Optimization of Culture Conditions for Enhanced Antimicrobial Activity of Rhodococcus erythropolis VLK-12 Isolated from South Coast of Andhra Pradesh, India.

Aims: To Isolate and characterize the antimicrobial actinomycetes from the marine habitats of south coast of Andhra Pradesh, India. Place and Duration of the Study: Marine habitats of south coast of Andhra Pradesh, India, between June 2011 and July 2012. Methodology: The soil samples were collected, pre-treated and plated on yeast extractmalt extract dextrose agar medium. Identification of the strain was carried out by employing the polyphasic taxonomical studies including the 16S rRNA sequence based analysis. Phylogenetic tree was constructed using the Molecular Evolutionary Genetic Analysis (MEGA) version 5. The influence of culture conditions and the effect of environmental factors on the biomass and antimicrobial activy\ity of the strain was the focus of this study. Results: A total of 20 actinobacteria were isolated from the marine habitats of south coast of Andhra Pradesh, India, and screened for antimicrobial activity against test bacteria and fungi. The potent bioactive metabolite producing strain was designated as VLK-12. Further polyphasic studies revealed that the Isolate VLK-12 belongs to the genera Rhodococcus. Phylogenetic analysis of 16S rRNA sequencing studies revealed that the strain is closely related to Rhodococcus erythropolis. The crude ethyl acetate extract obtained by culturing the strain on YMD inhibited Gram positive and Gram negative bacteria along with fungi. Conclusion: Rhodococcus erythropolis isolated from the marine habitats of south coast of Andhra Pradesh exhibited antimicrobial activity against pathogens.

BIODEGRADACIÓN DE RESIDUOS DE ESTACIONES DE SERVICIO Y LAVADEROS INDUSTRIALES POR LA CEPA Rhodococcus erythropolis ohp-al-gp / Biodegradation Waste of the Stations Service by Rhodococcus erythropolis ohp-al-gp

La cepa Rhodococcus erythropolis ohp-al-gp fue aislada de un suelo contaminado con aceite de turbinas de la zona norte de la provincia de San Cruz, Argentina. Dado su potencial en la bioremediación, el objetivo del trabajo fue conocer las habilidades para la degradación de compuestos puros y mezclas de hidrocarburos, como también degradación en presencia y ausencia de nitrógeno de gasoil medido por cromatografía gaseosa. La cepa posee la capacidad de utilización de los siguientes hidrocarburos: gasoil, kerosene, aceite lubricante, pristano, hexano, heptano, octano, pentadecano y hexadecano. La cepa R. erythropolis ohp-al- gp presenta un excelente potencial de biorremediación de hidrocarburos conflictivos como son los aceites lubricantes, su posible empleo en la eliminación de barros provenientes de lavados de motores o de estaciones de servicio sería su aplicación más importante. La velocidad de degradación, en condiciones óptimas de cultivo, le confiere una ventaja adicional. Además, posee una degradación baja en ausencia de nitrógeno, factor limitante y frecuente en los suelos patagónicos.

The strain Rhodococcus erythropolis ohp-al-gp was isolated from turbine oil contaminated soil from northern San Cruz province, Argentina. Because of its potential in bioremediation, the aim was to know the abilities for degradation of pure compounds and mixtures of hydrocarbons, as well as degradation in the presence and absence of diesel nitrogen measured by gas chromatography. The strain possesses the ability to use diesel, kerosene, lubricating oil, pristane, hexane, heptane, octane, pentadecane and hexadecane. R. erythropolis ohp-al-gp has excellent potential for bioremediation of hydrocarbons, which are conflictives as lubricating oils, their potential use in removing mud from washing engines or gas stations would be its most important application. The degradation rate in optimal culture conditions, gives it an additional advantage. It also has a low degradation in the absence of nitrogen, a frequent limiting factor in Patagonian soils.

Biosurfactant production by Rhodococcus erythropolis and its application to oil removal

The influence of different nutrients on biosurfactant production by Rhodococcus erythropolis was investigated. Increasing the concentration of phosphate buffer from 30 up through 150 mmol/L stimulated an increase in biosurfactant production, which reached a maximum concentration of 285 mg/L in shaken flasks. Statistical analysis showed that glycerol, NaNO3,MgSO4 and yeast extract had significant effects on production. The results were confirmed in a batchwise bioreactor, and semi-growth-associated production was detected. Reduction in the surface tension, which indicates the presence of biosurfactant, reached a value of 38 mN/m at the end of 35 hours. Use of the produced biosurfactant for washing crude oil-contaminated soil showed that 2 and 4 times the critical micellar concentration (CMC) were able to remove 97 and 99 percent of the oil, respectively, after 1 month of impregnation.

Study on the Bioemulsifier Produced by a Hydrocarbon- degrading Strain T7-2 and Its Physic-chemical Properties / 微生物学通报

A low-temperature hydrocarbon-degrading strain T7-2, isolated from sea-mud of Bohai polluted area and identified as Rhodococcus erythropolis, was found to produce an extracellular, nondialyzable emul- sifying agent (referred to as bioemulsifier) when grew with hexadecane as carbon source. The results showed that, this bioemulsifier which could remarkably emulsify hydrocarbons such as diesel oil, is consisted of three parts-carbohydrates, lipids and proteins, the proportion of which was 55.43:31.24:12.65. The mono- saccharide compositions were identified as mannose and rhamnose; the lipid compositions included de- canoic acid, lauric acid, hexadecanoic acid and stearic acid, and the protein constituents were composed of sixteen amino acids. Besides, according to the study of the physic-chemical properties of the bioemulsifier, it possesses the obvious advantages of character stability, high function efficiency and wide adaptation range, therefore this bioemulsifier is believed to have extensive application values for bioremediation of marine oil pollution, petroleum exploitation and etc.