First report of internal black rot on Carica papaya fruit caused by Fusarium sulawesiense in China

Papaya (Carica papaya L.) is a tropical fruit consumed worldwide due to its nutritional, medicinal and pharmacological properties. In China, papaya was widely planted in Guangdong, Guangxi, Hainan, Yunnan, Fujian and Taiwan provinces. From September to December in 2015-2020, fruit with internal black rot disease was observed in papaya plantation in Xuwen, Guangdong province (N20°20’9”; E110°14’45”), approximately 5% fruits on about 85% trees were infected every year. The infected fruits showed the symptom of ‘false-ripening’ and the pericarp color changed from green to yellow earlier than that of normal fruits. In the cavity of diseased fruits, the sarcocarp black rotted and conspicuous mycelia were observed. Mycelia and infected tissues from symptomatic fruits were picked up, placed on potato dextrose agar (PDA) with 50mg/L ampicillin and incubated at 25± 2 ℃ in the dark. The fungus was purified by spore dilution plate method. Fast-growing colonies with dense, floccose, cottony mycelium were initially white gradually becoming buff brown. Macroconidia were falcate, 3-5 septa with foot-shaped cell and 10.35-41.50 (av. 25.41±6.82) ×1.90-5.95 (av. 3.67±0.85) µm (n>140) in size after 7 days of incubation on carnation leaf agar (CLA). There were scarce microconidia. Chlamydospores were intercalary, solitary or in chains, globose or irregular, hyaline to light brown. The morphological characteristics of the fungus were similar to that of Fusarium sulawesiense (Maryani et al. 2019). The internal transcribed spacer region (ITS) (KU881904 and KY436233), translation elongation factor 1-alpha (tef1) (KU894408 and KY436232), and RNA polymerase second largest subunit (rpb2) (KU894409 and KY436231) were sequenced from two isolates to cofirm species identification. Blast analysis in the FUSARIUM-ID and the NCBI databases revealed above 99 to 100% identity match with the F. sulawesiense strains NRRL34056, NRRL34059, NRRL34004 and NRRL43730 (Xia et al 2019). Maximum likelihood (ML) analysis and Bayesian inference (BI) based on the concatenated sequences using RAxML v.1.0.0 and MrBayes v. 3.2.1 software revealed that the isolates were resolved in the same clade with the F. sulawesiense strains. Thus, the fungus was identified as F. sulawesiense based on morphological characteristics and molecular criteria. To confirm pathogenicity, five healthy fruits were injected with 200 μl of spore suspension (approximately 104 spores/ml) in the field and laboratory, and isovolumetric sterile water served as control. Each fruit was sealed with a plastic bag and kept at natural temperature (about 25-30 ℃). All the inoculated fruits developed typical symptoms after 30 days in the field and 15 days in the laboratory, whereas no symptoms were observed on the control fruits. F. sulawesiense was reisolated from inoculated fruits, but not from non-inoculated fruits. F. sulawesiense displayed a broad host which included Oryza sativa, Musa nana, Citrus reticulata, and Colocasia esculenta etc. in China (Wang et al. 2019). To our knowledge, this is the first report of F. sulawesiense causing internal black rot on papaya fruit. This work is important for papaya growers to prevent this disease in time.

Mycotoxin-contaminated food and feed in Saudi Arabia: review of occurrence and toxicity

Introduction. Mycotoxins are reported to have a considerable impact on the health of consumers. There has been plentiful research into the effects of mycotoxins, fungi, and bacteria on the safety and quality of food and feed. This research paper reviews the literature on mycotoxins. Study objects and methods. The study focused on mycotoxins in food and feed produced in Saudi Arabia. We reviewed literature on the occurrence and health impacts of foodborne mycotoxins. We also studied the presence of mycotoxins in herbs, nuts, cereals, dried fruits and vegetables, infant formulas and baby foods, as well as dairy products. Finally, the paper offers a review of mycotoxin analysis methods. Results and discussion. The findings showed that mycotoxins attract a lot of scientific interest in Saudi Arabia. Certain types of mycotoxins (zearalenone, aflatoxins) and fungi (Aspergillus flavus, Penicillium chrysogenum, and Aspergillus niger) were common in the samples (isolates) of products tested in the Saudi regions. Furthermore, the researchers used different techniques of analysis such as the HPLC method, dilution plate method, thin layer chromatography, total plate count method, and seed-plate method to detect, identify, and isolate mycotoxins. Conclusion. Most importantly, the results showed that mycotoxins have serious health impacts on consumers and most of the contamination cases are caused by improper storage conditions and/or inappropriate handling and harvesting practices.

Prevalence of lipase producer Aspergillus niger in nuts and anti-biofilm efficacy of its crude lipase against some human pathogenic bacteria

Nuts are the natural source of healthy lipids, proteins, and omega-3. They are susceptible to fungal and mycotoxins contamination because of their high nutritional value. Twenty-five species comprising 12 genera were isolated from 80 samples of dried fruits and nuts using the dilution plate method. Peanut recorded the highest level of contamination followed by coconut; almond and raisin were the lowest. Aspergillus was the most prevalent genus and A.niger, was the most dominant species. The morphological identification of the selected A.niger isolates as they were detected in high frequency of occurrence was confirmed by using 18SrRNA sequence. Ochratoxin biosynthesis gene Aopks was detected in the tested isolates. Lipase production by the selected A.niger isolates was determined with enzyme activity index (EAI) ranging from 2.02 to 3.28. A.niger-26 was the highest lipase producer with enzyme activity of 0.6 ± 0.1 U/ml by the trimetric method. Lip2 gene was also detected in the tested isolates. Finally, the antibacterial and antibiofilm efficiency of crude lipase against some human pathogens was monitored. Results exhibited great antibacterial efficacy with minimum bactericidal concentration (MBC) of 20 to 40 µl/100 µl against Escherichiacoli, Pseudomonasaeruginosa, Proteusmirabilis, and Methicillin-resistant Staphylococcusaureus (MRSA). Interestingly, significant anti-biofilm efficacy with inhibition percentages of 95.3, 74.9, 77.1 and 93.6% was observed against the tested pathogens, respectively.

Morphological and molecular identification of Beauveria bassiana from agricultural soils

The soil environment is an important reservoir for a wide variety of entomopathogenic fungi, which can significantly contribute to the control of insect populations, especially on agricultural pests. Comparison of entomopathogens with conventional chemical pesticides, there are advantages in using biological control agents, such as human safety and other non-target organisms; pesticide residues are minimized in food and biodiversity increased in managed ecosystems. The main objective of this study was to detect and identify the entomopathogenic fungi from agriculture soils based on morphological and molecular identification. Total of 115 soil samples were collected in spring (before sowing) from different crop fields in “Unjin” and “Nart” Research and Education Centers of the university, which are located in Bornuur sum, Tuv Province from 2016 to 2018. Isolation of entomopathogenic fungus, Вeauveria bassiana was isolated using Dilution plate method in Peptone Dextrose Agar Yeast. Based on microscopic observation, hyphae branched and formed conidiogene cells, and single cell В. bassiana conidium was round and tend to oval with hyaline color. Colonies on PDAY were white to pale yellow and sometimes red pigments in reverse. Using PCR method with primer specific for identification В. bassiana, molecular analysis confirmed that all six isolates has same size of band which, appeared on agarose gel.

Cultured Microfungal Communities in Biological Soil Crusts and Bare Soils at the Tabernas Desert, Spain

We examined the variations in microfungal communities from different surface types (cyanobacterial crusts, lichen-dominated crusts, and noncrusted bare surface) at two different positions—north-oriented slope and sun-exposed plain in the Tabernas Desert, Spain. A total of 77 species from 46 genera was isolated using the soil dilution plate method. The studied mycobiota, similar to the majority of desert mycobiotas, was dominated by melanin-containing species. However, in the Tabernas crusts, unlike the studied crusts of the Negev Desert (Israel) and the Tengger Desert (China), melanized fungi with large multicellular spores were much less abundantly represented, while the thermotolerant group, Aspergillus spp., remarkably contributed to the communities’ structure. Density of microfungal isolates positively correlated with chlorophyll content indicating possible significant influence of organic matter content on fungal biomass. The variations in crust composition, biomass, and the position of habitats were accompanied by the variations in microfungal community structure, diversity level, and isolate densities, with the communities at the plain sun-exposed position being much less variable than the communities at the north-oriented position. The study shows that microclimatic and edaphic factors play an essential role in the development of crust and noncrust microfungal communities, and their structure can be a sensitive indicator of changing environmental conditions at a microscale.

Enrichment and Biopelletization of Phosphate Solubilizing Diazotrophic Bacterial Isolates Using Earthworm as a Tool

Aims: The beneficial role of earthworm Eudrilus eugeniae in enhancing the populations of two phosphate solubilizing diazotrophic isolates viz., Bacillus sp. (DT) and Azotobacter chroococcum (DT), isolated from the rhizosphere of finger millet [Eleusine coracana (L) Gaertn] was studied. Place and Duration of Study: The experiments were conducted at the campus of M/s. Chaitra Biofertilizers and Chemicals (P) Ltd, Mysore, between January – June 2018. Methodology: To the glass jars containing three week old partially decomposed green leafy material and cow dung, 0.5 gram of lignite based phosphate solubilizing diazotrophic isolates were added. To this eight medium sized earthworms were allowed and moisture is maintained at 50-60%. The population of isolates in the gut of earthworm and vermicasts were estimated on 2nd, 20th, 40th and 60th day by dilution plate method using Pikovskaya’s and Jensen’s agar medium Results: The population of Bacillus sp. (DT) and A. chroococcum (DT) increased by 22.14, 42.14 and 97.62 percent in the fore gut, mid gut and hind gut regions respectively while A. chroococcum (DT) by 24.05, 41.19 and 110.95 percent as compared to their initial population in the feeding material. Both the isolates increased enormously in the vermicasts up to 40th day and thereafter declined as recorded in 60 days old vermicasts. Bacillus sp. (DT) increased by 196.91 and 247.16 percent in 20 and 40 day old vermicasts and decreased by 54.72 percent on 60th day while A. chroococcum (DT) recorded an increase of 217.34 and 270.77 percent and thereafter declined by 41.18 percent in 60 days old casts. Conclusion: The earthworm can be used as a tool for secondary level multiplication and biopelletization of the isolates to produce enriched vermicompost for use in finger millet cultivation. It also indicated that the vermicasts should be applied soon after it is harvested.

Greenhouse study on the influence of natural biostimulators and fertilizers on improving bean plants growth and microbial activity in oil-polluted soil

The presence of oil hydrocarbons and salts in soils has as consequence the poor growth of plants due to the low availability of nutrients caused by unappropriate water regime, increased soil toxicity and the deterioration of soil structure. The present research has as main purpose the improvement of the bean plants (cultivar UNIDOR) growth and to stimulate microbial activity in rhizosphere using various natural stimulators and fertilizers (AMALGEROL,VERMIPLANT, POCO, IGUANA and FORMULEX) in greenhouse experiments on oil-polluted soil from Icoana farm, Olt county. The total counts of microorganisms (heterotrophic aerobic bacteria and filamentous fungi) were estimated by dilution plate method. The global microbial activity was measured as soil respiration by substrate-induced respiration method. Total bean plants biomass accumulation significantly increased under the influence of natural stimulators and fertilizers added (excepting IGUANA) when compared to untreated control. The best results were recorded for VERMIPLANT. Natural products induced activation of physiological activities of soil microbiota reflected in increased values of CO2 released by respiration, lower levels of colonization with phytopathogenic species, the domination of fluorescent pseudomonads, actinomycetes and cellulolytic fungi, too. The particular aspect of paper circular chromatograms reflected qualitative differences between rhizosphere soils determined by the effect of treatments with natural stimulators and fertilizers.

Isolation of Potential Alkaliphilic Cellulase-Producer Strains from Limestone Area of Perlis

Alkaliphilic cellulases-producer fungi were isolated from soil of limestone areas in Perlis. The potential strain was isolated by soil dilution plate method on enriched selective medium using CMC as substrate at different pH levels. Eleven isolates of different morphological colonies were screened using the hydrolysis capacity test by Gram’s iodine. Out of eleven colonies, five showed positive results as the hydrolysis zone formed. BK1 showed the highest hydrolysis capacity among all sample strains for every pH levels. Eventually, four strains were selected to be further explored as cellulolytic fungi for the production of alkaline cellulase in the future.

Microfungi in the soil beneath common oak and their effect on Armillaria occurrence

Microfungal assemblages in a soil beneath 30- and 50·year-old oaks and their 2-year-old stumps were studied using the soil dilution plate method. A total of 98 culturable microfungi were isolated. Compared to the living oaks before felling and the control living oaks, the density of <i>Mortierella macrocystis, Penicillium jonczewskii, Pseudogymnoascus roseus Sporothrix schenckii, Tolypoccladiumum inflatum</i> and <i>Umbelopsis vinacea</i> sigificantly inacased in the soil beneath slumps in the 32- and 52-year-old stands. Density of <i>Aspergillus kanagawaensis, Monodictys lepraria, P. daleae</i> and sterile dematiaceous hyphomycetes increased significantly in the 32-year-old stand and <i>Chrysosporium merdarium</i> in the 52·year-old stand. These fungi are known 'stimulants' of <i>Armillaria</i> rhizomorph formation. It is suggested that the increase in density of <i>Armillaria</i> rhizomorph 'stimulants' in a soil beneath oak stumps may increase the possibility of colonization of stumps by <i>Armillaria</i>.

Sludy of the Dermatophytes in the Students Houses of Minia University, Egypt

A survey of dermatophytes and other fungi was carried out in 100 air - dust samples from bedrooms and dinning halls of male and female student resident houses. By hair baiting technique the common dermatophytes were obtained namely <i>Microsporum canis, M. gypseum</i> and <i>Trichophyton mtntagrophytes</i>. Also five species of <i>Chrysasporium</i> were isolated in the following order of dominance <i>C. tropicum, C. keratinophilum, C. indicum, C. pannicola</i> and <i>C. quecnslandicum</i>. By dilution plate method, 37 species representing 20 genera of which <i>Aspergilus niger, A. flavus, Rhizopus nigricans, Penicillium chrysogenum</i> and <i>Cladosporium cladosporioides</i> were most frequently isolated.