Effect of carbon source on the biotransformation enzymesin Serratia marcescens

A microorganism capable of degrading camphor as the sole source of carbon was isolated from soil. The strain was identified as Serratia marcescens (NCIM 5115). The strain when grown in the peptone–glucose medium showed a doubling time of 2.7 h. This microorganism showed the presence of cytochrome P-450, cytochrome b₅ and the activities of cytochrome c reductase, dichlorophenol indophenol reductase, aminopyrine-N-demethylase and steroid 11--hydroxylase. A significant increase in all activities was observed when cells were incubated for 3h in a medium containing either 0.2% camphor, 1.0% n-hexadecane or 0.1% naphthalene when compared to the peptone–glucose medium.     

Inducibility of biotransformation enzymes in Serratia marcescens

A significant increase in the levels of electron transport components and biotransformation enzymes was observed when cells of Serratia marcescens were incubated for 3 h or cells grown for 8 h (exponential growth phase) in synthetic medium containing either 1.0% ethanol or 5.0% veratrole when compared to peptone-glucose medium. Phenobarbital was found to be a poor inducer of monooxygenase.     

Influence of Dimensions of UHMW-PE Protuberances on Sliding Resistance and Normal Adhesion of Bangkok Clay Soil to Biomimetic Plates

A number of investigations into application of polymers for macro-morphological modification of tool surface have been carried out. These researches, with extensive stress on convex or domed protuberations as one of the widely used construction units, have tried to harness benefits from using polymers in agriculture. Ultra high molecular weight polyethylene （UHMW-PE） has proved an emerging polymer in its application to reduce soil adhesion. This research was conducted to study the effect of shape （flat, semi-spherical, semi-oblate, semi short-prolate and semi long-prolate） and dimensions （base diameter and dome height） on sliding resistance and normal adhesion of biomimetic plates. To incorporate both shape and size, a dimensionless ratio of height to diameter （HDR） was introduced to characterize the effect of construction unit＇s physique. Experiments were conducted in Bangkok clay soil with dry （ 19.8% d.b.）, sticky （36.9% d.b.） and flooded （60.1% d.b.） soil conditions respectively. Soil at sticky limit exhibited the highest sliding resistance （77.8 N） and normal adhesion （3 kPa to 7 kPa）, whereas these values were 61.7 N and 〈0.2 kPa in dry, and 53.7 N and 0.5 kPa to 1.5 kPa in flooded soil conditions. Protuberances with HDR ≤ 0.5 lowered sliding resistance by 10% - 30% and the same reduced normal adhesion by 10% - 60%. The amount of reduction in both sliding resistance and normal adhesion was higher in flooded soil. Lighter normal loads obviously produced lesser resistance and adhesion.