Antibacterial potential of γ-linolenic acid from Fischerella sp. colonizing Neem tree bark

Abstract

Pharmaceutically important c-linolenic acid (GLA) was produced (4.1 mg g )1 dry wt) by laboratory grown cyanobacterium Fischerella sp. colonizing Neem (Azadirachta indica) tree bark. GLA isolated from the test cyanobacterium was active against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25992, Salmonella typhi (local strain), Pseudomonas aeruginosa ATCC 27853 and Enterobacter aerogenes MTCC 2822. The overproduction of GLA was also monitored by altering phosphate and nitrate levels in the nutrient medium. A doubling in phosphate concentration (58 lM) increased GLA level up to 12% over that of control cells while half of this phosphate level reduced GLA synthesis by 8%. In contrast, elevated nitrate concentrations (5 and 10 mM) stimulated biomass yield but not GLA, as the levels approximated to the nitrate-lacking control. The antibacterial potential of GLA from Fischerella sp. grown at varying P or N levels was at variance as evidenced by the diameter of inhibition zones against S. aureus. This variation in inhibition zones reflected differing levels of GLA as ascertained quantitatively by HPLC.

Antibacterial Activity of Long-Chain Polyunsaturated Fatty Acids against Propionibacterium acnes and Staphylococcus aureus

“…The LC-PUFAs killed S. aureus rapidly with kill times similar to earlier observations for other fatty acids against this bacterium, including caprylic acid (C8:0) [33], lauric acid [34], sapienic acid (C16:1 n -10) [35,36], oleic acid (C18:1 n -9) [37], GLA [19] and EPA [38]. Such rapid cell death caused by the LC-PUFAs strongly suggests a cell membrane lytic mechanism of action against S. aureus , which is in line with previous studies on Gram-positive species (see review by Desbois and Smith [9]).…”

Baltic cyanobacteria – a source of biologically active compounds

“…Although many tests have been performed, and strong antimicrobial activities were revealed in numerous cyanobacterial strains, few structures responsible for these activities have been identified. The compounds have mainly been classified to alkaloids, fatty acids, peptides, lipopeptides and terpenoids (Asthana et al, 2006;Silva-Stenico et al, 2010;Chlipala et al 2011;Guedes et al, 2011;Nagarajan et al, 2012). In our studies, more than half of the pathogenic strains were sensitive to the extracts from the Baltic cyanobacteria.…”

Genome mining for natural product biosynthetic gene clusters in the Subsection V cyanobacteria

“…In particular, the Subsection V cyanobacteria are well known for the production of the hapalindole-family of compounds, a group of structurally related indole alkaloids consisting of hapalindoles, welwitindolinones and fisherindoles which display a broad range of bioactivities [ 5 , 6 ]. Other metabolites isolated from Subsection V cyanobacteria include the hepatotoxin microcystin [ 7 – 9 ], the cyclic peptide, hapalosin [ 10 , 11 ], hydrocarbons [ 12 ], fischerellin A and B [ 13 – 15 ], the cyclic peptide westiellamide [ 16 ], the aromatic compounds ambigol A, B, C and 2,4-dichlorobenzoic acid [ 17 , 18 ], the alkaloid tjipanazole D [ 18 ], the depsipeptide stigonemapeptin [ 19 ], the hexapeptide hapalocyclamide [ 20 ], the antimicrobial compound parsiguine [ 21 ], and the long chain polyunsaturated fatty acid γ-Linolenic acid [ 22 ].…”