Stimulation of Lipase Production During Bacterial Growth on Alkanes

Acinetobacter lwoffi strain O₁₆, a facultative psychrophile, can grow on crude oil, hexadecane, octadecane, and most alkanes when tested at 20 but not at 30°C. Growth occurred on a few alkanes at 30°C but after a longer lag than at 20°C. Cells grown on alkanes as sole carbon sources had high levels of cell-bound lipase. In contrast, previous work has shown that those grown on complex medium produced cell-free lipase and those grown on defined medium without alkanes produced little or no lipase. Low concentrations of the detergent Triton X-100 caused the liberation of most of the lipase activity of alkane-grown cells and increased total lipase activity. When ethanol and hexadecane were both present in a mineral medium, diauxic growth occurred; until the ethanol was completely used up, hexadecane was not utilized, and the lipase activity was very low. When growth on hexadecane began, lipase activity increased, reaching a level 50- to 100-fold higher than that of cells growing on ethanol. A similar pattern of lipase formation and hexadecane utilization was observed with Pseudomonas aeruginosa. Whenever A. lwoffi and other bacteria degraded alkanes they exhibited substantial lipase activity. Not all bacteria that produced lipase, however, could attack alkanes. Bacteria that could not produce lipase did not attack alkanes. The results suggest that a correlation may exist between lipase formation and alkane utilization.     

Induced plant volatiles allow sensitive monitoring of plant health status in greenhouses

A novel approach to support the inspection of greenhouse crops is based on the measurement of volatile organic compounds emitted by unhealthy plants.This approach has attracted some serious interest over the last decade. In pursuit of this interest, we performed several experiments at the laboratory-scale to pinpoint marker volatiles that can be used to indicate certain health problems. In addition to these laboratory experiments, pilot and model studies were performed in order to verify the validity of these marker volatiles under real-world conditions. This paper provides an overview of results and gives an outlook on the use of plant volatiles for plant health monitoring.Key words: plant health, volatiles, plant pathogens, plant infection     

Effect of man-made electromagnetic fields on common <i>Brassicaceae Lepidium sativum</i> (cress d’Alinois) seed germination: a preliminary replication study

Under high levels of radiation (70-100 µW/m2 =175 mV/m), seeds of Brassicaceae Lepidium sativum (cress d’Alinois) never germinated. In fact, the first step of seeds’ germination ‒ e.g. imbibitions of germinal cells ‒ could not occur under radiation, while inside the humid compost such imbibitions occurred and roots slightly developed. When removed from the electromagnetic field, seeds germinated normally. The radiation was, thus, most likely the cause of the non-occurrence of the seeds’ imbibitions and germination.     

Cytoplasmic dynein could be key to understanding neurodegeneration

A new mouse mutation, Sprawling, highlights an essential role for the dynein heavy chain in sensory neuron function, but it lacks the ability of other known heavy-chain mutations to ameliorate neurodegeneration due to defective superoxide dismutase.