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In recent years, the problem of environmental pollution is becoming extremely serious. Especially, environmental pollution caused by textile dyes not only affects living organisms in the water but also affects human health. There are many methods applied to remove dyes in water; in which, photocatalysis has been proven to be an efficient method. The g-C3N4 is a polymer material with small bandgap energy (about 2,7 eV) as well as chemical and thermal stability in the ambient environment. In this study, the g-C3N4 material was successfully synthesized from urea calcined at 550 0C, and the modified materials αFe2O3/g-C3N4 were also successfully prepared by hydrothermal method. The synthesized materials were characterized by modern analytical techniques, such as SEM-EDX, XRD, UV-Vis, and FT-IR. The experimental results showed that synthesized materials have high efficiency in removing Congo Red dye in water under visible light irradiation. Especially, the 7% αFe2O3/g-C3N4 material had the best efficiency of Congo Red treatment, with an efficiency of up to 93.59% at pH 5 after 150 minutes.

Syringomycin E (SRE) is a phytotoxin produced by Pseudomonas syringae pv syringae with high potential as a safe and effective therapy for the control of human fungal infections and as a preservative for the food industry. In this study, 27 strains of P. syringae pv syringae were isolated from plums, potatoes, apricots and peaches, of which P. syringae pv syringae 120 (PS120) showed the highest SRE production levels. Furthermore, random mutagenesis induced by ultraviolet (UV) radiation resulted in the generation of a P. syringae pv syringae mutant that produced 30% more SRE than the parental strain PS120. To elucidate molecular mechanism underlying the higher SRE production ability of the mutant strain, syrB1 and syrB2 genes, which are known to be involved in SRE production, were cloned and sequenced. The nucleotide and amino acid sequences analysis showed that UV radiation induced numerous mutations at the AMP binding site on adenylation domain of syrB1, while no mutation was detected in syrB2 gene. Real-time polymerase chain reaction (PCR) results showed that expression of syrB1 gene in mutant strain was six-fold higher than that of PS120 strain. Taken together, these results suggest that the mutations at AMP binding site and overexpression of syrB1 were responsible for increased biosynthesis of SRE in P. syringae pv syringae. Key words: Antifungal protein, syringomycin E, UV mutagenesis, Pseudomonas syringae pv syringae, syrB1.