Production of the antimicrobial compound tetrabromopyrrole and the Pseudomonas quinolone system precursor, 2-heptyl-4-quinolone, by a novel marine species Pseudoalteromonas galatheae sp. nov.

Abstract

Novel antimicrobials are urgently needed due to the rapid spread of antibiotic resistant bacteria. In a genome-wide analysis of Pseudoalteromonas strains, one strain (S4498) was noticed due to its potent antibiotic activity. It did not produce the yellow antimicrobial pigment bromoalterochromide, which was produced by several related type strains with which it shared less than 95% average nucleotide identity. Also, it produced a sweet-smelling volatile not observed from other strains. Mining the genome of strain S4498 using the secondary metabolite prediction tool antiSMASH led to eight biosynthetic gene clusters with no homology to known compounds, and synteny analyses revealed that the yellow pigment bromoalterochromide was likely lost during evolution. Metabolome profiling of strain S4498 using HPLC-HRMS analyses revealed marked differences to the type strains. In particular, a series of quinolones known as pseudanes were identified and verified by NMR. The characteristic odor of the strain was linked to the pseudanes. The highly halogenated compound tetrabromopyrrole was detected as the major antibacterial component by bioassay-guided fractionation. Taken together, the polyphasic analysis demonstrates that strain S4498 belongs to a novel species within the genus Pseudoalteromonas, and we propose the name Pseudoalteromonas galatheae sp. nov. (type strain S4498T = NCIMB 15250T = LMG 31599T).

Effects of Heat Stress and Exogenous Salicylic Acid on Secondary Metabolites Biosynthesis in Pleurotus ostreatus (Jacq.) P. Kumm

“…Fortimicin is an aminoglycoside antibiotic [ 31 ]. 2-Heptyl-4-quinolone is a kind of tetrabromopyrrole, which has been shown to exhibit antibiotic activity against human and marine bacteria [ 32 ]. Protomycinolide IV and rimocidine are macrolide antibiotics [ 33 ].…”

Quorum Sensing Regulates Bacterial Processes That Play a Major Role in Marine Biogeochemical Cycles

“…The PQS system has mostly been studied in clinical Pseudomonas strains, where it regulates virulence factors (such as biofilm, elastase, rhamnolipid or pyocyanin) production and promotes infection (as reviewed in García-Reyes et al, 2020). However, the synthesis of PQS and HHQ has been discovered in other genera, such as Burkholderia and a marine Pseudoalteromonas bacterium (Vial et al, 2008;Paulsen et al, 2020). In addition, it has been shown that PQS acts as a signal molecule in several Gram-negative and Gram-positive strains (including marine isolates) (Reen et al, 2011) as well as in multispecies marine communities (Wang et al, 2020), highlighting its role as a possible interspecies signal.…”

How Do Quorum-Sensing Signals Mediate Algae–Bacteria Interactions?

“…Green algae are apparently less sensitive to AQs, as was shown by Patidar et al, who found that the inhibitory effects of AQs produced by Pelagibaca bermudensis were outweighed by other growth promoting effects when co-cultured with the green alga Tetraselmis striata [ 51 ]. Other AQs have been isolated from a variety of marine environments, including several unusual AQs from sponge-associated bacteria [ 52 , 53 , 54 ] and heptyl-quinolone from planktonic and algae-associated bacteria [ 27 , 55 , 56 ].…”