Biology subjects

Goldbeck, O.

Publications and source records attributed to Goldbeck, O..

4 recordsLinked to original sources

bioRxiv2022

Identification, Characterization and Mode of Action of Corynaridin, a Novel Linaridin from Corynebacterium lactis

Genome analysis of Corynebacterium lactis revealed a bacteriocin gene cluster encoding a putative bacteriocin of the linaridin family of ribosomally synthesized and posttranslationally modified peptides (RIPPs). The locus harbors typical linaridin modification enzymes but lacks genes for a decarboxylase and methyltransferase, which is unusual for type B linaridins. Supernatants of Corynebacterium lactis RW3-42 showed antimicrobial activity against Corynebacterium glutamicum. Deletion of the precursor gene crdA clearly linked the antimicrobial activity of the producer strain to the identified gene cluster. Following purification, we observed potent activity of the peptide against Actinobacteria, mainly other members of the genus Corynebacterium including the pathogenic species Corynebacterium striatum and Corynebacterium amycolatum. Also, low activity against some Firmicutes was observed, but no activity against Gram-negative species. The peptide is resilient towards heat but sensitive to proteolytic degradation by trypsin and proteinase K. Notably, time-kill kinetics and experiments using live biosensors to monitor membrane integrity suggest bactericidal activity that does not involve formation of pores in the cytoplasmic membrane. As Corynebacterium species are ubiquitous in nature and include important commensal and pathogens of mammalian organisms, secretion of bacteriocins by species of this genus could be a hitherto neglected trait with high relevance for intra- and interspecies competition and infection. ImportanceBacteriocins are antimicrobial peptides produced by bacteria to fend off competitors in ecological niches and are considered to be important factors influencing the composition of microbial communities. However, bacteriocin production by bacteria of the genus Corynebacterium has been a hitherto neglected trait, although its species are ubiquitous in nature and make up large parts of the microbiome of humans and animals. In this study, we describe and characterize a novel linaridin-family bacteriocin from Corynebacterium lactis and show its narrow spectrum activity, mainly against other actinobacteria. Moreover, we were able to extend the limited knowledge on linaridin bioactivity in general and for the first time describe the mode of action of such a bacteriocin. Interestingly, the peptide, which was named corynaridin, appears bactericidal, but without formation of pores in the bacterial membrane.

microbiology↗

bioRxiv2022

Improved fluorescent Listeria spp. biosensors for analysis of antimicrobials by flow cytometry

The global increase in antibiotic resistances of pathogenic microorganisms require identification and characterization of novel antimicrobials. Bacterial biosensors expressing fluorescent proteins such as pHluorin variants are suitable for high-throughput screenings. Here, we present Listeria spp. pH-sensitive biosensors with improved fluorescence for single cell analysis of antimicrobials by flow cytometry.

microbiology↗

bioRxiv2021

Towards improved resistance of Corynebacterium glutamicum against nisin

The bacteriocin nisin is one of the best studied antimicrobial peptides. It is widely used as a food preservative due to its antimicrobial activity against various Gram-positive bacteria including human pathogens such as Listeria monocytogenes and others. The receptor of nisin is the universal cell wall precursor lipid II, which is present in all bacteria. Thus, nisin has a broad spectrum of target organisms. Consequently, heterologous production of nisin with biotechnological relevant organisms including Corynebacterium glutamicum is difficult. Nevertheless, bacteria have evolved several mechanisms of resistance against nisin and other cationic antimicrobial peptides (CAMPs). Here, we transferred resistance mechanisms described in other organisms to C. glutamicum with the aim to improve nisin resistance. The presented approaches included: expression of (i) nisin immunity genes nisI and/or nisFEG or (ii) nisin ABC-transporter genes of Staphylococcus aureus and its homologues of C. glutamicum, (iii) genes coding for enzymes for alanylation or lysinylation of the cell envelope to introduce positive charges, and/or (iv) deletion of genes for porins of the outer membrane. None of the attempts alone increased resistance of C. glutamicum more than two-fold. To increase resistance of C. glutamicum to levels that will allow heterologous production of active nisin at relevant titers, further studies are needed.

microbiology↗

bioRxiv2019

Immediate inhibition of sucrose uptake in Corynebacterium glutamicum in response to intracellular glucose-6-phosphate accumulation requires the ptsG encoded EII-permease

Corynebacterium glutamicum co-metabolizes most carbon sources, such as glucose and sucrose. Uptake of those sugars by the PTS involves a glucose- and a sucrose-specific permease EIIGlc (ptsG) and EIISuc (ptsS), respectively. Block of glycolysis by deletion of pgi (encodes phosphoglucoisomerase) redirects glucose-driven carbon flux towards pentose phosphate pathway. C. glutamicum {Delta}pgi grows poorly with glucose but has unaffected, good growth with sucrose. However, addition of glucose to sucrose-cultivated C. glutamicum {Delta}pgi immediately arrested growth via inhibition of the EIISuc-mediated sucrose uptake and reduction of ptsS-mRNA amounts. Kinetic analyses revealed that sucrose uptake inhibition in C. glutamicum {Delta}pgi took place within 15 s after glucose addition. We show that inhibition of PTS-mediated sucrose uptake occurs as direct response to glucose-6-P accumulation. Moreover, addition of non-PTS substrates, which are metabolized to glucose-6-P such as maltose or glucose-6-P itself (uptake was enabled by heterologously produced UhpT), led to similar growth and sucrose uptake inhibition as glucose addition. Despite EIIGlc not being involved in uptake of these substrates, negative effects on sucrose uptake after addition of maltose and glucose-6-P were absent in the EIIGlc-deficient strain C. glutamicum {Delta}pgi{Delta}ptsG. These results show that the ptsG-encoded EIIGlc is part of a novel mechanism for perception of intracellular glucose-6-P accumulation and instantaneous inhibition of EIISuc-mediated sucrose uptake in C. glutamicum. This novel mode of control of PTS activity by an early glycolytic metabolite probably allows efficient adaptation of sugar uptake to the capacity of the central metabolism during co-metabolization, which is characteristic for C. glutamicum.\n\nIMPORTANCECoordination of substrate uptake and metabolism are a prerequisite for efficient co-utilization of substrates, a trait typical for the Gram-positive C. glutamicum. Sucrose uptake via the PTS permease EIISuc in this organism immediately was inhibited in response to intracellular accumulation of the glycolysis intermediate glucose-6-phosphate. This inhibition depends exclusively on the presence but not activity of the PTS permease EIIGluc. Thus, C. glutamicum possesses a novel, immediate, and PTS-dependent way to control and coordinate both uptake and metabolization of multiple substrates by monitoring of their metabolic levels in the cell. This offers new insights and interesting concepts for a further rational engineering of this industrially important production organism and exemplifies a putative general strategy of bacteria for the coordination of sugar uptake and central metabolism.

microbiology↗