Analysis of Recent Patenting Activities in the Field of Bioremediation of Petroleum Hydrocarbon Pollutants Present in the Environment.

BACKGROUND: In today's world one of the major environmental problems is the contamination of aquatic or terrestrial ecosystem due to spillage of hydrocarbon compounds produced due to various activities related to the petrochemical industry. In recent years, bioremediation has emerged as a promising technology for the restoration of these contaminated sites in an ecofriendly way. OBJECTIVE: The aim of present review literature is the compilation of patent documents on bioremediation of petroleum hydrocarbon pollutants to know technological advancements in this field. METHODS: This analysis was based on various criteria i.e. patenting trend over time, country-wise and assignee-wise comparisons and types of technology used in various patents. Some publicly available patent databases were used to retrieve the patent information from the year 2000 to 2016. RESULTS: Patent applications were retrieved and it was observed that different types of technological approaches were used in developing the patents. United States accounted for maximum patent publications, followed by China, Korea, Japan, Russia, Great Britain, Mexico, India and Canada in developing bioremediation technologies. US based organization DU PONT is the leading group as patent assignee followed by Biosaint Co. Ltd in Korea. CONCLUSION: Patenting activity in the field of bioremediation of petroleum hydrocarbon was not much commendable in the early 20th century. However, an increased trend was observed in the past few years. Further contribution in this aspect would help in stabilizing various global environmental as well as economic issues.

Phytoremediation of abandoned crude oil contaminated drill sites of Assam with the aid of a hydrocarbon-degrading bacterial formulation.

Environmental deterioration due to crude oil contamination and abandoned drill sites is an ecological concern in Assam. To revive such contaminated sites, afield study was conducted to phytoremediate four crude oil abandoned drill sites of Assam (Gelakey, Amguri, Lakwa, and Borholla) with the aid of two hydrocarbon-degrading Pseudomonas strains designated N3 and N4. All the drill sites were contaminated with 15.1 to 32.8% crude oil, and the soil was alkaline in nature (pH8.0-8.7) with low moisture content, low soil conductivity and low activities of the soil enzymes phosphatase, dehydrogenase and urease. In addition, N, P, K, and C contents were below threshold limits, and the soil contained high levels of heavy metals. Bio-augmentation was achieved by applying Pseudomonas aeruginosa strains N3 and N4 followed by the introduction of screened plant species Tectona grandis, Gmelina arborea, Azadirachta indica, and Michelia champaca. The findings established the feasibility of the phytoremediation of abandoned crude oil-contaminated drill sites in Assam using microbes and native plants.

Rhizoctonia wilt suppression of brinjal (Solanum melongena L) and plant growth activity by Bacillus BS2.

An antibiotic-producing and hydrogen-cyanide-producing rhizobacteria strain Bacillus BS2 showed a wide range of antifungal activity against many Fusarium sp. and brinjal wilt disease pathogen Rhizoctonia solani. Seed bacterization with the strain BS2 promoted seed germination and plant growth in leguminous plants Phaseolus vulgaris and non-leguminous plants Solanum melongena L, Brassica oleracea var. capitata, B. oleraceae var. gongylodes and Lycopersicon esculentum Mill in terms of relative growth rate, shoot height, root length, total biomass production and total chlorophyll content of leaves. Yield of bacterized plants were increased by 10 to 49% compared to uninoculated control plants. Brinjal sapling raised through seed bacterization by the strain BS2 showed a significantly reduced wilt syndrome of brinjal caused by Rhizoctonia solani. Control of wilt disease by the bacterium was clue to the production of antibiotic-like substances, whereas plant growth-promotion was due to the activity of hydrogen cyanide. Root colonization study confirmed that the introduced bacteria colonized the roots and occupied 23-25% of total aerobic bacteria, which was confirmed using dual antibiotic (nalidixic acid and streptomycin sulphate) resistant mutant strain. The results obtained through this investigation suggested the potentiality of the strain BS2 to be used as a plant growth promoter and suppressor of wilt pathogen.

Biological activity of secondary metabolites produced by a strain of Pseudomonas fluorescens.

Biological activity of secondary metabolites produced by a plant-growth-promoting Pseudomonas fluorescens was evaluated. The strain produced antibiotics phenazine (PHE), 2,4-diacetylphloroglucinol (PHL) and siderophore pyoverdin (PYO) in standard King's B and succinic acid media, respectively. After extraction, PYO was identified by comparing the UV-spectra and moss-green color development after 'diazotized sulfanilic acid' (DSA) spray in TLC. PHE and PHL were identified by comparing standard compounds on TLC and orange-color development immediately after DSA spray. In vitro antibiosis study of the metabolites revealed their antibacterial and antifungal activity against bacterial test organisms Corynebacterium sp., Mycobacterium phlei and M. smegmatis and test fungi Fusarium moniliforme, F. oxysporum, F. semitectum, F. solani and Rhizoctonia solani. A statistically significantly higher plant growth was recorded in siderophore-amended plantlets under gnotobiotic conditions whereas PHE and PHL did not show any plant-growth-promoting activity. These results support the importance of the secondary metabolites produced by the strain P. fluorescens in enhancing plant growth and in controlling fungal and bacterial pathogens.

Plant disease suppression and growth promotion by a fluorescent Pseudomonas strain.

An antibiotic- and siderophore-producing Pseudomonas strain isolated from virgin soils (with forest trees) displayed in vitro antibiosis against many plant pathogenic fungi. The presence of iron had no effect on this in vitro antibiosis. Seed bacterization improved germination, shoot height, root length, fresh and dry mass, enhanced yield and chlorophyll content of leaves in the five test crop plants under field conditions. Seed bacterization also reduced the number of infected brinjal plants grown in soil infested with Rhizoctonia solani. The strain produced a yellowish green siderophore in the standard succinate medium and both siderophore and a yellow viscous antibiotic compound in King's B medium. The results confirmed that the plant growth promotion was due to siderophore production whereas the disease suppression was due to the antibiotic substance.