A cyanobacterial hepatotoxin, nodularin-Har, having a homoarginine instead of an arginine in nodularin, was isolated from Nodularia PCC7804. The structure was elucidated as 1 on the basis of 2D NMR and FABMS. The LD(50) (mouse ip) value of 1 was 70 microg/kg.
Chemically synthesized 4-hydroxybenzoate (4HBA) is widely used in the chemical and electrical industries as a material for producing polymers such as those of the liquid crystal type. Its alkyl esters, called parabens, have been the most widely used preservatives by the food and cosmetic industries. We report here for the first time a microorganism, a marine bacterium, which biosynthesizes these petrochemical products. The marine bacterial strain, A4B-17, which was found to belong to the genus Microbulbifer on the basis of its rRNA and gyrB sequences, was isolated from an ascidian in the coastal waters of Palau. Strain A4B-17 was, surprisingly, found to produce 10 mg/liter of 4HBA, together with its butyl (24 mg/liter), heptyl (0.4 mg/liter), and nonyl (6 mg/liter) esters. We therefore characterized 23 other marine bacteria belonging to the genus Microbulbifer, which our institute had previously isolated from various marine environments, and found that these bacteria also produced 4HBA, although with low production levels (less than one-fifth of that produced by A4B-17). We also show that the alkyl esters of 4HBA produced by strain A4B-17 were effective in preventing the growth of yeasts, molds, and gram-positive bacteria.Many marine bacteria are free living, while others are symbiotic in character or live in close association with macroorganisms. Thousands of secondary metabolites have been isolated from marine organisms and have been shown to exhibit one or more of a wide range of activities that can be broadly categorized as either attractant, deterrent, or protectant (13, 30). The purpose of our current project is to isolate currently unknown microorganisms from marine environments and to search for novel and/or industrially useful secondary metabolites that they may produce. We have been collecting sponge, alga, ascidian, sea glass, soft coral, sediment, and seawater samples from the Pacific waters of Japan, Palau, Micronesia, and Indonesia. More than 15,000 microorganisms have been isolated from the collected samples and subjected to phylogenetic analysis and screening processes. We report here for the first time a microorganism, a marine bacterium, which produces petrochemicals, i.e., 4-hydroxybenzoate (4HBA) and its alkyl esters (parabens). MATERIALS AND METHODSCollection of marine bacteria. Marine organisms and other marine samples, which were found to include bacteria accumulating 4HBA, had been collected in the years 1997 to 2004, as described in Table 1. Seawater was directly spread onto a 1.5% agar plate containing each medium and incubated at 30°C. Colonies that appeared on the plate were collected, and each pure culture was obtained. Marine organisms were disrupted physically, dissolved in seawater, and then used for isolating marine bacteria as described above. All isolates listed in Table 1 were able to grow well in Difco Marine Broth 2216 (MB) at 30°C with shaking.HPLC analysis. A portion of the culture (200 l) was collected each day and mixed with an equal amount of methanol. The mixture was s...
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