SQ 28,332, a new monobactam produced by a Flexibacter sp. Taxonomy, fermentation, isolation, structure determination and biological properties

Genomic and Chemical Decryption of the Bacteroidetes Phylum for Its Potential to Biosynthesize Natural Products

With progress in genome sequencing and data sharing, 1,000s of bacterial genomes are publicly available. Genome mining-using bioinformatics tools in terms of biosynthetic gene cluster (BGC) identification, analysis, and rating-has become a key technology to explore the capabilities for natural product (NP) biosynthesis. Comprehensively, analyzing the genetic potential of the phylum Bacteroidetes revealed Chitinophaga as the most talented genus in terms of BGC abundance and diversity. Guided by the computational predictions, we conducted a metabolomics and bioactivity driven NP discovery program on 25 Chitinophaga strains. High numbers of strain-specific metabolite buckets confirmed the upfront predicted biosynthetic potential and revealed a tremendous uncharted chemical space. Mining this data set, we isolated the new iron chelating nonribosomally synthesized cyclic tetradeca- and pentadecalipodepsipeptide antibiotics chitinopeptins with activity against Candida, produced by C. eiseniae DSM 22224 and C. flava KCTC 62435, respectively. IMPORTANCE The development of pipelines for anti-infectives to be applied in plant, animal, and human health management are dried up. However, the resistance development against compounds in use calls for new lead structures. To fill this gap and to enhance the probability of success for the discovery of new bioactive natural products, microbial taxa currently underinvestigated must be mined. This study investigates the potential within the bacterial phylum Bacteroidetes. A combination of omics-technologies revealed taxonomical hot spots for specialized metabolites. Genome- and metabolome-based analyses showed that the phylum covers a new chemical space compared with classic natural product producers. Members of the Bacteroidetes may thus present a promising bioresource for future screening and isolation campaigns.

Bioactive natural products from Bacteroidetes

Covering: up to end of January 2022Bacteria representing the phylum Bacteroidetes produce a diverse range of natural products, including polyketides, peptides and lactams. Here, we discuss unique aspects of the bioactive compounds discovered thus far, and the corresponding biosynthetic pathways if known, providing a comprehensive overview of the Bacteroidetes as a natural product reservoir.

Targeting the Achilles' Heel of Bacteria: Different Mechanisms To Break Down the Peptidoglycan Cell Wall during Bacterial Warfare

Bacteria commonly live in dense polymicrobial communities and compete for scarce resources. Consequently, they employ a diverse array of mechanisms to harm, inhibit, and kill their competitors. The cell wall is essential for bacterial survival by providing mechanical strength to resist osmotic stress. Because peptidoglycan is the major component of the cell wall and its synthesis is a complex multistep pathway that requires the coordinate action of several enzymes, it provides a target for rival bacteria, which have developed a large arsenal of antibacterial molecules to attack the peptidoglycan of competitors. These molecules include antibiotics, bacteriocins, and contact-dependent effectors that are either secreted into the medium or directly translocated into a target cell. In this minireview, we summarize the diversity of these molecules and highlight distinct mechanisms to disrupt the peptidoglycan, giving special attention to molecules that are known or have the potential to be used during interbacterial competitions.

Natural Products Containing a Nitrogen-Sulfur Bond

Only about 100 natural products are known to contain a nitrogen-sulfur (N-S) bond. This review thoroughly categorizes N-S bond-containing compounds by structural class. Information on biological source, biological activity, and biosynthesis is included, if known. We also review the role of N-S bond functional groups as post-translational modifications of amino acids in proteins and peptides, emphasizing their role in the metabolism of the cell.

Biologically active secondary metabolites from myxobacteria

New chemical structures with proven biological activity still are badly needed for a host of applications and are intensively screened for. Suitable compounds may be used as such, or in the form of their derivatives or, equally important, may serve as lead compounds for designing synthetic analogs. One way to new compounds is the exploitation of new producer organisms. During the past 15 years the myxobacteria have been shown in our laboratories to be a rich source of novel secondary metabolites, many of the compounds showing interesting and sometimes unique mechanisms of action. About 50 basic structures and nearly 300 structural variants have been elucidated, and almost all of them turned out to be new compounds. Several myxobacterial substances may have a good chance of an application.

Development of techniques to genetically manipulate members of the genera Cytophaga, Flavobacterium, Flexibacter, and Sporocytophaga

The Bacteroides-Cytophaga-Flavobacterium branch of the eubacterial phylogenetic tree contains a diverse group of bacterial species. Techniques for the genetic manipulation of Bacteroides spp. are well developed (A. A. Salyers, N. B. Shoemaker, and E. P. Guthrie, Crit. Rev. Microbiol. 14:49-71, 1987). Recently we developed techniques to genetically manipulate the gliding bacterium Cytophaga johnsonae (M. J. McBride and M. J. Kempf, J. Bacteriol. 178:583-590, 1996). We now demonstrate that some of these techniques allow genetic manipulation of a number of environmentally or medically significant bacteria in this group. The Bacteroides transposon Tn4351 was introduced into Cytophaga hutchinsonii, Cytophaga succinicans, Flavobacterium meningosepticum, Flexibacter canadensis, Flexibacter sp. strain FS1, and Sporocytophaga myxococcoides by conjugation. Tn4351 integrated itself into the host chromosomes and conferred erythromycin resistance. We isolated several auxotrophic mutants of Flavobacterium meningosepticum following Tn4351 mutagenesis. The C. johnsonae-Escherichia coli shuttle vector pCP11 functioned in C. succinicans but not in the other bacteria. pLYL03 did not replicate in any of these bacteria and should function as a convenient suicide vector. The identification of a system of gene transfer, a selectable marker, a suicide vector, and a transposon that functions in these diverse bacteria allows genetic manipulations to be performed.