Vitamin requirements of hydrocarbon-utilizing soil bacteria

Bioremediation perspectives and progress in petroleum pollution in the marine environment: a review

The marine environment is often affected by petroleum hydrocarbon pollution due to industrial activities and petroleum accidents. This pollution has recalcitrant and persistent compounds that pose a high risk to the ecological system and human health. For this reason, the world claims to seek to clean up these pollutants. Bioremediation is an attractive approach for removing petroleum pollution. It is considered a low-cost and highly effective approach with fewer side effects compared to chemical and physical techniques. This depends on the metabolic capability of microorganisms involved in the degradation of hydrocarbons through enzymatic reactions. Bioremediation activities mostly depend on environmental conditions such as temperature, pH, salinity, pressure, and nutrition availability. Understanding the effects of environmental conditions on microbial hydrocarbon degraders and microbial interactions with hydrocarbon compounds could be assessed for the successful degradation of petroleum pollution. The current review provides a critical view of petroleum pollution in seawater, the bioavailability of petroleum compounds, the contribution of microorganisms in petroleum degradation, and the mechanisms of degradation under aerobic and anaerobic conditions. We consider different biodegradation approaches such as biostimulation, bioaugmentation, and phytoremediation.

Lipid accumulation in prokaryotic microorganisms from arid habitats

This review shall provide support for the suitability of arid environments as preferred location to search for unknown lipid-accumulative bacteria. Bacterial lipids are attracting more and more attention as sustainable replacement for mineral oil in fuel and plastic production. The development of prokaryotic microorganisms in arid desert habitats is affected by its harsh living conditions. Drought, nutrient limitation, strong radiation, and extreme temperatures necessitate effective adaption mechanisms. Accumulation of storage lipids as energy reserve and source of metabolic water represents a common adaption in desert animals and presumably in desert bacteria and archaea as well. Comparison of corresponding literature resulted in several bacterial species from desert habitats, which had already been described as lipid-accumulative elsewhere. Based on the gathered information, literature on microbial communities in hot desert, cold desert, and humid soil were analyzed on its content of lipid-accumulative bacteria. With more than 50% of the total community size in single studies, hot deserts appear to be more favorable for lipid-accumulative species then humid soil (≤20%) and cold deserts (≤17%). Low bacterial lipid accumulation in cold deserts is assumed to result from the influence of low temperatures on fatty acids and the increased necessity of permanent adaption methods.

Dynamics of bacterial populations during bench-scale bioremediation of oily seawater and desert soil bioaugmented with coastal microbial mats

This study describes a bench-scale attempt to bioremediate Kuwaiti, oily water and soil samples through bioaugmentation with coastal microbial mats rich in hydrocarbonoclastic bacterioflora. Seawater and desert soil samples were artificially polluted with 1% weathered oil, and bioaugmented with microbial mat suspensions. Oil removal and microbial community dynamics were monitored. In batch cultures, oil removal was more effective in soil than in seawater. Hydrocarbonoclastic bacteria associated with mat samples colonized soil more readily than seawater. The predominant oil degrading bacterium in seawater batches was the autochthonous seawater species Marinobacter hydrocarbonoclasticus. The main oil degraders in the inoculated soil samples, on the other hand, were a mixture of the autochthonous mat and desert soil bacteria; Xanthobacter tagetidis, Pseudomonas geniculata, Olivibacter ginsengisoli and others. More bacterial diversity prevailed in seawater during continuous than batch bioremediation. Out of seven hydrocarbonoclastic bacterial species isolated from those cultures, only one, Mycobacterium chlorophenolicum, was of mat origin. This result too confirms that most of the autochthonous mat bacteria failed to colonize seawater. Also culture-independent analysis of seawater from continuous cultures revealed high-bacterial diversity. Many of the bacteria belonged to the Alphaproteobacteria, Flavobacteria and Gammaproteobacteria, and were hydrocarbonoclastic. Optimal biostimulation practices for continuous culture bioremediation of seawater via mat bioaugmentation were adding the highest possible oil concentration as one lot in the beginning of bioremediation, addition of vitamins, and slowing down the seawater flow rate.

Bacterial communities associated with biofouling materials used in bench-scale hydrocarbon bioremediation

Biofouling material samples from the Arabian (Persian) Gulf, used as inocula in batch cultures, brought about crude oil and pure-hydrocarbon removal in a mineral medium. Without any added nitrogen fertilizers, the hydrocarbon-removal values were between about 10 and 50 %. Fertilization with NaNO3 alone or together with a mixture of the vitamins thiamine, pyridoxine, vitamin B12, biotin, riboflavin, and folic acid increased the hydrocarbon-removal values, to reach 90 %. Biofouling material samples harbored total bacteria in the magnitude of 10(7) cells g(-1), about 25 % of which were hydrocarbonoclastic. These numbers were enhanced by NaNO3 and vitamin amendment. The culture-independent analysis of the total bacterioflora revealed the predominance of the gammaproteobacterial genera Marinobacter, Acinetobacter, and Alcanivorax, the Flavobacteriia, Flavobacterium, Gaetbulibacter, and Owenweeksia, and the Alphaproteobacteria Tistrella, Zavarzinia, and others. Most of those bacteria are hydrocarbonoclastic. Culture-dependent analysis of hydrocarbonoclastic bacteria revealed that Marinobacter hydrocarbonoclasticus, Dietzia maris, and Gordonia bronchialis predominated in the fouling materials. In addition, each material had several more-specific hydrocarbonoclastic species, whose frequencies were enhanced by NaNO3 and vitamin fertilization. The same samples of fouling materials were used in four successive crude-oil-removal cycles without any dramatic loss of their hydrocarbon-removal potential nor of their associated hydrocarbonoclastic bacteria. In the fifth cycle, the oil-removal value was reduced by about 50 % in only one of the studied samples. This highlights how firmly biofouling materials were immobilizing the hydrocarbonoclastic bacteria.

Enhanced bioremediation of oil-polluted, hypersaline, coastal areas in Kuwait via vitamin-fertilization

There is no research published sofar on managements that could bioremediate hypersaline soils and water polluted with hydrocarbons. The objective of this study was to assess the effect of vitamin amendment on hydrocarbon removal by microorganisms indigenous to such hypersaline environments. We used in this study ten hydrocarbonoclastic bacterial species and five archaeal species that had been isolated by the conventional plating method on media containing oil as a sole carbon source, from a hypersaline (3-4 M NaCl) coastal area in Kuwait, and characterized by sequencing of their 16S rRNA coding genes. The oil and pure hydrocarbon consumption was measured by gas-liquid chromatography. The oil and pure hydrocarbon consumption potential of all microorganisms in media with hypersalinity was enhanced by vitamin fertilization. This was true for individual microorganisms in pure cultures as well as for microbial consortia in hypersaline soil and water samples used as inocula. Most effective vitamins were thiamin, pyridoxine and vitamin B12. Vitamin fertilization using vitamin rich wastes or byproducts could be an effective practice for enhancing bioremediation of oil contaminated hypersaline environments.

Aliphatic, cyclic, and aromatic organic acids, vitamins, and carbohydrates in soil: a review

Organic acids, vitamins, and carbohydrates represent important organic compounds in soil. Aliphatic, cyclic, and aromatic organic acids play important roles in rhizosphere ecology, pedogenesis, food-web interactions, and decontamination of sites polluted by heavy metals and organic pollutants. Carbohydrates in soils can be used to estimate changes of soil organic matter due to management practices, whereas vitamins may play an important role in soil biological and biochemical processes. The aim of this work is to review current knowledge on aliphatic, cyclic, and aromatic organic acids, vitamins, and carbohydrates in soil and to identify directions for future research. Assessments of organic acids (aliphatic, cyclic, and aromatic) and carbohydrates, including their behaviour, have been reported in many works. However, knowledge on the occurrence and behaviour of D-enantiomers of organic acids, which may be abundant in soil, is currently lacking. Also, identification of the impact and mechanisms of environmental factors, such as soil water content, on carbohydrate status within soil organic matter remains to be determined. Finally, the occurrence of vitamins in soil and their role in biological and biochemical soil processes represent an important direction for future research.

Curdlan-like exopolysaccharide production by Cellulomonas flavigena UNP3 during growth on hydrocarbon substrates

Cellulomonas flavigena UNP3, a natural isolate from vegetable oil contaminated soil sample has been studied for growth associated exopolysaccharide (EPS) production during growth on glucose, groundnut oil and naphthalene. The EPS showed matrix formation surrounding the cells during scanning electron microscopy. Cell surface hydrophobicity and emulsifying activity studies confirmed the role of EPS as bioemulsifier. Emulsifying activity was found to increase with time (0.2 U/mg for 10 min to 0.27 U/mg for 30 min). Emulsification index, E24 value increased with the increase in EPS concentration. Degradation of polyaromatic hydrocarbons was confirmed using gas chromatography analysis. FTIR analysis showed presence of characteristic absorbance at 895.10 cm(-1) for β-configuration of glucan. NMR studies also revealed EPS produced by C. flavigena UNP3 as a linear β-1, 3-D-glucan, and a curdlan like polysaccharide.