https://www.massey.ac.nz/%7Eychisti/Lipases.pdf

Production, purification, characterization, and applications of lipases.

Degradation of plant cell wall polysaccharides is of major importance in the food and feed, beverage, textile, and paper and pulp industries, as well as in several other industrial production processes. Enzymatic degradation of these polymers has received attention for many years and is becoming a more and more attractive alternative to chemical and mechanical processes. Over the past 15 years, much progress has been made in elucidating the structural characteristics of these polysaccharides and in characterizing the enzymes involved in their degradation and the genes of biotechnologically relevant microorganisms encoding these enzymes. The members of the fungal genus Aspergillus are commonly used for the production of polysaccharide-degrading enzymes. This genus produces a wide spectrum of cell wall-degrading enzymes, allowing not only complete degradation of the polysaccharides but also tailored modifications by using specific enzymes purified from these fungi. This review summarizes our current knowledge of the cell wall polysaccharide-degrading enzymes from aspergilli and the genes by which they are encoded.

Aspergillus Enzymes Involved in Degradation of Plant Cell Wall Polysaccharides

Publisher Summary This chapter discusses the ecological implications of mycorrhizal associations in natural ecosystems and the role of soil or environmental factors, mycorrhizal fungus characteristics or host plant properties. Mycorrhizal associations are regulated by features of the host plant and mycorrhizal fungus, as well as by soil conditions and environmental factors. Factors which can influence the occurrence and effectiveness of mycorrhizal associations include (1) root properties (2) edaphic or climatic factors (3) soil organisms, (4) soil disturbance, and (5) host-fungus compatibility. Several other complex ecological topics also discussed in the chapter include (1) mycorrhizal phenology , (2) factors responsible for varying degrees of mycorrhizal dependency in host plants, (3) the role of mycorrhizal hyphae in soil (4) nutrient competition involving mycorrhizal and non-mycorrhizal plants, and (5) mycorrhizal interactions involving pollution and other stresses, the rhizosphere, soil properties and allelopathy. Finally, the chapter also discusses the population ecology of mycorrhizal fungi and the influence of their associations on plant population ecology.

Mycorrhizas in Natural Ecosystems

There are several taxonomic systems available for identifying Fusarium species. The philosophy used in each taxonomic system is discussed as well as problems encountered in working with Fusarium species in culture. Fusarium species are toxigenic, and the mycotoxins produced by these organisms are often associated with animal and human diseases. The implications for the association of the carcinogens, fumonisins, produced by Fusarium moniliforme and other Fusarium species with human diseases are discussed. Foreign-body-associated fusarial infection such as keratitis in contact lens wearers, onychomycosis, skin infections, and disseminated multiorgan infections are discussed. Disseminated fusarial hyalohyphomycosis has emerged as a significant, usually fatal infection in the immunocompromised host. Successful outcome is determined by the degree of immunosuppression, the extent of the infection, and the presence of a removable focus such as an indwelling central venous catheter. These infections may be clinically suspected on the basis of a constellation of clinical and laboratory findings, which should lead to prompt therapy, probably with one of the newer antifungal agents. Perhaps the use of such agents or the use of colony-stimulating factors may improve the outcome of this devastating infection. However, until new approaches for treatment develop, effective preventive measures are urgently needed.

Taxonomy, biology, and clinical aspects of Fusarium species.

1 In laboratory microcosm experiments, co-occurring plant species were found to support very different rates of sporulation of arbuscular mycorrhizal (AM) fungi. These differences were not affected by the time of harvest, suggesting that they reflect host-dependent differences in fungal growth rates, rather than host-dependent timing of sporulation. 2 Spore counts in field soil and estimates from sorghum trap cultures showed that the association of AM fungi with particular host plants in the field was positively correlated with the sporulation rates observed on those hosts in the microcosm experiments. 3 The AM fungal species richness observed at the field site was high relative to estimates made in previous studies. 23 distinct species of AM fungi were found, seven of which have not been previously described. 4 The host-dependence of the relative growth rates of fungal populations may play an important role in the maintenance of fungal species diversity.

Host-Dependent Sporulation and Species Diversity of Arbuscular Mycorrhizal Fungi in a Mown Grassland

Spore density and mycorrhizal colonization were studied in four plant species within two sites in a lowland rain forest for a period of 17 months. Although the dominant VA endophyte and plant species examined in each site were different, the variation in spore numbers and mycorrhizal colonization in both sites showed a similar pattern. When spore numbers were high, percentage colonization was low, but as spore numbers began to decline the colonization increased. Highest spore numbers were recorded from Aug. to Oct. while most mycorrhizal colonization occurred from Dec. to March. To account for this variation, the possible interaction between the nutrient status of tropical soils and host plants with the life cycle of the VA endophytes is discussed.

Spore density and root colonization of vesicular-arbuscular mycorrhizas in tropical soil

Soybean (Glycine max cv. Mikiwashima) seedlings were inoculated with two tropical isolates of the vesicular-arbuscular mycorrhizal fungusGlomus clarum (Gc); isolateGcA was isolated from soils of low phosphate (P) and isolateGcB from soils of high P availability. In soil with low P,GcA was more efficient in increasing growth, nodulation and nitrogenase activity ofG. max thanGcB. Upon contact with the root surface, pre-infection hyphae ofGcA penetrated the root directly and rapidly colonised the cortical cells, while those ofGcB grew extensively on theroot surface with little host penetration. Mycorrhizal colonisation was higher in roots inoculated withGcA. Dual inoculation with the two isolates did not increase the effect of the single inoculation withGcA. In soils of high P status, both isolates formed pre-infection hyphae with few entry ooints and percentage mycorrhizal root colonisation was consequently low. The variation in efficacy of the isolates emphasizes the significance of evaluating host specificity when selecting efficient VA mycorrhizae strains for field studies.

Differential response in growth and mycorrhizal colonisation of soybean to inoculation with two isolates ofGlomus clarum in soils of different P availability

Methode simple et peu couteuse pour detecter l'activite cellulolytique sur plaque de gelose en utilisant un melange d'acide chlorhydrique et d'une solution iodee

A simple method for screening cellulolytic fungi

The influence of extracellular conidial matrix on germinability was investigated using a tropical isolate of Colletotrichum capsici . Decreasing spore density and the amount of accompanying matrix increased germinability of freshly gathered spores, especially those from C. capsici the inhibitory or retardatory role of the matrix should be considered in the context of mass survival previous to splash-dispersal.

Influence of spore density and extracellular conidial matrix on spore germination in Colletotrichum capsici

A survey of Fusarium in the cultivated and uncultivated soils of Singapore showed the presence ofF. episphaeria, F. oxysporum, F. roseum andF. solani. The total population of Fusarium was small in uncultivated soils, some of which did not show any Fusarium, but much larger in cultivated soils.F. solani was recovered in highest numbers per g of soil, whileF. episphaeria was lowest, and rarely found in uncultivated soils.

G. Lim

Papers

Spore density and root colonization of vesicular-arbuscular mycorrhizas in tropical soil

Differential response in growth and mycorrhizal colonisation of soybean to inoculation with two isolates ofGlomus clarum in soils of different P availability

A simple method for screening cellulolytic fungi

Influence of spore density and extracellular conidial matrix on spore germination in Colletotrichum capsici

Fusarium in Singapore soils