Aspergillus water requirements

Aspergillus sp. are common allergens (hay fever, asthma, pneumonitis, etc.). Water requirement on a substrate depends on species, and typically varies between 71 and 94%. This is often described as Aw index, that is, available water index. Aw refers to a range of minimum water requirements, and is expressed as Aw = ERH/100 (air), where ERH is equilibrium relative humidity. Eor Aspergillus species Aw =... 

Many process mixtures, notably fermentations, require sample preconcentration, microdialysis, microfiltration, or ultrafiltration prior to analysis. A capillary mixer has been used as a sample preparation and enrichment technique in microchromatography of polycyclic aromatic hydrocarbons in water.8 Microdialysis to remove protein has been coupled to reversed phase chromatography to follow the pharmacokinetics of the metabolism of acetaminophen into acetaminophen-4-O-sulfate and acetaminophen-4-O-glucu-ronide.9 On-line ultrafiltration was used in a process monitor for Aspergillus niger fermentation.10... 

Eor xylanases the source of the enzyme is important, fungal xylanases from Aspergillus spp. are generally very useful for bread making whereas for cookies Trichoderma spp. xylanases are required because of the differing requirements for water release. 

Enzymic interesterification is a recent development of considerable promise. Its advantage over the more conventional procedures lies in the additional control of product composition. The lipase, coated on to a support material (kieselguhr, hydroxylapatite, alumina) in the presence of a little water, supports interesterification at about 40 °C and usually requires 16-70 h for complete reaction but can be shorter depending on catalyst activity. The process may be operated in a batch or continuous manner. The substrate is a natural oil or fat to which may be added a second oil or fat and/or a particular fatty acid or fatty acid mixture. Three types of enzyme are available. One type (from Candida cylindricae, Coryne-bacterium acnes or Staphylococcus aureus) is nonspecific and leads to complete randomization of all acids at all positions. The product is the same as that obtained from the ordinary catalytic process. A second type of lipase (from Aspergillus niger, Mucor favanicus, Rhizopus arrhizus, / . delemar... 

---