze the impact of cell-to-cell distance on unidirectional cross-feeding in a three-dimensional system with competition for the exchanged metabolite. Effective interaction distances were computed with a reaction-diffusion model and experimentally verified by growing a synthetic consortium of 1 {micro}m-sized metabolite producer, receiver and competitor cells in different spatial structures. We show that receivers cannot interact with producers [~]15 {micro}m away from them, as product concentration gradients flatten close to producer cells. We developed an aggregation protocol and created variants of the receiver cells import system, to show that within producer-receiver aggregates even low affinity receiver cells could interact with producers. These results show that competition or other metabolite-removal of a public good in a three-dimensional system reduces the interaction distance to the low micrometer-range, highlighting the importance of concentration gradients as physical constraint for cellular interactions.

microbiology↗