Assessment Of Fungal Growth Research Articles

Studies on Aspergillus flavus on Tiger Nut (Cyperus esculentus) Incubated at Different Regimes of Light and Two Temperatures

An experiment was carried out to ascertain the effect of light regimes (continuous day light, continuous darkness and alternating day light and darkness) on the growth of A. flavus on tiger nut at temperature of 28oC and 30oC. The experiment was a 2 x 3 factorial laid out in a completely randomized design (CRD) replicated 10 times. A. flavus was isolated from naturally infected tiger nuts obtained from different sellers at Delta Park, Abuja Park and Choba campus, University of Port Harcourt, Rivers State, Nigeria. The isolation and sub-culturing were done using Malt Extract Agar (MEA). A tiger nut-based-medium (15ml/Plate) was centrally inoculated with 6-day-old inoculums of A. flavus and incubated appropriately. Assessment of fungal growth was done daily for 10 days and mycelia diameter and mycelia growth rate obtained from the data. Result from the statistical analysis showed that the effect of light regime and temperature on the mycelia diameter of A. flavus was highly significant (P<0.001) and the interaction between light regime and temperature was also significant (P<0.0.01). Growth rate also showed significant (P<0.001) main effect of temperature and light regime and the light regimes x temperature was also significant (P=0.03). The highest mycelia growth rate and mycelia diameter occurred in continuous day light, followed by continuous darkness and finally alternating day light and darkness, with all higher at 30oC. Thus, storage of tiger nut under continuous day light and/or at temperature 28oC and above should be discouraged, in order to reduce microbial spoilage caused by Aspergillus flavus.

Metabolic and morphostructural plasticity of environmental and animal strains of Nannizzia gypsea.

Nannizzia gypsea is a geophylic agent of human and animal dermatophytosis. This study compares the metabolic and morphostructural plasticity of N. gypsea strains isolated from moss, sand, and a dog. The in vitro metabolic plasticity included the detection of extracellular enzymes, thermotolerance, resistance to oxidative stress, and assessment of fungal growth. Structural plasticity studies included cell surface hydrophobicity, electronegativity, and size of macroconidia. Virulence was assessed on Tenebrio mollitor model. The strains showed low thermotolerance, susceptibility to oxidative stress, and were producers of keratinase, lipase and catalase. N. gypsea strains were unable to produce hemolysin, esterase, and phospholipase although they were able to grow with different carbon sources. The electronegative properties of the surface did not vary between the strains under study. The knowledge about N. gypsea metabolic and morphostructural plasticity could be crucial for the development of therapeutic strategies and control of dermatophytosis.

Screening of Fungal Strains for Cellulolytic and Xylanolytic Activities Production and Evaluation of Brewers’ Spent Grain as Substrate for Enzyme Production by Selected Fungi

Brewer’s spent grain (BSG), the solid residue of beer production, is attracting significant attention as raw material for the production of added value substances, since until recently it was mainly used as animal feed or deposited in landfills, causing serious environmental problems. Therefore, this work aimed at developing a bioprocess using BSG as a substrate for the production of cellulases and xylanases for waste saccharification and bioenergy production. Different fungi were analyzed for their cellulolytic and xylanolytic abilities, through a first screening on solid media by assessment of fungal growth and enzyme production on agar containing carboxylmethylcellulose or xylan as the sole carbon source, respectively. The best cellulase and xylanase producers were subjected to quantitative evaluation of enzyme production in liquid cultures. Aspergillus niger LPB-334 was selected for its ability to produce cellulase and xylanase at high levels and it was cultivated on BSG by solid state fermentation. The cellulase production reached a maximum of 118.04 ± 8.4 U/g of dry substrate after 10 days of fermentation, while a maximum xylanase production of 1315.15 ± 37.5 U/g of dry substrate was reached after 4 days. Preliminary characterization of cellulase and xylanase activities and identification of the enzymes responsible were carried out.

Assessment of Fungal Growth at Hemodialysis and Peritoneal Dialysis Unit in Hawler Teaching Hospital

Dialysis is used when the patient's kidneys can no longer perform their functions normally; it is a treatment that performs the functions of natural kidneys. Most patients begin dialysis when their kidneys have lost 85-90% of their ability to work naturally and they have to depend on dialysis for the rest of their lives, is called end –stage renal disease (ESRD). Infection in patients with end stage renal disease (ESRD) is usually treated with hemodialysis (HD) or peritoneal dialysis (PD). End stage renal disease a major cause of morbidity and mortality, in order to assess the fungal growth at hemodialysis and peritoneal dialysis unit a descriptive study was conducted at hemodialysis and peritoneal dialysis units in Hawler teaching hospital, from 15th of January to the end of May 2017;the study also includes the access sites and peritoneal catheter site. Factors that affected the access site among dialysis patient in the hospital. Sample of 63 patients, who were attending to the dialysis unit at time of the data collection, had been taken; in addition to that swab samples had been gathered from access site and peritoneal catheter site. The results of the study revealed that the fungal growth was positive at dialysis access sites, where the total percentage was 84.1% and that of peritoneal catheter site was 15.85%. In these unites, different types of filamentous fungi and yeasts had been successfully isolated.

Effects of environmental conditions on growth ofAspergillus nigerandPenicillium expansum

The effect of water activity (0.85–0.99 a w ) and temperature (20–35 °C) on growth of two potentially toxigenic moulds, Aspergillus niger and Penicillium expansum, were studied. On the basis of the measured colony diameter ComBase DMFit program was used to estimate the lag phase and growth rate. Similar results may provide basis for the risk assessment of fungal growth (and also for the possible mycotoxin contamination) in food and feed plants in the vegetation season due to the climate change (global warming), and also during unfavourable storage conditions.

Colonization of living skin equivalents by

Initial colonization events and yeast–hyphal transformation by Malassezia furfur were observed using living skin equivalent (LSE) models for growth. Yeast cells were inoculated onto the LSEs which were incubated in CO2-independent media at 37 °C for variable lengths of time. Assessment of fungal growth and invasion was by light- and scanning electron microscopy (SEM). Viability counts of M. furfur were determined by a method of washing and serial dilution. Yeast cells had retained their viability and increased in number ≈twofold over a 4-day period of incubation. Yeast-to-hyphal transition was not achieved in this model. Random destruction of the uppermost layers of the stratum corneum was observed in the presence of M. furfur. LSEs therefore appear to be a promising model for mechanisms of growth of cutaneous organisms.

Colonization of living skin equivalents byMalassezia furfur

Initial colonization events and yeast-hyphal transformation by Malassezia furfur were observed using living skin equivalent (LSE) models for growth. Yeast cells were inoculated onto the LSEs which were incubated in CO2-independent media at 37 degreesC for variable lengths of time. Assessment of fungal growth and invasion was by light- and scanning electron microscopy (SEM). Viability counts of M. furfur were determined by a method of washing and serial dilution. Yeast cells had retained their viability and increased in number approximately twofold over a 4-day period of incubation. Yeast-to-hyphal transition was not achieved in this model. Random destruction of the uppermost layers of the stratum corneum was observed in the presence of M. furfur. LSEs therefore appear to be a promising model for mechanisms of growth of cutaneous organisms.

Fungal polygalacturonase activity reflects susceptibility of carnation cultivars to fusarium wilt

Carnation cultivars with different levels of partial resistance were inoculated with race 2 of Fusarium oxysporum f.sp. dianthi and monitored for accumulation of host phytoalexins, fungal escape from compartmentalization, production of fungal pectin-degrading enzymes and development of external disease symptoms. Accumulation of phytoalexins, assessed after 10 days in the first 5 cm above the inoculation site, was weakly (methoxydianthramide S) or not (hydroxydianthalexin B) correlated with resistance levels after 12 weeks. Fungal escape from compartmentalization, assessed after 3 weeks as percentages colonized plants at 8 cm above the inoculation site, was highly correlated with expression of susceptibility after 12 weeks. Polygalacturonase (PG) activity, assessed after 4 weeks in the first 5 cm above the inoculation site, was highly correlated to final disease development. Linear increases in disease severity were accompanied by quadratic increases in PG activity. In contrast to water-treated plants, that lacked any PG activity, inoculated plants contained two main groups of fungal PGs, the dominant forms of which had estimated pI values of 7.0 and minimally 9.5, respectively. Compared to those of the first group, enzymes of the second group were produced only in trace amounts in liquid media containing pectin or polygalacturonate as sole source of carbon. On these media, the fungus also produced a pectin methyl esterase (PME) with an estimated pI of 9.3. Besides PMEs of host origin, inoculated plants of susceptible cultivars contained the fungal PME while no more than traces were found in resistant ones.Assessment of phytoalexin production by the host during defense responses cannot replace monitoring of external symptoms as a resistance test. Assessment of fungal growth, whether by reisolations above the compartmentalization area or by measurement of PG activity, provides a both rapid and reliable prediction of disease development.

Assessment of fungal growth in liquid cultures and bioassay of toxic products

This article outlines a procedure for the assessment of fungal growth under different cultural conditions; together with the demonstration of the toxic nature of the exudates released from a fungal pathogen during growth in culture, using a simple bioassay.