“Omics” represent a combinatorial approach to high-throughput analysis of biological entities for various purposes. It broadly encompasses genomics, transcriptomics, proteomics, lipidomics, and metabolomics. Bacteria and microalgae exhibit a wide range of genetic, biochemical and concomitantly, physiological variations owing to their exposure to biotic and abiotic dynamics in their ecosystem conditions. Consequently, optimal conditions for adequate growth and production of useful bacterial or microalgal metabolites are critically unpredictable. Traditional methods employ microbe isolation and ‘blind’-culture optimization with numerous chemical analyses making the bioprospecting process laborious, strenuous, and costly. Advances in the next generation sequencing (NGS) technologies have offered a platform for the pan-genomic analysis of microbes from community and strain downstream to the gene level. Changing conditions in nature or laboratory accompany epigenetic modulation, variation in gene expression, and subsequent biochemical profiles defining an organism’s inherent metabolic repertoire. Proteome and metabolome analysis could further our understanding of the molecular and biochemical attributes of the microbes under research. This review provides an overview of recent studies that have employed omics as a robust, broad-spectrum approach for screening bacteria and microalgae to exploit their potential as sources of drug leads by focusing on their genomes, secondary metabolite biosynthetic pathway genes, transcriptomes, and metabolomes. We also highlight how recent studies have combined molecular biology with analytical chemistry methods, which further underscore the need for advances in bioinformatics and chemoinformatics as vital instruments in the discovery of novel bacterial and microalgal strains as well as new drug leads.

Sepsis and multidrug resistance comprise a complex of factors attributable to mortality among intensive care unit (ICU) patients globally. Pathogens implicated in sepsis are diverse, and their virulence and drug resistance remain elusive. From a tertiary care hospital ICU in Uganda, we isolated a Citrobacter freundii strain RSM030 from a patient with sepsis and phenotypically tested it against a panel of 16 antibiotics including imipenem levofloxacin, cotrimoxazole and colistin, among others. We sequenced the organism's genome and integrated multilocus sequencing (MLST), PathogenFinder with Virulence Factor analyzer (VFanalyzer) to establish its pathogenic relevance. Thereafter, we combined antiSMASH and PRISM genome mining with molecular docking to predict biosynthetic gene clusters (BGCs), pathways, toxin structures and their potential targets in-silico. Finally, we coupled ResFinder with comprehensive antibiotic resistance database (CARD) to scrutinize the genomic antimicrobial resistance profile of the isolate. From PathogenFinder and MLST, this organism was confirmed to be a human pathogen (p = 0.843), sequence type (ST)150, whose virulence is determined by chromosomal type III secretion system (T3SS) (the injectosome) and plasmid-encoded type IV secretion system (T4SS), the enterobactin biosynthetic gene cluster and biofilm formation through the pgaABCD operon. Pathway and molecular docking analyses revealed that the shikimate pathway can generate a toxin targeting multiple host proteins including spectrin, detector of cytokinesis protein 2 (Dock2) and plasmalemma vesicle-associated protein (PLVAP), potentially distorting the host cell integrity. From phenotypic antibiotic testing, we found indeterminate results for amoxicillin/clavulanate and levofloxacin, with resistance to cotrimoxazole and colistin. Detailed genome analysis revealed chromosomal beta lactam resistance genes, i.e. blaCMY-79, blaCMY-116 and blaTEM-1B, along with multiple mutations of the lipopolysaccharide modifying operon genes PmrA/PmrB, pmrD, mgrA/mgrB and PhoP/PhoQ, conferring colistin resistance. From these findings, we infer that Citrobacter freundii strain RSM030 is implicated in sepsis and resistance to standard antibiotics, including colistin, the last resort.

Priestia is a genus of biotechnologically important bacteria adapted to thrive in a wide range of environmental conditions including the marine sediments. Here, we screened and isolated a strain from the Bagamoyo marine mangrove-inhabited sediments and then employed whole genome sequencing to recover and define its full genome. De novo-assembly with Unicycler (v. 0.4.8) and annotation with Prokaryotic Genome Annotation Pipeline (PGAP) revealed that that its genome contains one chromosome (5,549,131 bp), with a GC content of 37.62%. Further analysis showed that the genome contains 5,687 coding sequences (CDS), 4 rRNAs, 84 tRNAs, 12 ncRNAs, and at least 2 plasmids (1,142 bp and 6,490 bp). On the other hand, antiSMASH-based secondary metabolite analysis revealed that the novel strain (MARUCO02) contains gene clusters for biosynthesis of MEP-DOXP-dependent versatile isoprenoids (eg. carotenoids), siderophores (synechobactin and schizokinen) and polyhydroxyalkanoates (PHA). The genome dataset also informs about the presence genes encoding enzymes required for generation of hopanoids, compounds that confer adaption to harsh environmental conditions including industrial cultivation recipes. Our data from this novel Priestia megaterium strain MARUCO02 can be used for reference and in genome-guided selection of strains for production of isoprenoids as well as industrially useful siderophores and polymers, amenable for biosynthetic manipulations in a biotechnological process.

Pediatric meningitis is a global health problem, with insufficiently known pathogens and antibiotic resistance (AMR) especially in low-resource settings. Here, we sought to uncover the virulence and AMR of pathogens associated with infant meningitis, treated with ceftriaxone, in Kampala, Uganda. In a bid to isolate Klebsiella oxytoca, we coincidentally recovered a co-culture and challenged it with antibiotic susceptibility testing (AST) on a panel of 14 antibiotics. We then combined metagenome binning with antiSMASH/PRISM genome mining to unveil the pathogens, their virulence and molecular targets in relation to meningitis. From AST, the co-culture exhibited resistance to multiple aminoglycosides, fluroquinolones, and β-lactams, including ceftriaxone, the inherently used drug. From metagenome annotation, the first bin was identified as Pseudomonas aeruginosa ST242 and the second as Klebsiella michiganensis ST∗1b23. Among others, P. aeruginosa ST242 virulence factors include type 3 and type 6 secretion systems, biofilm, and nonribosomal peptides (NRPs) of the pyoverdine synthase operon, targeting claudin-5, a component of the tight junctions of the blood-brain barrier (BBB). The P. aeruginosa ST242 genome portrays intrinsic resistance to beta-lactamases (blaOXA-50 and blaPAO), aminoglycosides [aph(3′)-IIb)], fluoroquinolones (crpP), tetracycline (tmexD2) and fosfomycin (fosA), among others. From K. michiganensis ST∗1b23 genome mining we elucidated a yersiniabactin-related metabolite, targeting the ligand-binding domain of the human polymeric immunoglobulin receptor (pIgR) and other components of the BBB. The K. michiganensis ST∗1b23 chromosome encodes the genes blaOXY-1 and OqxA/B, conferring resistance to β-lactams, fluoroquinolones, and trimethoprim respectively. Notably, we found one frameshift and nine substitution mutations conferring carbapenem and cephalosporin resistance mechanisms. Overall, our findings strongly suggest coinfection and a mechanistic crosstalk between P. aeruginosa ST242 and K. michiganensis ST∗1b23 in the pathogenesis of meningitis in this case. Importantly, ceftriaxone could be an inappropriate treatment choice for these pathogens. Hence, serious surveillance and experimental studies will improve the management of pediatric meningitis.

The Klebsiella oxytoca complex comprises diverse opportunistic bacterial pathogens associated with hospital and community-acquired infections with growing alarming antimicrobial resistance. We aimed to uncover the genomic features underlying the virulence and antimicrobial resistance of isolates from Mulago National Hospital in Uganda. We coupled whole genome sequencing with Pathogenwatch multilocus sequence typing (MLST) and downstream bioinformatic analysis to delineate sequence types (STs) capsular polysaccharide K- and O-antigen loci, along with antimicrobial resistance (AMR) profiles of eight clinical isolates from the National Referral Hospital of Uganda. Our findings revealed that only two isolates (RSM6774 and RSM7756) possess a known capsular polysaccharide K-locus (KL74). The rest carry various unknown K-loci (KL115, KL128, KLI52, KL161 and KLI63). We also found that two isolates possess unknown loci for the lipopolysaccharide O-antigen (O1/O2v1 type OL104 and unknown O1). The rest possess known O1 and O3 serotypes. From MLST, we found four novel sequence types (STs), carrying novel alleles for the housekeeping genes glyceraldehyde-6-phosphate dehydrogenase A (gapA), glucose-6-phosphate isomerase (pgi), and RNA polymerase subunit beta (rpoB). Our AMR analysis revealed that all the isolates are resistant to ampicillin and ceftriaxone, with varied resistance to other antibiotics, but all carry genes for extended-spectrum beta-lactamases (ESBLs). Notably, one strain (RSM7756) possesses outstanding chromosomal and plasmid-encoded AMR to beta-lactams, cephalosporins, fluoroquinolones and methoprims. Conclusively, clinical samples from Mulago National Referral Hospital harbor novel STs and multidrug resistant K. oxytoca strains, with significant public health importance, which could have been underrated.