Indicator Of Fungal Growth Research Articles

Quality assessment of goji fruits, cranberries, and raisins using selected markers

The aim of the study was to determine the antioxidant activity, total phenolic content, and total carotenoid content of dried fruit extracts prepared from goji fruits, cranberries, and raisins. Ergosterol content of samples—as a marker of fungal contamination—was measured by LC–MS/MS technique. For the goji fruit samples, fungal community-level physiological profiling and fungal isolate catabolic diversity were tested to evaluate more precisely their fungal contamination. The highest antioxidant activity and total phenolic content were determined for dried goji fruits. Simultaneously, the dried goji fruits were contaminated by ergosterol − 3.8 µg g−1 of dried fruit and the bulk goji fruits were contaminated by heat-resistant fungi. The study of fungal community as a fungal contamination marker of dried goji fruits was performed by a combination of the Biolog FF plates and traditional culture methods which is the first application of this composite analytical approach. Ergosterol content could be an indicator of fungal growth on dried fruits. The Biolog FF microplates can be used as a quick, easy, cheap, and effective method for the detection of heat-resistant fungi in dried fruits.

Discriminant analysis of volatile organic compounds of Fusarium oxysporum f. sp. cepae and Fusarium proliferatum isolates from onions as indicators of fungal growth

Basal rot is a common onion disease and is mainly caused by Fusarium oxysporum f. sp. cepae and Fusarium proliferatum. To study the possibility of using volatile organic compounds (VOCs) as biomarkers for these fungi, pathogenic isolates of F. oxysporum and F. proliferatum from onions were cultivated in onion medium and VOCs were measured by solid phase microextraction (SPME). Forty-two compounds were detected, and thirty of these compounds were highly related to fungal metabolic activity. Allyl mercaptan was specific to F. oxysporum isolate Fox006. Analysis of the VOCs showed significant differences between the two species and among different isolates within the same species. Sixteen of the VOCs showed were highly positively correlated with the fungal biomass estimated by real-time polymerase chain reaction (PCR). Ethanol, ethyl formate, ethyl acetate, 2-methyl-1-propanol, methyl thioacetate, n-propyl acetate and 3-methyl-1-butanol are volatile metabolites that were potential indicators of Fusarium growth on onions.

Extracted substrate colour as an indicator of fungal growth in solid state fermentation

Extracted substrate colour as an indicator of fungal growth in solid state fermentation

A quantitative method for fungal ligninolytic enzyme screening studies

AbstractScreening is conducted to select a fungus with desired characteristics intended for various applications, e.g. bioremediation and enzyme production. A qualitative method was used in this study for screening of fungal ligninolytic enzyme activities. The fungal ligninolytic activity was correlated with its growth from the screenings to identify a suitable fungus for solid substrate fermentation. Four strains of fungi, namely, Phanerochaete chrysosporium, Pycnoporus sanguineus, Phlebia radiata and Pleurotus sajor‐caju, were screened for their ligninolytic enzyme activities using guaiacol and remazol brilliant blue‐R (RBB‐R) as screening reagents. The screenings were conducted at both, the optimal growth temperature of each fungus and 35 °C. All the fungi, except P. radiata, showed positive guaiacol oxidation and RBB‐R decolourisation activities. On the basis of the results, P. sajor‐caju may be a suitable fungus for use in bioconversion of lignocellulose because it maintained guaiacol oxidation and RBB‐R decolourisation activities at 35 °C. Its halo‐to‐colony area ratios of guaiacol oxidation and RBB‐R decolourisation after 6 days were 7.0 and 2.7, respectively. In the subsequent growth study, the measured colony area was closely correlated with the dry fungal cell weight with a regression value (R2) of 0.971. Thus, the colony size could be used as an indicator of fungal growth if the screening media do not significantly slow the growth of fungus. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Fungal pretreatment of pine wood to reduce the emission of volatile organic compounds

Abstract Sterilized pine wood strands were treated with the ascomycete Ophiostoma piliferum (Cartapip 97™) in an attempt to reduce aldehyde emissions through degradation of aldehyde-forming precursors. Wooden boards were then produced from the treated strands by means of a laboratory press. VOC emissions of these boards were characterized and the concentrations of seven major substances were followed for a period of 28 days in Markes μ-CTE micro-chambers employing Tenax-TDAS/GC/MS analytics. Boards made from treated strands showed a highly significant (P<0.001) reduction in aldehyde emissions by 70% compared to the control boards, while differences in the monoterpene emissions were not significant (P>0.05). Wood extractives from treated and untreated strands were also analyzed by GC/MS after milling and acetone/water extraction. A marked decrease of C18 unsaturated fatty acids was detected in agreement with the reduction of aldehyde emissions, and the monosaccharides as indicators of fungal growth were depleted and stilbenes and lignans were partially degraded.

Detection of fungal infestations of wood by ion mobility spectrometry

During their growth on wood many fungi produce characteristic volatile organic compounds as secondary metabolites. These microbial volatile organic compounds (MVOCs) can be used as indicators of fungal growth even when such growth is concealed. In order to investigate the formation of these volatile metabolites on building materials, specimens of pine sapwood on agar media colonized by the dry-rot fungus Serpula lacrymans and a mixture of six moulds were examined. MVOCs from this fungal growth were studied over a period of up to half a year by ion mobility spectrometry (IMS) headspace analysis using a sensitive, portable IMS mini-device. The IMS headspace spectra from the growing fungal specimens obtained during this time span are differed from non-incubated wood specimens and indicate the presence of a mixture of MVOCs. The composition and amount of volatile metabolites of the fungi changed during cultivation. This was confirmed by a principal component analysis (PCA). Identification of different MVOCs in the headspace according to drift time and the mobility of ionized gaseous species in reference to GC-MS investigations were proposed. It was concluded that IMS can be used as a rapid and sensitive on-site method to indicate actively growing fungi concealed within wood.

Development of a GFP-Expressing Aspergillus flavus Strain to Study Fungal Invasion, Colonization, and Resistance in Cottonseed

Cotton bolls were inoculated with a green fluorescent protein (GFP)-expressing Aspergillus flavus (strain 70) to monitor fungal growth, mode of entry, colonization of cottonseeds, and production of aflatoxins. The GFP strain and the wild-type did not differ significantly in pathogen aggressiveness as indicated by similar reductions in inoculated locule weight. GFP fluorescence was at least 10 times higher than the blue green yellow fluorescence (BGYF) produced in response to infection by A. flavus. The GFP produced by the strain made it possible to identify and monitor specific plant tissues colonized by the fungus. For example, the inner seed coat and cotyledon were colonized by the fungus within 72 h of inoculation and the mode of entry was invariably through the porous chalazal cap in intact seeds. The amount of GFP fluorescence was shown to be an indicator of fungal growth, colonization and, to some extent, aflatoxin production. The A. flavus strain expressing GFP should be very useful for rapidly identifying cotton lines with enhanced resistance to A. flavus colonization developed through genetic engineering or traditional plant breeding. In addition, development of GFP expressing A. flavus strain provides an easy and rapid assay procedure for studying the ecology, etiology, and epidemiology of cotton boll rot caused by A. flavus resulting in aflatoxin contamination.

A microtiter plate procedure for evaluating fungal functional diversity

A method (FungiLog) was developed that allows a quantitative approach to examining aspects of fungal functional diversity. The BIOLOG microtiter plate method for measuring bacterial functional diversity was modified for use with fungal assemblages. Each BIOLOG plate contains 95 different carbon substrates. Eight different tetrazolium dyes were evaluated and dimethylthiazolyl-diphenyltetrazolium bromide (MTT) was chosen as the most suitable indicator of fungal growth. Procedures for inoculum preparation from a variety of substrates and inoculation into modified BIOLOG SF-N microplates were devised. By also plating out inoculum used to inoculate the FungiLog plates, taxonomic data can be obtained in conjunction with functional diversity. The FungiLog method was subsequently evaluated for detecting landscape patterns of fungal functional diversity using decaying lechuguilla (Agave lechuguilla) leaves placed along an elevational gradient in Big Bend National Park, Texas, in 5 vegetation zones. Sites ranged from a high elevation (2098 m) zone dominated by live oak (Quercus emoryi) and pinyon pine (Pinus cembroides) to a low land Chihuahuan Desert scrub (973 m). Ten, preweighed, 10-cm pieces of lechuguilla leaves were collected from each vegetation zone, 5 per transect, after 6 mo decomposition. FungiLog data were used to calculate two measures of fungal functional diversity, substrate richness and total activity. FungiLog patterns distinguished differences in total activity and substrate richness among the low elevational and the high elevational sites at this stage in the decomposition of lechuguilla leaves. Furthermore, litter decomposition was greater for sites with high fungal functional diversity.

Formation of zearalenone on wheat contaminated with Fusarium graminearum under controlled conditions

The contamination of cereals with field-growing Fusarium species can be a health hazard since Fusarium are known for their ability to produce mycotoxins like zearalenone (ZON) and deoxynivalenol (DON). For this study the formation of ZON was investigated under controlled growth conditions. Ergosterol, as an indicator of fungal growth, and ZON were analysed by HPLC with UV and fluorescence detection respectively. It is shown that ZON is synthesised in the late growth phase of the fungi, which is typical for secondary metabolites. Milling of contaminated wheat shows a reduced content of ZON in fractions of low ash content. Consequently the concentration of ZON in bran, which has a high ash content, was much higher.

Operational parameters for packed beds in solid-state cultivation

Packed bed cultivation systems have potential for widespread application in solid-state cultivation (SSC), but they are poorly characterized. The effects of particle size and substrate loading on the growth of Rhizopus oligosporus on sago-beads in packed bed bioreactors were investigated. Pressure drop and protein were monitored as indicators of fungal growth in cultivations performed in a large column (4.9 cm internal diameter and 60 cm height) and a system of small columns (4.2 cm internal diameter and 5.2 cm height). The differential pressure drop increased to a maximum between 34 and 44 h and then decreased again. The maximum differential pressure drop attained was greatest for the smallest particle size and for the lower substrate loadings. However, since the protein content continued to increase throughout the cultivation, pressure drop could not be used to monitor growth directly.

Einfluß von autoklavierung und oberflächendesinfektion von Weizen (Triticum aestivum) auf die Produktion von Ergosterin, ochratoxin A und Citrinin durch Penicillium verrucosum

Moist wheat was autoclaved, surface disinfected with NaOCl or left untreated. After inoculation with conidia of a toxigenic strain of Penicillium verrucosum kernels were stored at 10 and 4 degrees C. The production of ergosterol, a chemical indicator of fungal growth, was accelerated at both temperatures by each of the two treatments, compared to untreated wheat. The accumulation of ochratoxin A and citrinin was accelerated by each of the two treatments at 10 degrees C, whereas it was accelerated or retarded at 4 degrees C. It is concluded that the kinetics of growth and toxin production of Penicillium verrucosum during cold storage of wheat under real agricultural conditions cannot be predicted from in vitro studies with autoclaved or surface disinfected wheat.

Relationship of fungal chemical markers to normal and benodanil-affected growth and development of Puccinia hordei in leaves of barley

Normal growth and development of the rust Puccinia hordei on barley is accompanied by increases in amounts of the fungal compounds, mannan, ‘chitin’, arabitol and mannitol. Quantities of mannan, ‘chitin’ and arabitol are well linearly correlated to each other. However, mannitol increases in amount differently as infection progresses and is more closely, linearly related to fungal colony length. Amounts of arabitol, mannan and ‘chitin’ are more allied to sporulation than to mycelial growth. The fungicide benodanil, at a concentration of 11 g 1−1 active ingredient, effectively stops growth and development of P. hordei when applied on either day 3 or day 5 after inoculation. It also prevents any increase in the amounts of the fungal, biochemical markers, showing the sensitivity of these chemicals as indicators of fungal growth.