Resistant fungi isolated from contaminated uranium mine in Brazil shows a high capacity to uptake uranium from water

The Osamu Utsumi uranium mine occupies a 20 km² area in the city of Caldas, which is located in the state of Minas Gerais, Brazil. Since mining activities ended at Osamu Utsumi 24 years ago, the surrounding area has become contaminated by acid effluents containing high concentrations of uranium. Thus, the aim of this study was to assess the uranium bioremediation capacity of 57 fungi isolated from the mine area. In tolerance tests, 38% (22) of the fungal isolates were considered tolerant to uranium, including 10 Penicillium species. At a uranium concentration of 2000 mg L^-1 48 fungi did not exhibit mycelial growth index inhibition. Minimal inhibitory concentration (MIC) analysis showed growth of 25 fungi above a uranium concentration of 8000 mg L^-1. At high uranium concentrations, some fungi (i.e., Talaromyces amestolkiae and Penicillium citrinum) showed morphological changes and pigment (melanin) production. Among the fungal isolates, those considered to be more tolerant to uranium were isolated from soil and sediment samples containing higher concentrations of heavy metal. When comparing the results of resistance/tolerance tests with those for uranium biosorption capacity, we concluded that the fungi isolated from the Osamu Utsumi mine with the best potential for uranium bioremediation were Gongronella butleri, Penicillium piscarium, Penicillium citrinum, Penicillium ludwigii, and Talaromyces amestolkiae. Biosorption tests with live fungal biomass showed that 11 species had a high potential for uranium uptake from contaminated water.

Synthesis and Antiviral/Fungicidal/Insecticidal Activities Study of Novel Chiral Indole Diketopiperazine Derivatives Containing Acylhydrazone Moiety

On the basis of the mechanism of acylhydrazone compounds inhibiting the assembly of TMV CP and the unique structural characteristics of diketopiperazine ring, a series of optically pure indole diketopiperazine acylhydrazone were designed and synthesized. In order to systematically study the effect of the spatial configuration of the compounds on the antiviral activity, four compounds with different spatial configurations at C6 and C12a were also prepared. The bioassay results indicated that most of these new compounds displayed moderate to good antiviral activity, among which compounds 23, 25, 27, 28, 31, and 5d showed a significantly higher activity than that of commercial ribavirin. An in-depth structure-activity relationship investigation showed that the spatial conformation was one of the most important factors in adjusting antiviral activity; the research results provided information about the possible optimum configuration for interaction of this molecular with its target protein. At the same time, these new compounds also exhibited broad-spectrum fungicidal activities against 14 kinds of phytopathogenic fungi. What's more, some of these compounds exhibited good insecticidal activity to Plutella xylostella and Culex pipiens pallens.

Discovery of Tryptanthrins as Novel Antiviral and Anti-Phytopathogenic-Fungus Agents

Plant diseases seriously affect the yield and quality of crops and are difficult to control. Tryptanthrin and its derivatives (tryptanthrins) were synthesized and evaluated for their antiviral activities and fungicidal activities. We found that tryptanthrins have good antiviral activities against tobacco mosaic virus (TMV) for the first time. Most of the tryptanthrins showed higher anti-TMV activities than that of ribavirin (inhibitory rates of 40, 37, and 38% at 500 μg/mL for inactivation, curative, and protection activities in vivo, respectively). Compound 3n (inhibitory rates of 52, 49, and 54% at 500 μg/mL for inactivation, curative, and protection activities in vivo, respectively) and compound 14 (inhibitory rates of 51, 48, and 53% at 500 μg/mL for inactivation, curative, and protection activities in vivo, respectively) emerged as new antiviral lead compounds with excellent antiviral activities. Compound 16 was selected for further antiviral mechanism research, which revealed that compound 16 could inhibit virus assembly by decomposing 20S coat protein (CP) disk. Molecular docking results showed that compounds 3n and 14, which have higher antiviral activities in vivo than that of compound 16, do show stronger interaction with TMV CP. Further fungicidal activity tests showed that tryptanthrins displayed broad-spectrum fungicidal activities, especially for compound 16. These compounds showed good selectivity to Physalospora piricola. In the current study, a small molecular library of tryptanthrin was constructed and the bioactivity spectrum of these compounds was broadened, which lays a foundation for their application in plant protection.

Unexpected Propagation of Ultra-Lean Hydrogen Flames in Narrow Gaps

Very lean hydrogen flames were thought to quench in narrow confined geometries. We show for the first time how flames with very low fuel concentration undergo an unprecedented propagation in narrow gaps: H_{2}-air flames can survive very adverse conditions by breaking the reaction front into isolated flame cells that travel steadily in straight lines or split to perform a fractal-like propagation that resembles the pathway of starving fungi or bacteria. The combined effect of hydrogen mass diffusivity and intense heat losses act as the two main mechanisms that explain the experimental observations.

Detection of potential biodeterioration risks for tempera painting in 16th century exhibits from State Tretyakov Gallery

In this study, we investigated biodeterioration of materials used in tempera painting by analyzing the structure of the microbiome in ancient tempera paintings exhibited in State Tretyakov Gallery, Moscow, Russia. Samples were obtained from 16^th-century paintings, including a grand Russian Orthodox icon “The Church Militant” (all exhibits were without visible signs of biodeterioration), and from surrounding walls and ceilings (with vast zones of visible microbial growth). A number of microorganisms isolated from visible signs of environmental bio-damage were also detected in tempera paintings kept in temperature- and humidity-controlled conditions unfavorable for the growth of microflora. To determine the biodegrading potential of the microbiome for tempera paintings, we developed a set of mock layers from paintwork materials used in tempera painting of 16^th century and their modern analogues and inoculated them with cultures containing filamentous fungi and bacteria. The susceptibility to microbial degradation of individual tempera painting materials was examined by micro-Fourier Transform Infrared (FTIR) spectroscopy, which enabled detection of even invisible signs of biodeterioration. The results indicate that the microorganisms isolated from paintings and surrounding areas in the museum are capable of causing significant damage of various tempera materials, among which varnishes were the most resistant; however, the addition of antiseptic (sodium pentachlorophenolate) can inhibit microbial growth on sturgeon glue.

Fungal isolates findings of sputum samples in new and previously treated cases of pulmonary tuberculosis in dr. soetomo hospital surabaya, Indonesia

BACKGROUND

Fungal infections generally occur in immunosuppressive patients. Long-term tuberculosis (TB) treatment facilitates the occurrence of fungal infections, such as long-term antibiotics administration which is immunosuppressive agents and increases the opportunity of infections. Other factors may be correlated with fungal infection such as age, sex, malnutrition, smoking, diabetes mellitus, lung lesion severity, and the presence of multidrug-resistant TB. This study aims to identify and analyze the proportion of fungal isolates findings in the sputum of new and previously treated cases of pulmonary TB patients.

METHODS

This was an observational analytic study with a cross-sectional design of all pulmonary TB patients who were hospitalized in Dr. Soetomo Hospital Surabaya. Sputum samples were inoculated on Sabouraud's dextrose agar medium. The growth of visible colonies was identified by Lactophenol Cotton Blue staining using direct microscopy.

RESULTS

Fungal isolates were found in 148/193 (77%) pulmonary TB patients. Candida species was found 99% among 148 fungal positive culture. Candida albicans was the most common found fungal species (54.05%), followed by Candida sp (26.35%), Candida glabrata (10.13%), Candida krusei (5.4%), and Candida tropicalis (1.35%). Previously treated cases, sex, malnutrition, and smoking were variables correlated with fungal isolates finding with P value of 0.015, 0.006, 0.010, and <0.001, respectively.

CONCLUSION

The proportion of fungal positive cultures in previously treated cases was higher than in new cases. C. albicans was the most common fungal species both in previously treated cases and new cases of pulmonary TB.

Contribution of surface application of chitosan-thyme and chitosan-rosemary essential oils to the volatile composition, microbial profile, and physicochemical and sensory quality of dry-fermented sausages during storage

The effect of chitosan (C), chitosan enriched with thyme (CT) or rosemary (CR) essential oils, and potassium sorbate (PS) against superficial fungal growth was investigated in fermented sausages during 3 months of storage at 4 °C. For control groups, distilled water (DW) and acetic acid (AA) were used. PS, C, CT and CR treatments inhibited fungal growth on casings while they resulted in lower Gram(+) catalase(+) cocci, Enterobacteriaceae, mold and yeast counts in sausages. Lower TBARS values were determined for CT and CR (p < .05). A total of 44 and 64 volatile compounds were identified in sausages and casings, respectively. Sausages coated with C, CT or CR had acceptable sensory attributes at the end of storage; however, DW and AA groups were rejected in the second and third month (p < .05), respectively, due to intense fungal growth which resulted in sensory defects.

The influence of waste from electronic cigarettes, conventional cigarettes and heat-not-burn tobacco products on microorganisms

Tobacco smoking, especially conventional cigarettes, is widespread throughout the world. Simultaneously, there is a growing interest in new alternative products that allow delivering nicotine to the users' organisms, including electronic cigarettes and heat-not-burn tobacco products. However, there are few scientific reports regarding the effect of waste generated from the above-mentioned products on microorganisms. The aim of the manuscript was to investigate the influence of substances leached from conventional cigarette butts, butts from heat-not-burn tobacco products, cartridges and e-liquids for electronic cigarettes on microorganisms. The commercial multispecies MARA (microbial assay for risk assessment) test and non-selected microorganisms from the Brynica River (Poland), as well as an effluent from the wastewater treatment plant (Sosnowiec-Zagórze, Poland), were used in the ecotoxicity assessment of the investigated waste. The results of the experiments revealed that the waste from electronic cigarettes, i.e. cartridges and e-liquids, does not pose a considerable threat to the microbiocenosis. On the other hand, a particularly strong ecotoxic effect on the investigated microorganisms has been reported for leachate from smoked cigarette butts and butts from heat-not-burn tobacco products. Their high ecotoxicity combined with a high supply is worrying and it can require interventions to protect the aquatic environment. The retention of the waste can have an adverse effect on microorganisms in reservoirs surface waters or a sludge activity in wastewater treatment plants.

Bacterial and fungal ecology on air conditioning cooling coils is influenced by climate and building factors

The presence of biofilms on the cooling coils of commercial air conditioning (AC) units can significantly reduce the heat transfer efficiency of the coils and may lead to the aerosolization of microbes into occupied spaces of a building. We investigated how climate and AC operation influence the ecology of microbial communities on AC coils. Forty large-scale commercial ACs were considered with representation from warm-humid and hot-dry climates. Both bacterial and fungal ecologies, including richness and taxa, on the cooling coil surfaces were significantly impacted by outdoor climate, through differences in dew point that result in increased moisture (condensate) on coils, and by the minimum efficiency reporting value (MERV 8 vs MERV 14) of building air filters. Based on targeted qPCR and sequence analysis, low efficiency upstream filters (MERV 8) were associated with a greater abundance of pathogenic bacteria and medically relevant fungi. As the implementation of air conditioning continues to grow worldwide, better understanding of the factors impacting microbial growth and ecology on cooling coils should enable more rational approaches for biofilm control and ultimately result in reduced energy consumption and healthier buildings.

Effects of Soil Amendments on Microbial Activities in a Typical Cd-Contaminated Purple Field Soil, Southwestern China

In this study, three soil amendments (inorganic, liming, or organic-inorganic materials) were used in a Cd-contaminated purple field soil to investigate their impacts on soil Cd availability, enzyme (urease, catalase, sucrase, and acid phosphatase) activities, microbial biomass (carbon/nitrogen) and type (bacteria, fungi, and actinomycetes) in mustard and corn trials. Results showed that soil amendments generally decreased soil exchangeable Cd, fungi and bacterial populations while increasing the activities of all the four soil enzymes tested, microbial biomass carbon and populations of actinomycetes (p < 0.05). Soil pH and microbial biomass nitrogen did not exhibit any significant response (p > 0.05) whereas stronger effects appeared in soil organic matter and available nutrients (nitrogen, phosphorous and potassium; p < 0.05). However, only soil available phosphorous significantly correlated with soil microbial activity in both mustard and corn trails (p < 0.05). Thus, application of phosphorous-containing amendments should be considered for promoting soil health in the remediation of the Cd-contaminated purple soils.

A snapshot of microbial diversity and function in an undisturbed sugarcane bagasse pile

BACKGROUND

Sugarcane bagasse is a major source of lignocellulosic biomass, yet its economic potential is not fully realised. To add value to bagasse, processing is needed to gain access to the embodied recalcitrant biomaterials. When bagasse is stored in piles in the open for long periods it is colonised by microbes originating from the sugarcane, the soil nearby or spores in the environment. For these microorganisms to proliferate they must digest the bagasse to access carbon for growth. The microbial community in bagasse piles is thus a potential resource for the discovery of useful and novel microbes and industrial enzymes. We used culturing and metabarcoding to understand the diversity of microorganisms found in a uniquely undisturbed bagasse storage pile and screened the cultured organisms for fibre-degrading enzymes.

RESULTS

Samples collected from 60 to 80 cm deep in the bagasse pile showed hemicellulose and partial lignin degradation. One hundred and four microbes were cultured from different layers and included a high proportion of oleaginous yeast and biomass-degrading fungi. Overall, 70, 67, 70 and 57% of the microbes showed carboxy-methyl cellulase, xylanase, laccase and peroxidase activity, respectively. These percentages were higher in microbes selectively cultured from deep layers, with all four activities found for 44% of these organisms. Culturing and amplicon sequencing showed that there was less diversity and therefore more selection in the deeper layers, which were dominated by thermophiles and acid tolerant organisms, compared with the top of pile. Amplicon sequencing indicated that novel fungi were present in the pile.

CONCLUSIONS

A combination of culture-dependent and independent methods was successful in exploring the diversity in the bagasse pile. The variety of species that was found and that are known for biomass degradation shows that the bagasse pile was a valuable selective environment for the identification of new microbes and enzymes with biotechnological potential. In particular, lignin-modifying activities have not been reported previously for many of the species that were identified, suggesting future studies are warranted.

Substitution of manure for chemical fertilizer affects soil microbial community diversity, structure and function in greenhouse vegetable production systems

Soil microbial communities and enzyme activities together affect various ecosystem functions of soils. Fertilization, an important agricultural management practice, is known to modify soil microbial characteristics; however, inconsistent results have been reported. The aim of this research was to make a comparative study of the effects of different nitrogen (N) fertilizer rates and types (organic and inorganic) on soil physicochemical properties, enzyme activities and microbial attributes in a greenhouse vegetable production (GVP) system of Tianjin, China. Results showed that manure substitution of chemical fertilizer, especially at a higher substitution rate, improved soil physicochemical properties (higher soil organic C (SOC) and nutrient (available N and P) contents; lower bulk densities), promoted microbial growth (higher total phospholipid fatty acids and microbial biomass C contents) and activity (higher soil hydrolase activities). Manure application induced a higher fungi/bacteria ratio due to a lower response in bacterial than fungal growth. Also, manure application greatly increased bacterial stress indices, as well as microbial communities and functional diversity. The principal component analysis showed that the impact of manure on microbial communities and enzyme activities were more significant than those of chemical fertilizer. Furthermore, redundancy analysis indicated that SOC and total N strongly influenced the microbial composition, while SOC and ammonium-N strongly influenced the microbial activity. In conclusion, manure substitution of inorganic fertilizer, especially at a higher substitution rate, was more efficient for improving soil quality and biological functions.

A Low-Cost Humidity Control System to Protect Microscopes in a Tropical Climate

Introduction

A clean and functional microscope is necessary for accurate diagnosis of infectious diseases. In tropical climates, high humidity levels and improper storage conditions allow for the accumulation of debris and fungus on the optical components of diagnostic equipment, such as microscopes.

Objective

Our objective was to develop and implement a low-cost, sustainable, easy to manage, low-maintenance, passive humidity control chamber to both reduce debris accumulation and microbial growth onto the optical components of microscopes.

Methods

Constructed from easily-sourced and locally available materials, the cost of each humidity control chamber is approximately $2.35 USD. Relative humidity levels were recorded every 30 minutes over a period of 10 weeks from two chambers deployed at the Belize Vector and Ecology Center and the University of Belize.

Results

The humidity control chamber deployed at the University of Belize maintained internal relative humidity at an average of 35.3% (SD = 4.2%) over 10 weeks, while the average external relative humidity was 86.4% (SD = 12.4%). The humidity control chamber deployed at the Belize Vector and Ecology Center effectively maintained internal relative humidity to an average of 54.5% (SD = 9.4%) over 10 weeks, while the average external relative humidity was 86.9% (SD = 12.9%).

Conclusions

Control of relative humidity is paramount for the sustainability of medical equipment in tropical climates. The humidity control chambers reduced relative humidity to levels that were not conducive for fungal growth while reducing microscope contamination from external sources. This will likely extend the service life of the microscopes while taking advantage of low-cost, locally sourced components.

Calcium-Calmodulin-Calcineurin Signaling: A Globally Conserved Virulence Cascade in Eukaryotic Microbial Pathogens

Calcium is an abundant intracellular ion, and calcium homeostasis plays crucial roles in several cellular processes. The calcineurin signaling cascade is one of the major pathways governed by intracellular calcium. Calcineurin, a conserved protein from yeast to humans, is a calcium-calmodulin-dependent serine-threonine-specific phosphatase that orchestrates cellular stress responses. In eukaryotic microbial pathogens, calcineurin controls essential virulence pathways, such as the ability to grow at host temperature, morphogenesis to enable invasive hyphal growth, drug tolerance and resistance, cell wall integrity, and sexual development. Therefore, the calcineurin cascade is an attractive target in drug development against eukaryotic pathogens. In the present review, we summarize and discuss the current knowledge on the roles of calcineurin in eukaryotic microbial pathogens, focusing on fungi and parasitic protists.

Cultivation Area Affects the Presence of Fungal Communities and Secondary Metabolites in Italian Durum Wheat Grains

In this study, durum wheat kernels harvested in three climatically different Italian cultivation areas (Emilia Romagna, Umbria and Sardinia) in 2015, were analyzed with a combination of different isolation methods to determine their fungal communities, with a focus on Fusarium head blight (FHB) complex composition, and to detect fungal secondary metabolites in the grains. The genus Alternaria was the main component of durum wheat mycobiota in all investigated regions, with the Central Italian cultivation area showing the highest incidence of this fungal genus and of its secondary metabolites. Fusarium was the second most prevalent genus of the fungal community in all cultivation environments, even if regional differences in species composition were detected. In particular, Northern areas showed the highest Fusarium incidence, followed by Central and then Southern cultivation areas. Focusing on the FHB complex, a predominance of Fusariumpoae, in particular in Northern and Central cultivation areas, was found. Fusariumgraminearum, in the analyzed year, was mainly detected in Emilia Romagna. Because of the highest Fusarium incidence, durum wheat harvested in the Northern cultivation area showed the highest presence of Fusarium secondary metabolites. These results show that durum wheat cultivated in Northern Italy may be subject to a higher FHB infection risk and to Fusarium mycotoxins accumulation.

Short peptides secreted by Bacillus subtilis inhibit the growth of mold on fresh-cut pumpkin (Cucurbita pepo)

BACKGROUND

This study investigates the efficacy of short peptides secreted by Bacillus subtilis for fungal inhibition in fresh-cut pumpkin and for maintaining its shelf life.

RESULTS

Low-molecular-weight filtrate (LC < 1000 Da) of B. subtilis culture (BC) significantly lowered the total number of molds on fresh-cut pumpkin compared with the untreated control and a BC group after storage. Low-molecular-weight filtrate prevented the deterioration of sensory quality in a pumpkin incision, and reduced pectinase activity. It also inhibited the growth of Phytophthora capsici and Penicillium chrysogenum, and the activity of β-1,3-glucan synthase (GS) secreted by both molds. Fifty-seven GS-inhibiting peptides were screened from 95 LC peptides with two to five amino acid residues. The two most potent peptides, AWYW and HWWY, had strongly suppressive effects on the growth of P. capsici and P. chrysogenum.

CONCLUSION

Our study demonstrated that short peptides present in B. subtilis culture can play an important role in the maintenance of fresh-cut pumpkin by suppressing fungal growth. © 2019 Society of Chemical Industry.

The effect of an additive containing three Lactobacillus species on the fermentation pattern and microbiological status of silage

BACKGROUND

Appropriate combinations of lactic acid bacteria (LAB) strains should be selected to optimize the ensiling process, and the additives should be adjusted to the ensiled forage crops. The aim of this study was to determine the effect of inoculation with three Lactobacillus species on the chemical parameters and microbiological quality (beneficial and harmful microbiota) of grass silage.

RESULTS

Three species: L. paracasei (LPa), L. brevis (LB) and L. plantarum (LPl), isolated from sugar beet silage and characterized based on 16S rDNA sequences and biochemical parameters, were analyzed in the study. Single strains and their combinations were used as silage inoculants. The basic chemical and microbiological (qPCR) parameters of silages were determined. Based on the results of agglomerative hierarchical clustering (AHC) and principal component analysis (PCA) it was determined that silages inoculated with single LAB strains and LPa + LB and commercial additive (0+) were the best quality ones, particularly with regard to microbiological parameters and they effectively lowered the pH value. A consortium of three Lactobacillus species had no influence on silage quality, whereas LPa + LB and LPl + LB combinations as well as a commercial additive exerted positive effects. Inoculation inhibited the growth of toxin-producing fungi.

CONCLUSION

Only the appropriate LAB composition can improve the quality of the ensiled material (antagonistic relationship). Only the LPa + LB combination was able to improve the value of low dry silage; nevertheless, almost all combinations were able to reduced concentrations of toxin-producing fungi. © 2019 Society of Chemical Industry.

Distribution of Medically Relevant Antibiotic Resistance Genes and Mobile Genetic Elements in Soils of Temperate Forests and Grasslands Varying in Land Use

Antibiotic-resistant pathogens claim the lives of thousands of people each year and are currently considered as one of the most serious threats to public health. Apart from clinical environments, soil ecosystems also represent a major source of antibiotic resistance determinants, which can potentially disseminate across distinct microbial habitats and be acquired by human pathogens via horizontal gene transfer. Therefore, it is of global importance to retrieve comprehensive information on environmental factors, contributing to an accumulation of antibiotic resistance genes and mobile genetic elements in these ecosystems. Here, medically relevant antibiotic resistance genes, class 1 integrons and IncP-1 plasmids were quantified via real time quantitative PCR in soils derived from temperate grasslands and forests, varying in land use over a large spatial scale. The generated dataset allowed an analysis, decoupled from regional influences, and enabled the identification of land use practices and soil characteristics elevating the abundance of antibiotic resistance genes and mobile genetic elements. In grassland soils, the abundance of the macrolide resistance gene mefA as well as the sulfonamide resistance gene sul2 was positively correlated with organic fertilization and the abundance of aac(6')-lb, conferring resistance to different aminoglycosides, increased with mowing frequency. With respect to forest soils, the beta-lactam resistance gene blaIMP-12 was significantly correlated with fungal diversity which might be due to the fact that different fungal species can produce beta-lactams. Furthermore, except blaIMP-5 and blaIMP-12, the analyzed antibiotic resistance genes as well as IncP-1 plasmids and class-1 integrons were detected less frequently in forest soils than in soils derived from grassland that are commonly in closer proximity to human activities.

Cultivation and growth dynamics of endophytic fungi in a solid culture medium based on sugar beet pulp

BACKGROUND

The production of mycelium from endophytic fungi is of interest for applications ranging from inoculants and biofertilizers for crop production to fermentations for enzyme and metabolite production. The purpose of this study was to test the capacity of a solid growth medium based on beet pulp for growing different strains of endophytes.

RESULTS

The ergosterol content of inoculated medium was measured to estimate fungal growth. Several parameters related to the preparation of the growth medium, such as water content, calcium salts and incubation time, were evaluated. The greatest fungal biomass production was observed in a medium prepared with a 1:2 (beet pulp:water) ratio, containing calcium sulfate and carbonate. Strains belonging to different fungal species grew well in the growth medium finally selected, producing yields ranging from 50 to 500 g mycelium per kilogram of dry culture, after 22-27 days. Cultures containing up to 400 g beet pulp grew successfully, and could be scaled up.

CONCLUSION

A solid culture medium based on beet pulp supported the growth of diverse taxa of fungal endophytes. Both the water and calcium salt content of the growth medium affected the efficiency of mycelium production. Considering these factors, beet pulp medium was an excellent endophyte cultivation medium because of the high yield of fungal biomass observed, together with its ease of handling and scaling-up production. © 2019 Society of Chemical Industry.

Bryophytes and the symbiotic microorganisms, the pioneers of vegetation restoration in karst rocky desertification areas in southwestern China

In karst rocky desertification areas, bryophytes coexist with algae, bacteria, and fungi on exposed calcareous rocks to form a bryophyte crust, which plays an irreplaceable role in the restoration of karst degraded ecosystems. We investigated the biodiversity of crust bryophytes in karst rocky desertification areas from Guizhou Province, China. A total of 145 species in 22 families and 56 genera were identified. According to frequency and coverage, seven candidate dominant mosses were screened out, and five drought-resistant indexes of them were measured. Hypnum leptothallum, Racopilum cuspidigerum, and Hyophila involuta have high drought adaptability. We explored the interactions between two dominant mosses (H. leptothallum, H. involuta) and the structure of microbial communities in three karst rocky desertification types. Microbial diversity and function analysis showed that both moss species and karst rocky desertification types affect microbial communities. Moss species much more strongly affected the diversity and changed the community composition of these microbial groups. Bacteria were more sensitive in the microbiome as their communities changed strongly between mosses and drought resistance factors. Moreover, several species of fungi and bacteria could be significantly associated with three drought-resistant indexes: Pro (free proline content), SOD (superoxide dismutase activity), and POD (peroxidase activity), which were closely related to the drought adaptability of mosses. Our results enforced the potential role of moss-associated microbes that are important components involved in the related biological processes when bryophytes adapted to arid habitats, or as one kind of promoters in the distribution pattern of early mosses succession in karst rocky desertification areas.

Sources of food contamination in a closed hydroponic system

This study investigated potential contamination sources in a commercial, closed hydroponic system. Water, substrate and lettuce (Lactuca sativa) samples were evaluated for microbiological indicator populations, including aerobic plate count (APC), coliform bacteria (CB) and yeast and mould (YM). Listeria spp. detection via cultural enrichment and agglutination was negative for all samples. Peat moss substrate (postharvest) had the highest counts for APC (6·8 log CFU per g), CB (4·5 log MPN per g) and YM (5·1 and 4·8 log CFU per g respectively). Roots embedded in plugs demonstrated counts for all populations nearly as high as the substrate. Among water samples, a seedling water reservoir housing germinated plants yielded the highest count for APC (5·1 log CFU per g) and CB (2·4 log MPN per g) likely due to the large numbers of plugs and their close proximity in the reservoir. Harvested lettuce leaves demonstrated higher APC (4·1 log CFU per g) than preharvest leaves (1·7 log CFU per g) due to the transfer of microbes from the root ball. These data suggest that substrates are a significant potential source of contamination in hydroponic systems and likely facilitate microbial transfer to harvested leaves. There is, therefore, the need to further investigate mitigation of potential contamination events. SIGNIFICANCE AND IMPACT OF THE STUDY: Hydroponic production is known to provide safe, clean produce. This study, however, suggests that the hydroponic substrate (peat moss plug) is a possible source of contamination in the hydroponic system. This finding is important as most harvested hydroponic lettuces are packaged and sold with substrate and root ball intact. This implies a high probability of microbial transfer from the root ball to edible harvested lettuce leaves.

ISSR markers to explore entomopathogenic fungi genetic diversity: Implications for biological control of tobacco pests

Tobacco is one of the major industrial crops cultivated worldwide. Chemical control is the main method employed to reduce damage by insect pests. The use of entomopathogenic fungi represents an alternative to replace insecticides. The search for effective strains in the field constitutes a first step when developing a formulation. The objective of this work was to study genetic differences among isolates of entomopathogenic fungi obtained from tobacco grown soils using ISSR markers. The pathogenicity of the strains towards Helicoverpa gelotopoeon and Diabrotica speciosa was also assessed in order to search for a relationship between virulence and genetic diversity. Nineteen isolates were identified according to morphological features and molecular techniques as Beauveria bassiana (11) and Purpureocillium lilacinum (8). The diversity tree generated by ISSR analysis showed a high diversity among the strains. The pathogenicity towards H. gelotopoeon and D. speciosa was assessed and the logistic models generated showed that B. bassiana isolates LPSc1215 and LPSc1364 were the most pathogenic against both insect pests tested. In the diversity tree, these strains were grouped in a same cluster with a similarity level of approximately 85%, indicating a possible relationship between virulence and the band pattern generated.

The Relations Between Predatory Fungus and Its Rotifer Preys as a Noteworthy Example of Intraguild Predation (IGP)

Intraguild predation (IGP) is a widespread interaction combining predation and competition. We investigated a unique IGP example among predacious fungus Zoophagus sp. and two rotifers, the predacious Cephalodella gibba and the common prey Lecane inermis. We checked the influence of the fungus on its competitor C. gibba and their joint influence on shared prey L. inermis, and the impact of the competitive predator on the growth of predacious fungus. The experiment on grown mycelium showed that Zoophagus strongly, negatively influences the growth of C. gibba (intermediate consumer) whose number did not increase throughout the experiment. The intermediate consumer was also trapped by Zoophagus and become extinct when it was its only prey, whereas in the absence of the fungus and with unlimited access to prey, its number grew quickly. As only few C. gibba were trapped by fungi when common preys were present, competition for food seems to have stronger effect on intermediate consumer population than predation. The experiment with conidia of the fungus showed that intermediate consumer significantly limits the growth of Zoophagus by reducing the number of available prey. It was observed that although the fungus can trap C. gibba, the latter does not support its growth. Trapping the intermediate consumer might serve to eliminate a competitor rather than to find a source of food. The chances of survival for L. inermis under the pressure of the two competing predators are scarce. It is the first example of IGP involving representatives of two kingdoms: Fungi and Animalia.

Exocyst subunit BcSec3 regulates growth, development and pathogenicity in Botrytis cinerea

Botrytis cinerea is a saprophytic plant pathogenic fungus that can infect a variety of crops and cause gray mold, which leads to huge losses worldwide. The role of exocyst in fungal pathogenicity is being revealed. In this study, homologous recombination technology was used to knock out the exocyst subunit BcSec3 of B. cinerea, and it was found that the BcSec3 subunit plays a crucial role in the growth and pathogenicity of B. cinerea. Compared with the wild-type strain B05.10, the mycelial growth ability of the BcSec3 deletion strain was reduced by up to 49.8%, the conidia production capacity of the deletion strain was severely lost, and no sclerotia was formed. The polygalacturonase, is one of plant cell wall hydrolases, whose activity in BcSec3 deletion strain was significantly reduced. In the tomato leaves infection assay in vitro, the lesion area caused by the BcSec3 deletion strain was only 20% of the wild type after 5 days of infection. Observation by light microscope showed that the morphology of BcSec3 deletion strain mycelium was significantly changed, the mycelium became thinner and deformed, and the polarity growth was not obvious. Further observation with laser confocal microscopy and transmission electron microscopy was conducted. It was found that compared with the wild type, the number of vesicles in BcSec3 deleted cells reduced and localization and distribution of vesicles changed. In mutant cell, vesicles relatively concentrated in the cytoplasm, while in wild-type cell mainly concentrated inside the cell membrane. These evidences indicate that the exocyst subunit BcSec3 plays an important role in the growth, development and pathogenicity of B. cinerea.

Effects of Quorum Quenching on Biofilm Metacommunity in a Membrane Bioreactor

Quorum quenching (QQ) has received attention for the control of biofilms, e.g., biofilms that cause biofouling in membrane bioreactors (MBRs). Despite the efficacy of QQ on biofouling, it is elusive how QQ influences biofilm formation on membranes. A pilot-scale QQ-MBR and non-QQ-MBR were identically operated for 4 days and 8 days to destructively sample the membranes. QQ prolonged the membrane filterability by 43% with no harmful influence on MBR performance. qPCR showed no effect of QQ on microbial density during either of these time periods. Community comparisons revealed that QQ influenced the bacterial and fungal community structures, and the fungal structure corresponded with the bacterial structure. Metacommunity and spatial analyses showed that QQ induced structural variation rather than compositional variation of bacteria and fungi. Moreover, QQ considerably enhanced the bacterial dispersal across membrane during the early development. As the dispersal enhancement by QQ counteracted the ecological drift, it eliminated the distance-decay relationship, reflecting a neutral theory archetype of metacommunity. Network analyses showed that QQ substantially reduced the amount and magnitude of interactions, e.g., competition and cooperation, for bacteria and fungi, and weakened their network structures, irrespective of time. Additionally, QQ suppressed the growth of specific microbial species (e.g., Acinetobacter), abundant and widespread at the early stage. These findings suggest that QQ influenced the community dynamics at the regional and local levels, correspondingly the ecological selection and dispersal processes, during the biofilm development.