In this review, the history of boron’s early use in drugs, and the history of the use of boron functional groups in medicinal chemistry applications are discussed. This includes diazaborines, boronic acids, benzoxaboroles, boron clusters, and carboranes. Furthermore, critical developments from these functional groups are highlighted along with recent developments, which exemplify potential prospects. Lastly, the application of boron in the form of a prodrug, softdrug, and as a nanocarrier are discussed to showcase boron’s emergence into new and exciting fields. Overall, we emphasize the evolution of organoboron therapeutic agents as privileged structures in medicinal chemistry and outline the impact that boron has had on drug discovery and development.

A polyphasic taxonomic study was carried out on the rod-shaped, orange-pigmented strain C11^T, isolated from gold mine tailings. Sequencing of the 16S rRNA gene showed a relatedness to Brevundimonas, with a 98.4% and 98.2% similarity to Brevundimonas bacteroides and Brevundimonas variabilis, respectively. The average nucleotide identity and a digital DNA–DNA hybridization with the closest phylogenetic neighbor of strain C11^T indicate distinction at the species level, further confirmed by the differences in physiology. C_18:1 ω7c is the dominant cellular fatty acid. Its DNA G + C content is 68.3 mol %. Its predominant ubiquinone is Q-10; 1,2-Di-O-acyl-3-O-α-D-glucopyranuronosyl glycerol, phosphatidylglycerol, 1,2-di-O-acyl-3-O-α-D-glucopyranosyl glycerol, and 1,2-di-O-acyl-3-O-[D-glucopyranosyl-(1→4)-α-D-glucopyranuronosyl] glycerol are its major polar lipid constituents. This bacterium produces bacteriochlorophyll a and tolerates high concentrations of (μg/mL) the following: tellurium (>1500), selenium (1000 to >5000), and vanadium (>5000) oxyanions. The data support the inclusion of the strain C11^T into the genus Brevundimonas as a new species with the proposed name Brevundimonas aurifodinae sp. nov. (C11^T = NRRL B-65718^T; =DSM 118059^T).

Aerobic anoxygenic phototrophs (AAPs) are intrinsically paradoxical; these species use a pathway commonly found in oxygen-deprived environments called anoxygenic photosynthesis, as a supplementary energy source to their obligately aerobic respiration. At the surface, such a combination seems odd, but AAPs thrive in a plethora of environments and are phylogenetically broad, suggesting that this feature is advantageous and ecologically valuable. The range of habitats and taxonomy have been reviewed, yet the main element which unites the group, their anoxygenic photosynthesis, which is diverse in its components, has not received the deserved attention. The intricate light-capturing photosynthetic complex forms the site of photon-induced energy transfer and therefore, the core basis of the process. It has two parts: the reaction center and light harvesting complex(es). The variability in composition and overall usage of the apparatus is also reflected in the genome, specifically the photosynthetic gene cluster. In this review, what is known about the differences in structure, light wavelength absorption range, activity, and related genomic content and the insights into potential AAP evolution from anaerobic anoxygenic phototrophs will be discussed. The work provides an elegant summation of knowledge accumulated about the photosynthetic apparatus and prospects that can fill yet remaining gaps.

A pink-pigmented, ovoid-rod-shaped, Gram-negative bacterial strain ML10^T was previously isolated in a study of a meromictic lake in British Columbia, Canada. It produces bacteriochlorophyll a, which is incorporated into the reaction center and light harvesting I complexes. This alongside no anaerobic or photoautotrophic growth supports the designation of the strain as an aerobic anoxygenic phototroph. The cells produce wavy polar flagellum and accumulate clear, refractive granules, presumed to be polyhydroxyalkanoate. Sequence of the 16S rRNA gene identified close relatedness to Salinarimonas rosea (97.85%), Salinarimonas ramus (97.92%) and Saliniramus fredricksonii (94.61%). The DNA G + C content was 72.06 mol %. Differences in cellular fatty acids and some physiological tests compared to Salinarimonadaceae members, as well as average nucleotide identity and digital DNA-DNA hybridization, define the strain as a new species in Salinarimonas. Therefore, we propose that ML10^T (=NCIMB 15586^T = DSM 118510^T) be classified as the type strain of a new species in the genus with the name Salinarimonas chemoclinalis sp. nov.

A pink colored, rod-shaped, prosthecate, Gram-negative bacterial strain MS644^T was discovered in saline spring water near Lake Winnipegosis, Manitoba, Canada. It produces bacteriochlorophyll a, which is incorporated into its reaction center and light harvesting I complex. Alongside no anaerobic or photoautotrophic growth, these features support its designation as an aerobic anoxygenic phototroph (AAP). Unlike most AAP, the photosynthetic apparatus is produced in significantly greater amounts compared to carotenoids. Sequence of the 16S rRNA gene identified relatedness to Glycocaulis albus (96.19%), Glycocaulis alkaliphilus (96.12%) and Glycocaulis abyssi (96.07%). The DNA G + C content was 66.01 mol %. Differences in salt tolerance and photosynthesis capability, alongside low average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization compared to other Maricauaceae, support the designation of the strain as a representative of a new genus. Therefore, we propose that strain MS644^T (=NCIMB 15625^T = DSM 121292^T) be classified as the type species of a new genus Apolloniradiicaulis in Maricaulaceae with the name A. salifontis gen. nov., sp. nov.

Marshes are an important ecosystem, acting as a biodiversity hotspot, a carbon sink and a bioremediation site, breaking down anthropogenic waste such as antibiotics, metals and fertilizers. Due to their participation in these metabolic activities and their capability to contribute to primary productivity, the microorganisms in such habitats have become of interest to investigate. Since Proteobacteria were previously found to be abundant and the waters are well aerated and organic-rich, this study on the presence of anoxygenic phototrophic bacteria, purple non-sulfur bacteria and aerobic anoxygenic phototrophs in marshes was initiated. One sample was collected at each of the seven Manitoban sites, and anoxygenic phototrophs were cultivated and enumerated. A group of 14 strains, which represented the phylogenetic diversity of the isolates, was physiologically investigated further. Aerobic anoxygenic phototrophs and purple non-sulfur bacteria were present at each location, and they belonged to the α- and β-Proteobacteria subphyla. Some were closely related to known heavy metal reducers (Brevundimonas) and xenobiotic decomposers (Novosphingobium and Sphingomonas). All were able to synthesize the photosynthetic complexes aerobically. This research highlights the diversity of and the potential contributions that anoxygenic phototrophs make to the essential functions taking place in wetlands.