Morphological and metabolic shifts of Yarrowia lipolytica induced by alteration of the dissolved oxygen concentration in the growth environment.

Yarrowia lipolytica, an ascomycete with biotechnological potential, is able to form either yeast cells or hyphae and pseudohyphae in response to environmental conditions. This study shows that the morphology of Y. lipolytica, cultivated in batch cultures on hydrophilic (glucose and glycerol) and hydrophobic (olive oil) media, was not affected by the nature of the carbon source, nor by the nature or the concentration of the nitrogen source.

The olive mill wastewater as substrate for single cell oil production by Zygomycetes.

The conversion of olive mill wastewater (OMW) into high added value lipids containing polyunsaturated fatty acids (PUFA), in parallel with a significant phenolic removal by selected strains of Zygomycetes, is reported here for the first time. The growth of Mortierella isabellina, Mortierella ramanniana, Cunninghamella echinulata, Mucor sp., Thamnidium elegans and Zygorhynchus moelleri on solidified media was not significantly affected by the presence of OMW used in the growth medium up to 50% (v/v).

Lipids containing polyunsaturated fatty acids synthesized by zygomycetes grown on glycerol.

Several strains of Zygomycetes cultivated on glycerol produced mycelia rich in lipids containing higher amounts of neutral lipids (NL) than glycolipids plus sphingolipids and phospholipids (P), while biosynthesis of P in Mortierella ramanniana, Mucor sp., and Cunninghamella echinulata occurred though NL accumulation process was in progress. Polyunsaturated fatty acids (PUFA) concentration gradually decreased in all lipid fractions of M.

Metabolic activities of biotechnological interest in Yarrowia lipolytica grown on glycerol in repeated batch cultures.

The growth of Yarrowia lipolytica on glycerol was studied in bioreactor repeated batch cultures and three distinct phases, namely biomass production phase, lipogenic phase and citric acid production phase were identified during growth cycle. In each phase, yeast cells were characterised by specific morphological and biochemical features. Though high activity of NAD(+) dependent iso-citric dehydrogenase (NAD(+)-ICDH) was detected during biomass production phase, this activity was significantly decreased afterwards inducing lipogenesis.

Fatty acid composition in lipid fractions lengthwise the mycelium of Mortierella isabellina and lipid production by solid state fermentation.

This paper investigates the correlation between mycelial age and fatty acid biosynthesis. The correlation was investigated by analyzing the lipid composition lengthwise the mycelium of the oleaginous fungus Mortierella isabellina, a potential producer of gamma-linolenic acid (GLA). Young mycelia were rich in polar lipids (glycolipids plus sphingolipids and phospholipids), while neutral lipid content increased in aged mycelia.

Vulnerability to air pollution health effects.

Introduction: Ambient air pollution can have adverse effects on the health of exposed populations, but individuals or groups are not equally vulnerable, and pollution reduction benefits are likely to be unevenly distributed within a population. While the use of total-population risks is a valid approach for public health protection, it is increasingly recognized that more attention on vulnerable groups is necessary. This paper describes population vulnerability to the health effects of air pollutants using risk analysis concepts and based on available evidence.

Children's susceptibility to chemicals: a review by developmental stage.

Concerns about adequate protection of children's health from chemicals in the environment have created a need for research to identify how children's risks differ from adults'. A systematic review of factors that affect child sensitivity throughout development may be useful for research and practice in this area. We summarized available literature and other peer-reviewed information on factors that affect pharmacokinetics and exposure in an age-based developmental framework.

Cryptosporidiosis susceptibility and risk: a case study.

Regional estimates of cryptosporidiosis risks from drinking water exposure were developed and validated, accounting for AIDS status and age. We constructed a model with probability distributions and point estimates representing Cryptosporidium in tap water, tap water consumed per day (exposure characterization); dose response, illness given infection, prolonged illness given illness; and three conditional probabilities describing the likelihood of case detection by active surveillance (health effects characterization). The model predictions were combined with population data to derive expected case numbers and incidence rates per 100,000 population, by age and AIDS status, borough specific and for New York City overall in 2000 (risk characterization).

Defining susceptibility for microbial risk assessment: results of a workshop.

An interdisciplinary workshop was convened by the George Washington University in June 2001 to discuss how to incorporate new knowledge about susceptibility to microbial pathogens into risk assessment and management strategies. Experts from government, academic, and private sector organizations discussed definitions, methods, data needs, and issues related to susceptibility in microbial risk assessment. The participants agreed that modeling approaches need to account for the highly specific nature of host-pathogen relationships, and the wide variability of infectivity, immunity, disease transmission, and outcome rates within microbial species and strains.