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Zingiber zerumbet (L.) Smith leaf and rhizome oils, obtained by hydrodistillation, were analyzed by gas chromatography mass spectroscopy (GC-MS). Twentynine components were identified in the leaf oil. The major components were zerumbone (37.0%); a-caryophyllene (16.4%) and camphene (9.2%). Thirty components were identified in rhizome oil with the main components being in zerumbone (46.8%); a-caryophyllene (19.0%) and 1,5,5,8-tetramethyl-12-oxabicyclo[9.1.0]dodeca-3,7-diene (4.3%). The compositions of both oils varied qualitatively and quantitatively.

GC-MS analysis of essential oil of Blumea balsamifera (L.) DC. leaf revealed the presence of 50 components, contributing to 99.07% of the oil. The dominant components in the oil from leaves were borneol (33

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Essential oil from the rhizomes of two types of Curcuma longa, yellow and red originated in Bangladesh was analyzed by GC-MS. 54 compounds have been identified from the yellow type of which the major compounds are ar-tumerone (27.78%), tumerone (17.16%), culone (13.82%), 2-carene (4.78%), zingiberene (4.37%) and β-sesquiphellandrene (5.57%). The red type contained 39 compounds with carvacrol (21.14%), citral (13.91%), methyleugenol (7.31%), geraniol (6.99%), menthol (5.11%) and caryophyllene oxide (4.14%) as major constituents.

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We have identified coproporphyrins including structurally new zincmethylphyrins I and III as growth factors A-F for the previously uncultured bacterial strain, Leucobacter sp. ASN212, from a supernatant of 210 l of Sphingopyxis sp. GF9 culture. Growth factors A-F induced significant growth of strain ASN212 at the concentrations of picomolar to nanomolar which would otherwise be unculturable in liquid medium or on agar plate. More interestingly, we found that the growth factors functioned as self-toxic compounds for the growth-factor producing strain GF9 at the picomolar to nanomolar levels. As a variety of bacteria could potentially produce coproporphyrins, our findings suggest that these compounds function as a novel class of signal molecules across a boundary at phylum level in the complex bacterial communities.