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Transfer of nitrogen fixation ability to plants, especially crops, is a promising approach to mitigate dependence on chemical nitrogen fertilizer and alleviate environmental pollution caused by nitrogen fertilizer run-off. However, the need to transfer a large number of nitrogen fixation (nif) genes and the extreme vulnerability of nitrogenase to oxygen constitute major obstacles for transfer of nitrogen-fixing ability to plants. Here we demonstrate functional expression of a cyanobacterial nitrogenase in the non-diazotrophic cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis 6803). A 20.8-kb chromosomal fragment containing 25 nif and nif-related genes of the diazotrophic cyanobacterium Leptolyngbya boryana was integrated into a neutral genome site of Synechocystis 6803 by five-step homologous recombination together with the cnfR gene encoding the transcriptional activator of the nif genes to isolate CN1. In addition, two other transformants CN2 and CN3 carrying additional one and four genes, respectively, were isolated from CN1. Low but significant nitrogenase activity was detected in all transformants. This is the first example of nitrogenase activity detected in non-diazotrophic photosynthetic organisms. These strains provide valuable platforms to investigate unknown factors that enable nitrogen-fixing growth of non-diazotrophic photosynthetic organisms, including plants.

Fattiviracin A1, showed potent antiviral activities against herpes simplex virus type 1 (HSV-1), varicella-zoster virus (VZV), influenza A virus and human immunodeficiency virus type 1 (HIV-1). It showed no cytotoxicity against Vero cells. Fattiviracin A1 exhibited no significant antibacterial or antifungal activities. Treatment of HSV-1 with fattiviracin A1 decreased its infectivity to Vero cells. The mechanism of its antiviral activity may be due to inactivation of the viral particles and inhibition of viral entry into host cells.

A novel antiherpetic agent, fattiviracin A1, was isolated from the culture broth of strain No. 2445 identified as Streptomyces microflavus. It was purified through 1-butanol extraction, column chromatographies on Diaion HP-10 and silica gel and HPLC using a reverse phase column. The structure of fattiviracin A1 was determined by several spectroscopic experiments and chemical degradations. It is a new macrocyclic diester consisting of four D-glucose units and two (C24 and C33) hydroxy fatty acids. It is closely related to cycloviracins B1 and B2, but differs from these known compounds in both the length of its side chain and the sugar moiety.

A new antiherpetic agent, AH-1763 IIa, was isolated from the culture broth of strain No. 1763 identified as Streptomyces cyaneus. It was purified through column chromatographies of Diaion HP-10 and silica gel. The structure was determined to be 11-hydroxy-5-methyl-2-(2-hydroxy-1-methylpropyl)-4H-anthraceno [1,2-b]pyran-4,7,12-trione by several spectroscopic experiments, that is a new antibiotic belonging to pluramycin-group.

A new antiherpetic agent, AH-758, was isolated from the culture broth of Streptomyces sp. strain No. 758. The structure was determined by NMR special analyses to be a new antibiotic belonging to bafilomycin group containing (5-oxo-2-pyrrolin-2-yl) methyl fumarate in its C-21.