[Research on search of the carotenoid-producing microorganisms in marine area and the improvement of production ratio].

Carotenoids are liposoluble pigments widely distributed in nature. More than 750 carotenoids are isolated from natural sources, but only a few kinds are used industrially. The production of carotenoid by microorganisms is to be expected, but few carotenoids originate from living things on land. And there is little knowledge about carotenoid-producing microorganisms in the oceans. The possibility still exists of discovering new carotenoid-producing microorganisms. Sunlight is very strong in subtropical regions. The surface of the sea and coral reefs in these regions is a severe environment for growth of microorganisms. While such conditions produce reactive oxygen species, the continuing strong irradiation can also lead to damaging and lethal photo-oxidative reactions. Many undiscovered microorganisms may possess protective mechanisms such as anti-oxidative activities for survival in this environment. This study focused on marine microorganisms inhabiting coral reefs in the Okinawa area, especially carotenoid-producing bacteria possessing anti-oxidative activities. Many carotenoid-producing microorganisms were collected from subtropical ocean areas (a total of 334 strains of pigmented microorganisms), and the chemical composition, some culture conditions and genetic characteristics of the carotenoids from these microorganisms were examined. Furthermore, similar research was performed using some creatures from the ocean surrounding Kochi Prefecture.

Phylogenetic analysis of carotenoid-producing marine microorganisms around the coral reefs of the Kerama Islands of Okinawa.

Seawater sample from the coral reefs of the Kerama Islands of Okinawa were assessed for the presence of carotenoid-producing bacteria. Results of 16S rDNA analysis of the bacteria obtained from the isolated bacteria showed unique patterns that were different from those of the bacteria obtained from the ordinary marine area. Phylogenetic analysis revealed a slight correlation with the statistical analysis of the PDA chart patterns. The results suggest that useful materials for human health such as carotenoids can be extracted from many carotenoid-producing bacteria such as those found the coral reefs the Kerama Islands.

Culture characteristics of carotenoid-producing filamentous fungus T-1, and carotenoid production.

The culture characteristics, carotenoid production, and associated biosynthetic pathway of strain T-1 were examined. As a result of examining the culture temperature and light irradiation, an increase of neurosporaxanthin and neurosporaxanthin beta-D-glucopyranoside was observed at a low temperature and 0 lx. It was suggested that highly polar carotenoids, such as neurosporaxanthin, and carotenoid glycosides were involved in the stabilization of membrane during nutrition storage other than the defense function of fungus bodies. Strain T-1 produced lycopene, beta-carotene, gamma-carotene, torulene, neurosporaxanthin, and neurosporaxanthin beta-D-glucopyranoside, as assessed by HPLC, LC-MS, and NMR analysis. Carotenoid biosynthesis begins with neurosporene, passing to lycopene and gamma-carotene through cyclization, and produces beta-carotene. In addition, it is saturated, gamma-carotene is converted to torulene, and neurosporaxanthin is produced. Thus, the carotenoid biosynthetic pathway in strain T-1 was estimated.

A new carotenoid glycosyl ester isolated from a marine microorganism, Fusarium strain T-1.

A new carotenoid glycosyl ester, neurosporaxanthin beta-D-glucopyranoside (2), together with neurosporaxanthin (1), beta-carotene, gamma-carotene, and torulene were isolated from cultured cells of a marine microorganism, strain T-1, which was identified as Fusarium sp. Their structures were determined by chemical and spectral data.