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The antimicrobial activity of new meso-tetrakis(N-methyl-6-quinolinyl)-substituted porphyrins and meso-tetrakis(N-methyl-6-quinolinyl)-substituted chlorins is described. The dark toxicity and photosensitising potentials of free-base (TQP and TQC) and its Sn(IV)-complexes [(TQP)Sn(IV) and (TQC)Sn(IV)] were tested on Gram-positive (Staphylococus aureus), Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and two species of yeasts (Candida albicans and Rhodotorula bogoriensis). The results described in this paper show that TQP and (TQP)Sn(IV) did not inhibit the growth of S. aureus in the dark, but efficiently photosensitize the inactivation of this Gram-positive bacteria. These porphyrins have no appreciable photosensitizing activity towards Gram-negative bacteria. However, (TQP)Sn(IV) shows high dark toxicity against E. coli and P. aeruginosa. The free-base derivatives demonstrated dark activity only in the case of P. aeruginosa. We suppose that these meso-tetrakis(N-methyl-6-quinolinyl)-substituted porphyrins can bind to the Gram-negative bacteria outer membrane receptors that transported vitamin B12. The meso-substituted chlorins TQC and (TQC)Sn(IV) have shown similar efficiency in the dark- and photoinactivation of S. aureus. They revealed a middle level of dark toxicity towards Gram-negative bacteria. The Sn(IV)-complex of chlorin in comparison with free base and metalloporphyrins are more effective in photoinactivation of Gram-negative bacteria. Yeasts, such as Candida albicans and Rhodotorula bogoriensis are more sensitive to photodynamic inactivation as bacterial cells. The effects of (TQP)Sn(IV) and (TQC)Sn(IV) are more expressed than effects of free bases.

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Marine microorganisms have unique metabolic and physiological characteristics and are an important source of new biomolecules such as biosurfactants. Low molecular weight surfactants are glycolipids, phospholipids, fatty acids, lipopeptides and lipoproteins, and high molecular weight surfactants are mixtures of heteropolysaccharides, lipopolysaccharides, lipoproteins and proteins. The main general of bacteria that synthesize biosurfactants are Pseudomonas, Bacillus, Acinetobacter, Antarctobacter, Rhodococcus, Halomonas, Alcanivorax, Pseudoalteromonas and Marinobacter. This review examines the structure and function of biosurfactants isolated from marine microorganisms.