Redha H. Al-Hasan

Soil management enhancing hydrocarbon biodegradation in the polluted Kuwaiti desert

Oil-polluted Kuwaiti desert samples, exposed to the open air, were subjected to specific types of management, once every 2 weeks, throughout a year; control samples were not treated. The total amounts of extractable alkanes from the control samples remained fairly constant during the dry hot months, but decreased during the rainy months reaching, after 1 year, slightly more than one-half of the amount at zero time. This result demonstrates the self-cleaning of the Kuwaiti desert and the essential role of moisture in this process. Out of the eight types of management studied, the repeated fertilization of the polluted sample with 3% KNO3 solution was most efficient, reducing the extractable alkanes after 1 year to about one-third of zero reading. Repeated fertilization with treated sewage effluent was inhibitory to alkane biodegradation, probably because of increasing soil acidity. The latter inhibitory effect was annulled by liming. Repeated irrigation with 3% NaCl solution was inhibitory, but 1% NaCl solution slightly promoted alkane biodegradation. The various samples contained 1010–1011 oil-utilizing bacteria/g soil, predominantly Bacillus, Pseudomonas, Rhodococcus and Streptomyces. Oil-utilizing fungi were much less frequent and were predominantly Aspergillus and Penicillium species. The microbial numbers varied not only according to the type of soil management but also to the season.

Oil Pollution and Cyanobacteria

There is increasing evidence that ancient cyanobacteria were among the direct biogenic contributors to oil formation. This fact underlines the historical and ecological relations between these photosynthetic microorganisms and petroleum. Evidence that cyanobacteria are capable of hydrocarbon degradation is tentative, but preliminary studies indicate that some strains are capable of oxidizing aromatic and aliphatic oil constituents. Further, in cyanobacterial-dominated mats, the cyanobacteria live in natural association with hydrocarbon-degrading bacteria and fungi that occur in the cyanobacterial polysaccharide layers. Such mat associations flourish in oil-polluted coastal areas of subtropical regions like the Arabian Gulf. The combined activities of the cyanobacteria and the associated oil-degrading organotrophs appear to be crucial and effective in bioremediating such polluted environments.

Lipids, and their constituent fatty acids, ofPhaeocystis sp. from the Arabian Gulf

This paper reports on the firstPhaeocystis sp. (hereafterPhaeocystis) bloom in the Arabian Gulf. Total lipids from threePhaeocystis colonies sampled in November 1987 and in March and May 1988, comprised ca 11.0% of the dry biomass. Triacylglycerols (TG) and/or free fatty acids (FA) predominated in the lipids of all three samples. Polar lipids consisted of mixtures of phospholipids and glycolipids. Diacylglycerotrimethylhomoserines (DGTH) were present in all extracts, whilst conventional phospholipids only occurred in low concentrations. The predominant glycolipids were monogalactosyldiacylglycerols (MGDG) digalactosyldiacylglycerols (DGDG), sulfoquinovosyldiacylglycerols (SQDG) and steryl glycosides (SG). The predominant fatty acids in the total lipids of all three samples were palmitic (16:0) and oleic (18:1) acids. Total lipids of the November sample contained the smallest proportion of palmitic and the largest of polyunsaturated fatty acids (PUFA) — especially C16. The proportion of PUFA was considerable in individual polar lipids. C16 PUFA were more common in individual polar lipid classes of the November and March samples than that of May. The concentration of constituent C18 PUFA was relatively low. PUFA with chains longer than 18 C atoms only occurred in very low concentrations, and were confined to certain polar and nonpolar lipid classes of the November sample only.

Hydrocarbon accumulation by picocyanobacteria from the Arabian Gulf

Aims: The objective of this work was to study picocyanobacteria in the Arabian Gulf water in relation to oil pollution.

Enriching marine macroalgae with eicosatetraenoic (arachidonic) and eicosapentaenoic acids by chilling

SummaryTwelve macroalgae belonging to the Chlorophyta, Phaeophyta and Rhodophyta were collected from the Arabian Gulf. Field samples and samples that were first incubated at 5° C and 24° C in the light for 1 week were analysed for lipids and fatty acids. The lipid contents varied according to the macroalga and, within the Chlorophyta and Phaeophyta, some representatives accumulated more lipids at 5° C and others at 24° C. All samples of algae had similar lipid composition with only quantitative differences. The temperature did not have a common effect on the lipid composition of representative algae, although changes in the relative concentration of specific classes were recorded. The Phaeophyta and Rhodophyta were as a rule richer than the Chlorophyta in eicosatetranoic (20:4) and eicosapentaenoic (20:5) but poorer in linolenic (18:3) acids. In most of the algae, incubation at 5° C was associated with lowering the proportion of palmitic acid (16:0) in the total lipids, and, but only in the Phaeophyta and Rhodophyta, increasing the concentration of 20:4 and 20:5. These polyunsaturated fatty acids occurred in high levels in monogalactosyldiacylglycerols (MGDG) and digalactosyldiacylglycerols (DGDG) of the Phaeophyta and Rhodophyta but not the Chlorophyta, the MGDG and DGDG of which were rich in 18:3 and hexadecatrienoic acid (16:3).

Establishing oil-degrading biofilms on gravel particles and glass plates

Abstract A method is described for “artificially” establishing biofilms rich in hydrocarbon degrading bacteria on gravel particles and glass plates. The microbial consortia in the biofilms included in additions, filamentous cyanobacteria, picoplankton and diatoms. Phototrophic microorganisms were pioneer colonizers. Hydrocarbon utilizing bacteria, namely Acinetobacter calcoaceticus and nocardioforms were in part attached to filaments of cyanobacteria. In batch cultures, it was shown that those artificial biofilms had an attenuation effect on crude-oil in contaminated sea water samples. The potential use of these biofilms for preparing trickling filters (gravel particles), and in bioreactors (glass plates) for attenuating hydrocarbons in oily liquid wastes before their disposal in the open environment is suggested and discussed.

Effect of salinity on the lipid and fatty acid composition of the halophyteNavicula sp.: potential in mariculture

Navicula sp. (cf.N. tenelloides) was isolated from a salt marsh in Kuwait. The alga grew best with 0.5M NaCl, but abundant growth still occurred up to 2.5M NaCl. The total lipid content and the carotene to chlorophyll ratio of the cells increased with increasing salinity of the medium from 0.5 to 1.7M NaCl, but declined with 2.5M NaCl. Irrespective of the medium salinity, the major lipid class was that of triacylglycerols. The predominant fatty acids in the total lipids of cells grown at different NaCl concentrations were palmitic (16:0) and palmitoleic (16:1) acids; eicosapentaenoic acid (20:5) made up 8–9% of the total fatty acids. The fatty acid composition of the individual lipid classes of cells grown at different salinities is described. The highest concentration of 20:5 occurred in monogalactosyldiacylglycerols and digalactosyldiacylglycerols. In view of the rather small size of this diatom, its halotolerance and its fair content of 20:5, it is suggested as a potential food source for the mariculture industry.

Effects of light and dark incubation on the lipid and fatty acid composition of marine cyanobacteria

SUMMARY: The effect of light and dark incubation on the ultrastructure, pigments and lipids of five marine cyanobacteria was studied. All light-grown cyanobacteria contained in their lipid extracts the four major lipid classes characteristic of chloroplasts, namely monogalactosyldiacylglycerols, digalactosyldiacylglycerols, sulphoquinovosyldiacylglycerols, and phosphatidyl glycerols. However, the fatty acid patterns of the cyanobacterial total lipids and individual lipid classes were different from those of chloroplasts, and responded differently to dark incubation. In two cyanobacteria the fatty acid patterns of total lipids from light- and dark-incubated cultures were similar, but in the other three, dark incubation was associated with increased levels of oleic acid in the total lipids and individual lipid classes. The decrease of linolenic acid known to occur in lipids from photosynthetic eukaryotes in response to dark incubation was recorded only in Spirulina subsalsa. However, linolenic acid was not esterified in monogalactosyldiacylglycerols, as it is in chloroplasts. We also found the class of alcohol glycosides in three non-heterocystous cyanobacteria.

Oil-utilizing bacteria associated with fish from the Arabian Gulf

Aims:  The objectives were to count and identify the oil‐utilizing bacteria associated with fish, and to study their hydrocarbon‐degradation potential.

Arachidonic and Eicosapentaenoic Acids in Lipids of Bryum bicolor Dicks. Effects of Controlled Temperature and Illumination

Bryum bicolor Dicks. gametophytes maintained for 2 weeks in the light at 5 and 250C contained 9.8-11% total lipids. Dark incubation was associated with a slight decrease of these values. The nonpolar lipids of this moss consisted predominantly of triacyglycerols in addition to smaller proportions of sterols, fatty acids, steryl esters, and aliphatic alcohol esters. The predominant polar lipid classes were monogalactosyldiacyglycerols, digalactosyldiacylglycerols, sulfoquinovosyldiacyl- glycerols, and diacylglycerophosphoglycerols. Smaller proportions of diacylglycerophosphocholines, diacylglycerophosphoethanolamines, sphingomyelins, and steryl glycosides were also present. Lipids from plants maintained at 50C contained higher proportions of digalactosyldiacyglycerols and sul- foquinovosyldiacylglycerols than lipids from plants incubated at 250C. Arachidonic and eicosapen- taenoic acids were esterified in the nonpolar lipids, phospholipids, and sulfolipids, but were absent in the galactolipids. Incubation of the moss under continuous illumination at 50C was associated with increased concentrations of linolenic acid in monogalactosyldiacylglycerols and of arachidonic and eicosapentaenoic acids in the phospholipids and nonpolar lipids.