Optimization of lipid production in the oleaginous bacterium Rhodococcus erythropolis growing on glycerol as the sole carbon source

The growth of an oleaginous bacteria strain Rhodococcus erythropolis on glycerol was studied. Lipid accumulation was influenced by the glycerol concentration, nitrogen source, nitrogen concentration, pH medium, incubation time and aeration rate. Under the best optimized flask culture medium; 30 g/L glycerol plus 0.75 g/L urea, incubation temperature at 30°C, agitation rate of 150 rpm and 96 h of cultivation time, 3.93 g/L of dry biomass, 1.84 g/L cellular lipid accumulation and 45.8% accumulated lipid of total dry biomass were produced. The scaling up of R. erythropolis in bioreactors yielded the biomass and lipid content of 11.74 g/L and 14.1% of total dry biomass, respectively. The lipid composition of oleaginous microorganisms contained a high proportion of C16 and C18 fatty acids. The extracted lipids were mainly 16.48% C14:1, 16.69% C16:1, 20.16% C16:0, 18.90% C18:1. R. erythropolis could be directed to using raw glycerol obtained from biodiesel by-product as substrate, in order to accumulate lipids for biodiesel production.Key words: Rhodococcus eryhropolis, glycerol, lipid accumulation, biodiesel, fatty acid composition

Ultrastructural changes of the digestive tract of Pomacea canaliculata exposed to copper at lethal concentration

The present study was undertaken to elucidate the basis of cellular reactions and to verify the suitability of Pomacea canaliculata digestive tract ultrastructure as a biomarker for assessing the Cu pollution in freshwater environments. Two-month-old P. canaliculata were exposed to 96-h lethal concentration of Cu (0.15 mg L-1) for 96 h. Electron microscope investigations showed different alterations of organelles in the epithelial cells lining the esophagus and intestine. The most striking changes were damages to the mitochondria, RER, and nucleus typified by loss of cristae and degeneration of mitochondria; degranulation and fragmentation of RER. In nucleus, karyolysis and rupture of nuclear envelope were observed. These changes were attributed to membrane destabilization and increased membrane permeability to ions under the influence of toxicants or heavy metals. These findings indicate the possibility of using the P. canaliculata as biomonitor for Cu contamination in the freshwater environment

Heavy metal concentrations in duck eggs and potential human health risk via consumption

Heavy metals commonly found in environmental matrices are from natural or anthropogenic activities. Their contamination effects especially on human health from non-degradable properties are of major concern. The aims of this study, thus, were to determine Cd, Cu, Fe, Mn, Ni, Pb and Zn residues in duck eggshells, yolk and albumin, and to investigate the correlations of these metal residues with the surrounding environmental media (soil, water, and feed). Target hazard quotient (THQ) of individual heavy metal was used to evaluate potential human health risk via egg consumption. Thirty duck egg samples were randomly collected from each free range laying duck farm (total of 8 farms). The samples collected were analyzed for heavy metal concentrations using the flame atomic absorption spectrometry (FAAS). Results showed that average concentrations of Fe (71.96±1.33 μg/g dw) in yolk and Pb (6.76±0.21 μg/g dw) in albumin were significantly highest when compared to other investigated metals, whereas Cu concentration was mostly found in egg shells. In addition, the predominantly found metal in soil samples was Fe, whereas in water and feed samples were Ni and Pb, respectively. Principle component analysis (PCA) revealed that the concentrations of heavy metals found in eggshells and egg contents are highly correlated with their concentrations in the surrounding water and soil matrices as well as feed. The THQs for Pb, which were greater than 1, indicated that there could be potential for human health risks upon consumption of contaminated duck eggs

ผลของการใช้สารควบคุมการเจริญเติบโตร่วมกันต่อความเป็นพิษของเฮกซะคลอโรไซโคลเฮกเซนในข้าวโพดข้าวเหนียว

วารสารวิชาการและวิจัย มทร.พระนคร, 10 (1) : 65-76The effects of plant growth regulators alone or in combination on Hexachlorocyclohexane (HCH) phytotoxicity were studied. Waxy corn seeds were immersed in different plant growth regulators, that are 1) 2 mg/l Indolebutyric acid (IBA) 2) 2 mg/l Thidiazuron (TDZ) 3) 2 mg/l Gibberellic acid (GA3) 4) 1 mg/l IBA + 1 mg/l TDZ 5) 1 mg/l TDZ + 1 mg/l GA3 and 6) 1 mg/l IBA + 1 mg/l GA3, then sawn in 30 mg/kg HCH-contaminated soil or non-contaminated soil for 10 days. All plant growth regulators could enhance shoot and root dried weight of waxy corn seedlings in non-contaminated soil. Only 2 mg/l GA3 could enhance root length of waxy corn seedlings in non-contaminated soil. In HCH-contaminated soil, only 2 mg/l TDZ could increase shoot dried weight of waxy corn seedlings. Also, 2 mg/l IBA or 1 mg/l IBA and1 mg/l GA3 could increase root fresh weight of waxy corn seedlings. The exposure with HCH in soil did not affect to shoot and root tissue even though the growth of shoot and root were inhibited. However, the exposure with HCH and receive exogenous plant growth regulator induced aerenchyma formation in cortex and pith of waxy corn root.Rajamangala University of Technology Phra Nakho

The Pallial Organs of Haliotis Asinina Linnaeus (Gastropoda : Haliotidae)

ABSTRACT The pallial organs of Haliotis asinina are composed of gills, osphradium, hypobranchial gland, kidney and heart. The bipectinate paired gills are on the left and right sides of the mantle cavity. The gill epithelium is composed of ciliated columnar cells and occasional mucous cells. The paired osphradia are long, slender and lie anteriorly on each side of the mantle near the gills. The ciliated sensory epithelial cells are very tall and closely packed. The paired hypobranchial glands are fused and lie along almost the entire length of the mantle. The left hypobranchial gland is more prominent than the right one. They are composed of mucous gland cells. The paired kidneys are at the postero-dorsal part of the mantle and lie anteriorly to the heart. The right kidney contains tubulo-asini with light squamous or cuboidal epithelial cells. The left kidney contains densely packed irregular cuboidal epithelial cells. The heart is at the posterior end of the mantle connecting to the gills and is composed of one ventricle and two auricles. The wall of the auricles contains strands of muscle and fibrous tissue whereas the ventricle has thick muscular walls

The Pallial Organs of Haliotis Asinina Linnaeus

The pallial organs of Haliotis asinina are composed of gills, osphradium, hypobranchial gland, kidney and heart. The bipectinate paired gills are on the left and right sides of the mantle cavity