Influence of the intrinsic characteristics of mortars on their biofouling by pigmented organisms: Comparison between laboratory and field-scale experiments

Biodeterioration of mortars by the photosynthetic microorganisms is affected by their intrinsic properties such as porosity, roughness and surface pH. The influence of these parameters was examined using an accelerated fouling test in laboratory and a natural fouling test in the real-world (in situ). Based on color measurement and image analysis, the impact of each intrinsic parameter was evaluated. The results differed from a scale to the other one. No influence of porosity was measured on the algal colonization rate in the laboratory test whereas, a high porosity seemed to increase slightly the bioreceptivity of the mortars exposed outdoor. The roughness, in both tests, promoted the microbial colonization. However, the discrimination of roughness grades was better in the laboratory test than in the in situ one. The surface pH influenced remarkably on the accelerated biofouling test but not on the in situ one. These dissimilarities resulted from the differences in experimental configurations of the two tests.     

Laboratory grown subaerial biofilms on granite: application to the study of bioreceptivity

Simulated environmental colonisation of granite was induced under laboratory conditions in order to develop an experimental protocol for studying bioreceptivity. The experimental set-up proved suitable for producing subaerial biofilms by inoculating granite blocks with planktonic multi-species phototrophic cultures derived from natural biofilms. The ability of four different cultures to form biofilms was monitored over a three-month growth period via colour measurements, quantification of photosynthetic pigments and EPS, and CLSM observations. One of the cultures under study, which comprised several taxa including Bryophyta, Charophyta, Chlorophyta and Cyanobacteria, was particularly suitable as an inoculum, mainly because of its microbial richness, its rapid adaptability to the substratum and its high colonisation capacity. The use of this culture as an inoculum in the proposed experimental set-up to produce subaerial biofilms under laboratory conditions will contribute to standardising the protocols involved, thus enabling more objective assessment of the bioreceptivity of granite in further experiments.     

Accelerated testing of mold growth on traditional and recycled book paper

The growth of molds on paper containing cellulose is a frequent occurrence when the level of relative air humidity is high or when books become wet due to water leaks in libraries. The aim of this study is to differentiate the bioreceptivity of different types of book paper for different fungi. Laboratory tests were performed with strains of Aspergillus niger, Cladosporium sp., Chaetomium globosum and Trichoderma harzianum isolated from books. Four paper types were evaluated: couché, Pólen (offset), recycled and a reference paper containing only cellulose. The tests were carried out in chambers with relative air humidity of 95% and 100%. Mold growth was greatest in the tests at 100% relative humidity. Results of stereoscopic microscopy observation showed that Cladosporium sp. grew in 74% of these samples, A. niger in 75%, T. harzianum in 72% and C. globosum in 60%. In the chambers with 95% air humidity Cladosporium sp. grew in only 9% of the samples, A. niger in 1%, T. harzianum in 3% and C. globosum did not grow in any sample. The most bioreceptive paper was couché and the least receptive was recycled paper. The composition of the recycled paper, however, varies depending on the types of waste materials used to make it.     

Accelerated laboratory test to study fungal biodeterioration of cementitious matrix

The present study aimed to develop an accelerated laboratory test to study the biodeteriorative effect of different fungal strains to a cementitious matrix. The test developed in this study permits to obtain a rapid fungal development on cement specimens. Three months of experiments only are needed to obtain first results, which is rather shorter than other test developed to date to study fungal biodeterioration. Results are mainly related to aesthetical biodeterioration. Results show that in these experimental conditions, fungal growth occurs since the first week of incubation. Stereomicroscopy observations showed that microbial growth was noticed only on the surface of specimens, while PAS staining revealed the real extent of microbial growth on and within the matrix as later confirmed by SEM observations of cross section showing the penetration of hyphae inside the matrix. Test can be used with short time of incubation, to test and to compare bioreceptivity of cement-based materials; and several months of incubation should allow the study of mechanisms involved in biodeterioration.     

Xerotolerant Cladosporium sphaerospermum Are Predominant on Indoor Surfaces Compared to Other Cladosporium Species

Indoor fungi are a major cause of cosmetic and structural damage of buildings worldwide and prolonged exposure of these fungi poses a health risk. Aspergillus, Penicillium and Cladosporium species are the most predominant fungi in indoor environments. Cladosporium species predominate under ambient conditions. A total of 123 Cladosporium isolates originating from indoor air and indoor surfaces of archives, industrial factories, laboratories, and other buildings from four continents were identified by sequencing the internal transcribed spacer (ITS), and a part of the translation elongation factor 1α gene (TEF) and actin gene (ACT). Species from the Cladosporium sphaerospermum species complex were most predominant representing 44.7% of all isolates, while the Cladosporium cladosporioides and Cladosporium herbarum species complexes represented 33.3% and 22.0%, respectively. The contribution of the C. sphaerospermum species complex was 23.1% and 58.2% in the indoor air and isolates from indoor surfaces, respectively. Isolates from this species complex showed growth at lower water activity (≥ 0.82) when compared to species from the C. cladosporioides and C. herbarum species complexes (≥ 0.85). Together, these data indicate that xerotolerance provide the C. sphaerospermum species complex advantage in colonizing indoor surfaces. As a consequence, C. sphaerospermum are proposed to be the most predominant fungus at these locations under ambient conditions. Findings are discussed in relation to the specificity of allergy test, as the current species of Cladosporium used to develop these tests are not the predominant indoor species.     

Prediction of Toxigenic Fungal Growth in Buildings by Using a Novel Modelling System

There is growing concern about the adverse effects of fungal bioaerosols on the occupants of damp dwellings. Based on an extensive analysis of previously published data and on experiments carried out within this study, critical limits for the growth of the indoor fungi Eurotium herbariorum, Aspergillus versicolor, and Stachybotrys chartarum were mathematically described in terms of growth limit curves (isopleths) which define the minimum combination of temperature (T) and relative humidity (RH) at which growth will occur. Each growth limit curve was generated from a series of data points on a T-RH plot and mathematically fitted by using a third-order polynomial equation of the form RH = a₃T³ + a₂T² + a₁T + a₀. This fungal growth prediction model was incorporated within the ESP-r (Environmental Systems Performance [r stands for “research”]) computer-based program for transient simulation of the energy and environmental performance of buildings. For any specified location, the ESP-r system is able to predict the time series evolution of local surface temperature and relative humidity, taking explicit account of constructional moisture flow, moisture generation sources, and air movement. This allows the predicted local conditions to be superimposed directly onto fungal growth curves. The concentration of plotted points relative to the curves allows an assessment of the risk of fungal growth. The system’s predictive capability was tested via laboratory experiments and by comparison with monitored data from a fungus-contaminated house.     

Cladosporium sphaerospermum as a new plant growth-promoting endophyte from the roots of Glycine max (L.) Merr.

Endophytic fungi are plant symbionts that produce a variety of beneficial metabolites for plant growth and protection against herbivory and pathogens. Fourteen fungal samples were isolated from the roots of soybean cultivar Daemangkong and screened on waito-c rice for their plant growth-promoting capacity. Twelve of the fungal isolates promoted plant growth, while two inhibited it. The fungal isolate DK-1-1 induced maximum plant growth in both waito-c rice and soybean. The plant growth promotion capacity of DK-1-1 was higher than the wild type Gibberella fujikuroi. Gibberellin (GA) analysis of culture filtrate of DK-1-1 showed the presence of higher amounts of bioactive GA₃, GA₄, and GA₇ (6.62, 2.1 and 1.26 ng/mL, respectively) along with physiologically inactive GA₅, GA₁₅, GA₁₉, and GA₂₄. Phylogenetic analysis of 18S rDNA sequence identified the fungal isolate as a new strain of Cladosporium sphaerospermum. Gibberellin production and plant growth-promoting ability of genus Cladosporium are reported for the first time in the present study. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Comparative root colonisation of strawberry cultivars Camarosa and Festival by Fusarium oxysporum f. sp. fragariae

Background and aims

Strawberry (Fragaria x ananassa) is a high-value crop worldwide. Fusarium oxysporum f. sp. fragariae causes rapid wilting and death of strawberry plants and severe economic losses worldwide. To date, no studies have been conducted to determine colonisation of either susceptible or resistant strawberry plants by F. oxysporum f. sp. fragariae, or whether plant colonisation by F. oxysporum f. sp. fragariae differs between susceptible and resistant cultivars.

Methods

Colonisation of strawberry plants by a pathogenic isolate of F. oxysporum f. sp. fragariae was examined both on the root surface and within root tissue of one resistant cv. Festival and one susceptible cv. Camarosa using light and scanning electron microscopy from 4?h to 7?d post inoculation (pi).

Results

Resistant cv. Festival significantly impeded the spore germination and penetration from 4 to 12 hpi and subsequent growth and colonisation by this pathogen until 7 dpi compared with susceptible cv. Camarosa. At 7 dpi, fungal colonisation in resistant cv. Festival remained mainly confined to the epidermal layer of the root, while in susceptible cv. Camarosa, hyphae not only had heavily colonised the cortical tissue throughout but had also colonised vascular tissues.

Conclusions

This study demonstrates for the first time that resistance of a strawberry cultivar to F. oxysporum f. sp. fragariae is a result of impedance of pathogen growth and colonisation both on the plant surface and within host tissues. Resistance mechanisms identified in this study will be of high value for breeding programmes in developing new disease-resistant cultivars to manage this serious strawberry disorder.     

The diversity, antimicrobial and anticancer activity of endophytic fungi associated with the medicinal plant Stryphnodendron adstringens (Mart.) Coville (Fabaceae) from the Brazilian savannah

The diversity and biological activities of the endophytic fungi associated with the Brazilian medicinal plant Stryphnodendron adstringens were studied. A total of 320 fungal isolates were obtained, and 66 phylotypes comprising 25 genera were identified. The fungal community of S. adstringens displayed high richness, diversity and low dominance indices. The most abundant phylotypes were closely related to Diaporthe phaseolorum, Guignardia camelliae, and Preussia pseudominima. Sixteen fungal extracts displayed biological activities when screened against bacteria, fungi, cancer cell lines, and amastigote forms of Leishmania amazonensis. The extract of phylotype Nigrospora cf. oryzae exhibited a selective antifungal activity and inhibited the growth of Candida albicans and Cladosporium sphaerospermum. The extracts of Diaporthe cf. phaseolorum and Xylaria sp. phylotypes displayed anticancer activities. Our results indicate that the endophytes associate with this medicinal plant may be a source for novel drugs.     

Relationship between Fungal Colonisation of the Respiratory Tract in Lung Transplant Recipients and Fungal Contamination of the Hospital Environment

Background

Aspergillus colonisation is frequently reported after lung transplantation. The question of whether aspergillus colonisation is related to the hospital environment is crucial to prevention.

Method

To elucidate this question, a prospective study of aspergillus colonisation after lung transplantation, along with a mycological survey of the patient environment, was performed.

Results

Forty-four consecutive patients were included from the day of lung transplantation and then examined weekly for aspergillus colonisation until hospital discharge. Environmental fungal contamination of each patient was followed weekly via air and surface sampling. Twelve patients (27%) had transient aspergillus colonisation, occurring 1–13 weeks after lung transplantation, without associated manifestation of aspergillosis. Responsible Aspergillus species were A. fumigatus (6), A. niger (3), A. sydowii (1), A. calidoustus (1) and Aspergillus sp. (1). In the environment, contamination by Penicillium and Aspergillus was predominant. Multivariate analysis showed a significant association between occurrence of aspergillus colonisation and fungal contamination of the patient’s room, either by Aspergillus spp. in the air or by A.fumigatus on the floor. Related clinical and environmental isolates were genotyped in 9 cases of aspergillus colonisation. For A. fumigatus (4 cases), two identical microsatellite profiles were found between clinical and environmental isolates collected on distant dates or locations. For other Aspergillus species, isolates were different in 2 cases; in 3 cases of aspergillus colonisation by A. sydowii, A. niger and A. calidoustus, similarity between clinical and environmental internal transcribed spacer and tubulin sequences was >99%.

Conclusion

Taken together, these results support the hypothesis of environmental risk of hospital acquisition of aspergillus colonisation in lung transplant recipients.     

Mycorrhizal colonisation in plants from intermittent aquatic habitats

Several plant species with amphibious characteristics from intermittent aquatic habitats were examined for colonisation with arbuscular mycorrhizal fungi (AM), dark septate endophytes (DSE) and the ratio of aerenchyma in root tissue. We studied submerged specimens of Alisma plantago-aquatica, Mentha aquatica, Myosotis scorpioides, Oenanthe fistulosa, Gratiola officinalis, Glyceria fluitans, Sium latifolium and Teucrium scordium. In the first four, we also examined the emerged growth forms, which were grown under experimental conditions. Roots of all species were mycorrhizal and showed AM and DSE colonisation. The results suggest that AM colonisation may also be abundant in plants of aquatic environment. Arbuscules were not found in submerged specimens of M. aquatica, O. fistulosa and S. latifolium. The AM colonisation was generally higher in emerged specimens as compared to submerged ones. The aerenchyma ratio in root cross-sections ranged from 10 to 50% and in most cases did not differ between submerged and emerged specimens. No clear relationship between AM colonisation and aerenchyma ratio was recognized, while a positive correlation between AM and plant available phosphorous was established.     

Gut Microbiota Patterns Associated with Colonization of Different Clostridium difficile Ribotypes

C. difficile infection is associated with disturbed gut microbiota and changes in relative frequencies and abundance of individual bacterial taxons have been described. In this study we have analysed bacterial, fungal and archaeal microbiota by denaturing high pressure liquid chromatography (DHPLC) and with machine learning methods in 208 faecal samples from healthy volunteers and in routine samples with requested C. difficile testing. The latter were further divided according to stool consistency, C. difficile presence or absence and C. difficile ribotype (027 or non-027). Lower microbiota diversity was a common trait of all routine samples and not necessarily connected only to C. difficile colonisation. Differences between the healthy donors and C. difficile positive routine samples were detected in bacterial, fungal and archaeal components. Bifidobacterium longum was the single most important species associated with C. difficile negative samples. However, by machine learning approaches we have identified patterns of microbiota composition predictive for C. difficile colonization. Those patterns also differed between samples with C. difficile ribotype 027 and other C. difficile ribotypes. The results indicate that not only the presence of a single species/group is important but that certain combinations of gut microbes are associated with C. difficile carriage and that some ribotypes (027) might be associated with more disturbed microbiota than the others.     

A study of the fungi occurring on 15th century frescoes in Florence,Italy

The role of fungi in the biodeterioration of frescoes has been investigated by means of transparent adhesive tape and by swabbing the surface of selected areas as well as by a study of the materials used in restoration. In the Ognissanti church at Florence a large fungal population was found on two 15th century frescoes, one by Botticelli of ‘St Augustine’ and the other by Ghirlandaio of ‘St Jerome’. Twenty-three species were identified, 15 on the Botticelli where the majority of the colony forming units (cfu) were Penicillium brevi-compactum Dierckx (61%) and P. purpurogenum Stoll (18%), and 13 on the Ghirlandaio where Aspergillus versicolor (Vuill.) Tiraboschi was the most common (74%), together with Cladosporium sphaerospermum Penz. (22%). The materials often used in restoration namely calcium caseinate, masonite and animal glue were tested and found to be suitable substrates for species of Aspergillus and Penicillium but not for Cladosporium cladosporioides and C. sphaerospermum.     

Real-time PCR assay for detection and differentiation of Coccidioides immitis and Coccidioides posadasii from culture and clinical specimens

Coccidioidomycosis (Valley fever) is a pulmonary and systemic fungal disease with increasing incidence and expanding endemic areas. The differentiation of etiologic agents Coccidioides immitis and C. posadasii remains problematic in the clinical laboratories as conventional PCR and satellite typing schemes are not facile. Therefore, we developed Cy5- and FAM-labeled TaqMan-probes for duplex real-time PCR assay for rapid differentiation of C. immitis and C. posadasii from culture and clinical specimens. The RRA2 gene encoding proline-rich antigen 2, specific for Coccidioides genus, was the source for the first set of primers and probe. Coccidioides immitis contig 2.2 (GenBank: AAEC02000002.1) was used to design the second set of primers and probe. The second primers/probe did not amplify the corresponding C. posadasii DNA, because of an 86-bp deletion in the contig. The assay was highly sensitive with limit of detection of 0.1 pg gDNA/PCR reaction, which was equivalent to approximately ten genome copies of C. immitis or C. posadasii. The assay was highly specific with no cross-reactivity to the wide range of fungal and bacterial pathogens. Retrospective analysis of fungal isolates and primary specimens submitted from 1995 to 2020 confirmed 168 isolates and four primary specimens as C. posadasii and 30 isolates as C. immitis from human coccidioidomycosis cases, while all eight primary samples from two animals (rhesus monkey and rhinoceros) were confirmed as C. posadasii. A preliminary analysis of cerebrospinal fluid (CSF) and pleural fluid samples showed positive correlation between serology tests and real-time PCR for two of the 15 samples. The Coccidioides spp. duplex real-time PCR will allow rapid differentiation of C. immitis and C. posadasii from clinical specimens and further augment the treatment and surveillance of coccidioidomycosis.     

Spatial associations among palatable and unpalatable macroalgae: A test of associational resistance with a herbivorous amphipod

Associational resistance is the process by which plants may gain protection from spatial associations with neighbouring plants. We tested whether association with an unpalatable alga, Dictyopteris acrostichoides, affects the abundance and colonisation behaviour of the herbivorous amphipod Peramphithoe parmerong on its preferred host alga Sargassum linearifolium. Despite predictions, natural densities on S. linearifolium when surrounded by D. acrostichoides were higher than on isolated individuals of S. linearifolium. Colonisation experiments in the laboratory and the field tested the hypotheses that the observed variation in field abundance with algal neighbourhood was due to variation in the size of habitat patches, physical obstruction of host finding by D. acrostichoides and variation in the relative abundance of S. linearifolium and D. acrostichoides. None of these possible mechanisms was found to significantly alter rates of amphipod colonisation on the scales of individuals selecting among algal pieces in the laboratory or among habitat patches in the field. The failure of colonisation processes to explain observed variation in natural amphipod densities suggests that post-colonisation processes such as survival or emigration may vary with the spatial associations among algae.     

Microfungal Contaminants on Mobile Phones of Health Services Vocational School Students in Marmaris,Turkey

In this study, it was aimed to determine microfungi on mobile phones. Totally, 50 mobile phones were used belonging to Health Services Vocational School students. The samples were taken by swabbing the screen and keys of mobile phones using moistened sterile swab sticks. A total of 24 different microfungal species were obtained belonging to Alternaria, Aspergillus, Cladosporium, Geotrichum, Penicillium, Phoma, Rhinocladiella, Scopulariopsis, Trichoderma, and Trichophyton genera. The genera of microfungi most abundant in terms of the number of species on the mobile phones were Aspergillus, Cladosporium, and Penicillium. Numerically, Cladosporium was found as the most abundant on the mobile phones. Cladosporium herbarum colonies were highest in number, followed by Cladosporium sphaerospermum, and Penicillium verrucosum var. cyclopium. When percentages of each species present on the mobile phones were considered, C. herbarum and C. sphaerospermum were the most common. There was a great similarity between the dominant microfungi isolated from mobile phones and dominant microfungi obtained from studies of atmospheric microfungi in Turkey.     

Comparison of real-time PCR and microscopy to evaluate sclerotial colonisation by a biocontrol fungus

The biocontrol agent Trichoderma harzianum colonises sclerotia of the plant pathogenic fungus Sclerotinia sclerotiorum. Plating of sclerotia typically has been used to determine the incidence of mycoparasitism, but does not quantify the extent to which individual sclerotia are colonised. We developed a specific PCR primer/probe set for the green fluorescent protein (GFP)-transformant T. harzianum ThzID1-M3, which exhibited high precision and reproducibility. Quantitative real-time PCR was evaluated along with epifluorescence microscopy and image analysis to investigate dynamics of colonisation of sclerotia in non-sterile soil. Amounts of ThzID1-M3 DNA and S. sclerotiorum DNA from entire individual sclerotia were quantified using real-time PCR. Epifluorescence micrographs were captured from sclerotial thin-section samples, and GFP fluorescence from these was quantified using computer image analysis in order to estimate colonisation on a per-sclerotium basis. As determined by either method, ThzID1-M3 colonised sclerotia in soil, and both methods quantified colonisation dynamics over time. In a separate experiment, colonisation of sclerotia on agar plates was observed using confocal laser scanning microscopy to view the GFP-fluorescing hyphae of ThzID1-M3. This method, while highly labour-intensive, provided high spatial resolution of colonisation dynamics. Thus, each method has advantages: microscopy combined with image analysis can provide useful information on the spatial and temporal dynamics of colonisation, while real-time PCR can provide a more precise assessment of the extent of sclerotial colonisation over time and can more easily be used to sample entire sclerotia.     

Fungal control of early-stage bacterial community development in decomposing wood

The earliest stages of bacterial colonisation of wood have received little attention, particularly with respect to how the colonisation process may be affected by the presence of wood-decay fungi. This study used 16s rRNA gene sequencing to examine the bacterial community in wood that had been incubated in the field for 14 or 84 d, either in wood uncolonised by fungi or pre-colonised by Vuilleminia comedens, Trametes versicolor or Hypholoma fasciculare. All three fungal species significantly delayed bacterial colonisation of the wood. V. comedens and H. fasciculare also reduced bacterial OTU richness and altered bacterial community composition, increasing the relative abundance of Burkholderiales and reducing the proportion of Enterobacteriaceae and Bacteroidetes. Wood that had not been pre-colonised showed seasonal differences between autumn and spring: bacterial richness increased between 14 d and 84 d in the spring, but not in the autumn. Community composition at 84 d in spring was also different to the other time points, with reduced dominance of Gamma-proteobacteria. Archaea were also detected in nearly a third of samples, but with no apparent pattern, and always at low abundances.     

Air-borne fungi at Doha, Qatar

Thirty-five genera and 73 species, were identifiedfrom 312 daily exposures set up during theperiod March 1997–March 1998. The total fungalcatch exhibited two peaks in July and December1997 and a trough in February 1998. Cladosporium (6 spp. 40.1% of total fungi),Alternaria (4 spp., 21%) andUlocladium (4 spp., 9.2%) were the maincomponents of air-borne fungi, and thecommonest species were Cladosporium.sphaerospermum (29.7%), C.cladosporioides (6.9%), Alternaria.alternata (13.9%) and U. atrum (5%).The predominance of these dark-coloured fungiin air is discussed and is attributed to one orboth of two hypotheses. Aspergillus (9spp., 4.3%) and Penicillium (8 spp.,3.95%) came next and were represented mainlyby A.niger (1.3%) andP. chrysogenum (2.4%).Spore showers of C.cladosporioides, C. sphaerospermum, Penicillium chrysogenum and Myrotheciumverrucaria were noticed with no regularseasonal pattern.The monthly number of species ranalmost parallel to the total count of fungi.The broadest species spectrum (25–29 spp.) wasrecorded in the summer months May–August 1997and the narrowest (11–12 spp.) in February andMarch 1998.The highest monthly wind velocity wasregularly associated with higher fungal colonycounts than in case of the lowest velocity. Onthe other hand, wind direction did not exhibitany regular correlation either with the colonycounts of fungi or with the wind velocity. Highwind velocity could bring more fungal spores tobe sedimented on the surface of exposed agar.Diurnal fluctuations of fungal spores offungi displayed one peak at 12 noon when thehighest temperature and wind velocity, and theleast relative humidity were recorded and onetrough at midnight.     

Autoregulatory Properties of (+)-Thujopsene and Influence of Environmental Conditions on Its Production by <Emphasis Type="Italic">Penicillium decumbens</Emphasis>

A Penicillium decumbens strain was collected from a water-damaged building, and the production of microbial volatile organic compounds (MVOCs) was investigated by means of headspace solid-phase microextraction, followed by GC-MS analysis. The strain was characterized by a high production of (+)-thujopsene. The influence of various temperatures, relative humidity (RH) values, substrates, and inoculum concentrations on fungal growth and (+)-thujopsene production was studied. The optimal temperature and relative humidity for P. decumbens growth were 30°C and 100% RH, respectively. In general, the more favourable the incubation parameters were for growth, the faster maximum (+)-thujopsene production was reached. Moreover, the antifungal activity of thujopsene was tested against 16 fungal strains. The growth of five of these fungal strains was negatively affected both by thujopsene alone and when grown in contact with the MVOCs produced by P. decumbens. Following these results and since growth of P. decumbens itself was also inhibited by thujopsene, an autoregulatory function for this compound was proposed. Few data are present in the literature about chemical communication between fungi. The present research could, therefore, contribute to understanding fungal metabolism and behaviour in indoor environments.