The work published in the prestigious journal Current Biology, IF=8.9, for the first time describes the molecular mechanisms behind a fascinating ability of bacteria to discriminate between and respond differentially to kin and non-kin; phenomenon identified as bacterial kin discrimination. By using transposon mutagenesis, reverse genetics, transcriptomics, comparative genomics and swarming compatibility assay we showed for the first time in collaboration with Harvard that KD relays on combinatorial system involving several genetic loci. These function in 1) attack and defense, 2) synthesis of bacterial cell wall, 3) production of the major extracellular polysaccharide Eps and as 4) regulatory factors involved in stress response. The number of different attack and defense functions increases with phylogenetic distance between strains. The KD in B. subtilis is of combinatorial nature as it relies on more than one genetic determinant which are present in natural strains in different combinations and provide a dynamic system for assortment of strains based on their relatedness which are expected to have overlapping ecological niches. This KD system may therefore stabilize cooperation between kin. The paper has been already cited 6 times.
COBISS.SI-ID: 4636280
In this study, published in highly regarded scientific journal "ACS applied materials & interfaces", IF = 7,1, and was already cited 18 times, we examined bacterial adhesion on titanium-substrates used for bone implants. The affinity of the anatase coatings toward bacterial attachment was studied by using a green fluorescent protein-expressing Escherichia coli (gfp-E. coli) strain in connection with surface photoactivation by UV irradiation. In addition, we have analyzed the effects of surface topography, roughness, charge, and wettability. The results suggested the dominant effects of the macroscopic surface topography and microasperity at the surface roughness scale, which were produced during titanium machining, hydrothermal tratment, or both. In the case of TiO2-coated samples, the nanocrystals reduced the width between the microasperities adding nanoroughness features which decreased the contact area between the bacterium and the coating, with consequent lower bacterial adhesion (up to 50 % less) in comparison to the nontreated titanium. No correlation was found between the bacterial adhesion and the ζ-values of the samples in PBS.
COBISS.SI-ID: 4496504
Prodigiosin exhibits a potent antimicrobial activity against a broad range of Gram positive and Gram negative bacteria. The mechanism of its antimicrobial action, however, is not known. In the paper, the effect of prodigiosin on B. subtilis growth, cell membrane leakage, and induction of autolysins was studied. Treating B. subtilis with prodigiosin resulted in rapid decline of optical density and increased cell membrane leakage measured by β-galactosidase activity. Cell lysis was initiated immediately after treatment with prodigiosin in the middle exponential phase and was completed within two hours. Lytic activity of prodigiosin in mutant strains with impaired autolysin genes lytABCD decreased for 80 % compared to the wild-type strain, while in lytABCDEF mutant strain prodigiosin had no bacteriolytic but only bacteriostatic effect. The results of this study demonstrate that prodigiosin exhibits a potent antimicrobial activity against B. subtilis. It acts as a bacteriolytic agent during the exponential growth and as a bacteriostatic agent during the stationary growth. Prodigiosin interferes with cytoplasmic membrane function and increases its permeability. The obtained results indicate that prodigiosin´s bacteriolytic activity is due to the induction of autolysins. The paper was cited 3 times.
COBISS.SI-ID: 4619128
In order to survive in food-processing environments and cause disease, Campylobacter jejuni requires specific survival mechanisms, such as biofilms, which contribute to its transmission through the food chain to the human host and present a critical form of resistance to a wide variety of antimicrobials. Phytochemical analysis of thyme ethanolic extract (TE), thyme post-hydrodistillation residue (TE-R), and olive leaf extract (OE) using high-performance liquid chromatography with photodiode array indicates that the major compounds in TE and TE-R are flavone glucuronides and rosmarinic acid derivatives, and in OE verbascoside, luteolin 7-O-glucoside and oleuroside. We tested their antiadhesive activity to bacterial C. jejuni adhesion on abiotic polistyrene or biotic pig (PSI) and human foetal (H4) small-intestine cell lines. Our findings suggest that TE, the agro-food waste material TE-R, and the by-product OE represent sources of bioactive phytochemicals that are effective at low concentrations and can be used as therapeutic agents to prevent bacterial adhesion.
COBISS.SI-ID: 4558200
Prof. dr. Mandic-Mulec was invited as an expert on metagenomics to co-author an opinion article that brought together 46 experts from all over the world and has attracted high attention of the scientific community. It has already reached in one year the alimetric score of 27, which means that it is in the 96th percentile and thus in the top 5 % of all research outputs ever tracked by Altmetric. It has been also cited 5 times. Direct extraction and characterization of microbial community DNA through PCR amplicon surveys and metagenomics has revolutionized the study of environmental microbiology and microbial ecology. In particular, metagenomic analysis of nucleic acids provides direct access to the genomes of the “uncultivated majority.” Accelerated by advances in sequencing technology, microbiologists have discovered unprecedented number of novel phyla, classes, genera, and genes from microorganisms. The unsurpassed diversity of soils promises continued exploration of a range of industrial, agricultural, and environmental functions, bringing a promise for answering many outstanding who, what, where, when, why, and with whom questions such as: Which microorganisms are linked to which soil habitats? How do microbial abundances change with changing conditions? How do microbial assemblages interact and influence one another synergistically or antagonistically? What is the role of horizontal gene transfer in the stability of microbial communities? And more. The article brings key insights into the state of the art, challenges and promises of soil metagenomics and paves the way for the future of soil metagenomics.
COBISS.SI-ID: 4619896