Rhizopus Arrhizus Research Articles

Hyphae of Rhizopus arrhizus and Lichtheimia corymbifera Are More Virulent and Resistant to Antifungal Agents Than Sporangiospores In Vitro and in Galleria mellonella.

Mucorales species cause debilitating, life-threatening sinopulmonary diseases in immunocompromised patients and penetrating wounds in trauma victims. Common antifungal agents against mucormycosis have significant toxicity and are often ineffective. To evaluate treatments against mucormycosis, sporangiospores are typically used for in vitro assays and in pre-clinical animal models of pulmonary infections. However, in clinical cases of wound mucormycosis caused by traumatic inoculation, hyphal elements found in soil are likely the form of the inoculated organism. In this study, Galleria mellonella larvae were infected with either sporangiospores or hyphae of Rhizopus arrhizus and Lichtheimia corymbifera. Hyphal infections resulted in greater and more rapid larval lethality than sporangiospores, with an approximate 10-16-fold decrease in LD50 of hyphae for R. arrhizus (p = 0.03) and L. corymbifera (p = 0.001). Liposomal amphotericin B, 10 mg/kg, was ineffective against hyphal infection, while the same dosage was effective against infections produced by sporangiospores. Furthermore, in vitro, antifungal susceptibility studies show that minimum inhibitory concentrations of several antifungal agents against hyphae were higher when compared to those of sporangiospores. These findings support using hyphal elements of Mucorales species for virulence testing and antifungal drug screening in vitro and in G. mellonella for studies of wound mucormycosis.

Degradation of crude oil and the pure hydrocarbon fractions by indigenous soil microorganisms

Petroleum hydrocarbons are a major concern due to their widespread distribution in the environment, and their harmful effects on humans. The use of biodegradation methods to clean soil that has been contaminated by spilt petroleum can be an effective remediation strategy. Therefore, in this study, the presence of indigenous microorganisms in soil contaminated with crude oil was investigated and their ability to degrade petroleum in vitro was studied. Three methods were used to detect crude oil and pure hydrocarbon degradation by bacterial and fungal isolates. Spectrophotometric method, 2,6-Dichlorophenol indophenol (DCPIP) method and hydrocarbon analysis was performed by GC–MS. Furthermore, PCR was carried out to detect the genes AlkB and PMO in the microbial communities. Seventeen bacterial isolates and 5 fungal isolates were recovered from 19 soil culture samples obtained from three different oil-contaminated sites at Taq-taq (TTOPCO) oil field and from a control site without oil contamination. The bacterial samples were identified culturally and morphologically, and the results were validated by genetic analysis. The results of this study revealed that the indigenous bacterial and fungal isolates had a high capacity to degrade crude oil and pure hydrocarbon fractions. Our results provide insight into the great abilities of Bacillus anthracis, Bacillus cereus, Achromobacter sp., Aspergillus lentulus and Rhizopus arrhizus to degrade crude oil and pure hydrocarbon fractions, and these data are supported by the presence of the PMO and AlkB genes in the isolated microorganisms.

COVID-19 Associated Rhino-Orbital-Cerebral Mucormycosis: Clinical Features, Antifungal Susceptibility, Management and Outcome in a Tertiary Hospital in Iran.

Despite the unprecedented surge in the incidence of mucormycosis in the COVID-19 era, the antifungal susceptibility patterns (ASPs) of COVID-19 associated mucormycosis (CAM) isolates have not been investigated so far and it is unclear if the high mortality rate associated with CAM is driven by decreased susceptibility of Mucorales to antifungal drugs. To describe the clinical, mycological, outcome and in vitro ASPs of CAM cases and their etiologies from Iran. A prospective study from January 2020 to January 2022 at a referral tertiary hospital in Tehran, Iran was conducted for screening mucormycosis through histopathology and mycological methods. The identity of Mucorales isolates was revealed with ITS-panfungal PCR& sequencing and MALDI-TOF. The AS for amphotericin B, itraconazole, isavuconazole and posaconazole was cleared according to the EUCAST antifungal susceptibility testing protocol. A total of 150 individuals were diagnosed with CAM. Males constituted 60.7% of the population. The mean age was 54.9years. Diabetes was the leading risk factor (74.7%). The median interval between diagnosis of COVID-19 and CAM was 31days. The recovery rate of culture was as low as 41.3% with Rhizopus arrhizus being identified as the dominant (60; 96.7%) agent. Amphotericin B (MIC50 = 0.5µg/ml) demonstrated the highest potency against Mucorales. Majority of the cases had either diabetes, history of corticosteroid therapy or simultaneously both conditions. Accordingly, close monitoring of blood glucose should be considered. The indications for corticosteroids therapy are recommended to be optimized. Also, an anti Mucorales prophylaxis may be necessitated to be administrated in high risk individuals. Although amphotericin B was the most active agent, a higher rate of resistance to this antifungal was noted here in comparison with earlier studies on mucormycetes from non-CAM cases.

First report of leaf rot on Lonicera japonica caused by Rhizopus arrhizus in China.

Lonicera japonica is a perennial shrub that has been used since ancient times as a medicine to clear heat and detoxify poisons. Its branches (the vine of L. japonica) and unopened flower buds (honeysuckle) can be used as medicine to treat external wind heat or febrile disease fever (Shang, Pan, Li, Miao, & Ding, 2011). In July 2022, a serious disease was observed in L. japonica individuals planted in an area of experimental base of Nanjing Agricultural University (N 32°02', E 118°86'), Nanjing, Jiangsu Province, China. More than 200 Lonicera plants were surveyed, and the incidence of leaf rot in Lonicera leaves was over 80%. The initial symptoms were of chlorotic spots and gradual development of visible white mycelia and powdery substances (fungal spores) were observed on the leaves. Both the front and back of the leaves gradually appeared as brown diseased spots. Thus, a combination of multiple disease spots causes leaf wilting and the leaves eventually fall off. Leaves with typical symptoms were collected and cut into approximately 5 mm square fragments. The tissues were sterilized in 1% NaOCl for 90 s and 75% ethanol for 15 s and then washed with sterile water three times. The treated leaves were cultured on Potato Dextrose Agar (PDA) medium at 25℃. When mycelia grew around the leaf pieces, fungal plugs were collected along the outer edge of the colony and transferred to fresh PDA plates using a cork borer. Eight fungal strains with the same morphology were obtained after three rounds of subculturing. The colony was initially white with a fast growth rate, and occupied a 9-cm-diameter culture dish within 24 h. The colony turned gray-black in the later stages. After 2 days, small black sporangia spots appeared on top of the hyphae. The sporangia were yellow when immature, and black at maturity. The spores were oval with an average size of 29.6 (22.4-36.9) × 35.3 (25.8-45.2) µm (n = 50) in diameter. To identify the pathogen, fungal hyphae were scraped, and the fungal genome was extracted using a kit (BioTeke, Cat#DP2031). The internal transcribed spacer region (ITS) of the fungal genome was amplified with primers ITS1/ITS4, and the results of ITS sequencing were uploaded to the GenBank database with accession number OP984201. The phylogenetic tree was constructed using the neighbor-joining method with MEGA11 software. Phylogenetic analysis based on ITS showed that the fungus was grouped together with Rhizopus arrhizus (MT590591) and had high bootstrap support. Thus, the pathogen was identified as R. arrhizus. To verify Koch's postulates, 60 ml of a spore suspension (1×104 conidia/ml) was sprayed onto the surface of 12 healthy Lonicera plants, and the other 12 plants were sprayed with sterile water as a control. All plants were kept in the greenhouse at 25°C with 60% relative humidity. After 14 d, the infected plants showed symptoms similar to those of the original diseased plants. The strain was isolated again from the diseased leaves of artificially inoculated plants and verified as the original strain by sequencing. The results showed that R. arrhizus was the pathogen responsible for Lonicera leaf rot. Previous studies have shown that R. arrhizus causes garlic bulb rot (Zhang et al., 2022) and Jerusalem artichoke tuber rot (Yang et al., 2020). To our knowledge, this is the first report of R. arrhizus causing Lonicera leaf rot disease in China. Information regarding the identification of this fungus may be helpful for controlling the leaf rot disease.

MYCOFLORA OF FERMENTED LOCUST BEANS (Parkia biglobosa) SEED, “IRU” SOLD IN LOKOJA MARKETS, KOGI STATE, NIGERIA

Fermented locust beans are a popular nutritious food seasoning that are prone to microbial contamination due to unhygienic handling and improper storage. This research aimed to evaluate the mycological quality of locust beans sold in Lokoja markets, Kogi State, Nigeria. Thirty (30) samples of locust beans were collected from five different markets in Lokoja, analyzed for inherent fungi which were identified using standard mycological techniques. The results indicated variations in the mean fungal loads across the sampled markets. Old market had the highest mean fungal load (4.33 × 105 CFU/g), followed by Adankolo market (3.67 × 105 CFU/g) and Kpata market (3.0 × 105 CFU/g) while Lokongoma market had the lowest mean fungal load (2.0 × 105 CFU/g). The mean fungal load of the fermented locust beans from Old market was significantly different (p>0.05). A total of 55 fungal isolates that include: Aspergillus niger (29.1 %), Rhizopus arrhizus (25.5 %), Fusarium cladosporium (18.2 %), Fusarium cummunis (12.7 %), Aspergillus nudilans (9.1%), Aspergillus tamari (7.3 %) and Aspergillus terreus (1.8%) were obtained from the samples. Aspergillus niger, F. communis, F. clamadosporium and R. arrhizus were present in all the sampled markets, suggesting they are the predominant fermenter of locust beans. The presence of mycotoxigenic fungi in the locust beans seeds poses a significant public health risk. Therefore, it is important to ensure that locust beans are processed and stored under hygienic conditions at all times to safeguard consumer health.

DIAGNOSIS AND TREATMENT OF MUCORMYCOSIS: AN INTRUDER POST-COVID-19

Mucormycosis can be elaborated as mycosis due to Mucorales. Mucormycosis is an angioinvasive infection. Fungi of Mucorales order is the causative organism of mucormycosis and pertains to the class of zygomycetes. It is ordered on number third after candidiasis and aspergillosis in the category of invasive mycosis. Rhizopus arrhizus (oryzae) is the most important species which cause this disease. It is categorized as a disease with high mortality. There is a 46% chance of mucormycosis with person having sinus infection, 76% of chances with pulmonary infection, and 96% for disseminated Mucormycosis. The COVID-19 pandemic precipitated this disease in a common way. Around 90% of the population was exposed to coronavirus disease 2019 (COVID-19) infection during the pandemic which ultimately affected the immunity of individual, leading to increased chance of exposure to other infectious disease. Mucormycosis is one of such disease which can highly affect the individual with COVID-19 infection in patient’s history. This review presents a brief about the disease origin, occurrences, types, signs and symptoms, risk factors, diagnosis, and treatments available, along with recent patents. This review also elaborated the treatment of COVID-19-associated mucormycosis and other risk factors. It was found that the diagnosis is not simple and easy sometimes it was observed postmortem also. This review also focuses on various methods with which easy diagnosis of this dreadful disease can be done.

Innovative processes for the cultivation of mycromycete Fusarium gibbosum CNMN FD 12 and Rhizopus arrhizus CNMN FD 03 – producers of exocellular hydrolases

The optimal concentrations of the heterometallic compounds of “s” and “d” elements Sr, Ca and Fe with polydentate ligands based on 2,6-pyridinedicarboxyl chloride and the Schiff base -2,6-diacetylpyridine bis(picolinoylhydrazone) that increase the synthesis of exocellular proteases and lipases in micromycete Fusarium gibbosum CNMN FD 12 and Rhizopus arrhizus CNMN FD 03 were established. The obtained results were used in the development of 3 optimized mycelial mycelial fungal culture procedures (with alternative variants) that ensure enhanced proteolytic and lipolytic enzyme biosynthesis and shortened culture cycle, which provides opportunities for obtaining indigenous enzyme preparations based on local producing strains characterized by enhanced activity with predicted composition in short periods of time.

Safety evaluation of the food enzyme triacylglycerol lipase from the non-genetically modified Rhizopus arrhizus strain AE-TL(B).

The food enzyme triacylglycerol lipase (triacylglycerol acylhydrolase; EC 3.1.1.3) is produced with the non-genetically modified Rhizopus arrhizus strain AE-TL(B) by Amano Enzyme Inc. The food enzyme was considered free from viable cells of the production organism. It is intended to be used in the modification of fats and oils by interesterification and in the manufacture of enzyme-modified dairy ingredients. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 0.057 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1,960 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 34,386. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and no match found. The Panel considered that, under the intended conditions of use, the risk of allergic reactions upon dietary exposure cannot be excluded, but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Enrichment of Cd, Cr, Pb and Biological Detoxification Strategies in Sewage Irrigated Soils

Aim: Long-term use of sewage-sludge and improper management of agricultural lands can lead to an elevated heavy metal concentration in the soil resulting in barren soil. The present investigation was carried out to study the influence of different soil characteristics on the enrichment of Cd, Cr and Pb and their detoxification strategies in sewage irrigated soil profiles of Prayagraj region, India. Methodology: Di-acid mixture method used for soil analysis. The clean filtrate was used for the estimation of the heavy metals (Cd, Cr and Pb) by Atomic Absorption Spectrophotometer (AAS) (AAnalyst600, Perkin Elmer Inc., MA, USA). Isolation and identification of Cd, Cr and Pb Detoxifying microorganisms were isolated from the sewage-irrigated soils by nutrient agar medium. Results: It was observed that surface soils contained higher amount of DTPA- extractable heavy metals (Cd 3.00-3.20 mg kg-1,Cr 5.20-6.40 mg kg-1 and Pb 6.80-7.20 mg kg-1) and these amounts along with CEC (26.10 Cmol (p+) kg-1) and organic carbon (OC) Content (0.58%) decreased with the depth of soil profiles. Among the tested microorganisms, the highest accumulation of heavy metals in the sewage irrigated soils was observed in Citrobacter spp. to the extent of Cd 13.2%, Cr 36%, and Pb 42%. However, the lowest accumulation was observed in Escherichia coli to the extent of Cd 1.2%, Cr 8.4%, and Pb 10.2%. Conclusion: The horizons A of the studied soil profiles contain almost 12% more Cd, 9.11% more Cr, and 52% more Pb as compared to the contents of horizons B. Biological detoxification system metal uptake is largely influenced by the availability of metals. The highest accumulation of heavy metals was observed in the order of Pb > Cr > Cd by the selected microorganisms in the order of Citrobacter spp. >Bacillus spp. > Pseudomonas aerugia > Rhizopus arrhizus > Escherichia coli, resulting in the detoxification of the metals in the sewage irrigated soils. GRAPHICAL ABSTRACT

Isolate profiling and geographical distribution of COVID-19 associated mucormycosis cases presenting to a tertiary care hospital in Jodhpur, India

Background and PurposeCOVID-associated mucormycosis (CAM) was as a dreadful complication in India. The state of Rajasthan, reported remarkably more patients than others but the cause for such geographical variation was unclear. The demography, clinical presentation and pathogens of CAM were studied. MethodologyThis was a prospective observational study where tissue specimens from CAM patients were subjected to microscopy and culture. Results and conclusionOut of 324 suspected CAM patients, the diagnosis was proven in 215 cases (66.36%). Culture was positive in 51.63% patients. Rhizopus arrhizus was the most common mucorale (82.88%) and rhino-orbital-cerebral (95.37%) was most common clinical presentation.

Post-COVID-19 rhino-orbito-cerebral mucormycosis-A clinico-mycological study from North India.

The second wave of coronavirus disease 2019 (COVID-19), during the early 2021, lead to a devastating outbreak of mucormycosis in India. This study aimed to determine the aetiology, clinical features, comorbidities, and risk factors of rhino-orbito-cerebral mucormycosis (ROCM) and antifungal susceptibility pattern for the isolates. The study included all suspected cases of ROCM in post-COVID-19 patients attending the hospital from May to December 2021. A total of 70 patients were diagnosed with mucormycosis during the study period. The commonest presentations were rhino-orbital and rhino-orbito-cerebral in 35.7% of cases each. Diabetes mellitus was the commonest associated risk factor in 95.7% of all patients, while 78.5% of the patients were treated with corticosteroids in the recent past, and 25.7% presented with active COVID-19 pneumonia. The commonest isolate was Rhizopus arrhizus n = 14, followed by Aspergillus flavus n = 16, A. fumigatus n = 4, A. niger n = 3, Fusarium oxysporumn = 1, and Apophysomyces variabilisn = 1. Fungal species identification was done by phenotypic methods for all the isolates and DNA sequence analysis of 18 isolates, and antifungal susceptibility testing of 30 isolates was performed by commercially prepared HiMIC plate (HiMedia, Mumbai, India) using broth microdilution for amphotericin B, isavuconazole, itraconazole, voriconazole, and posaconazole. The MIC50 and MIC90 of amphotericin B for R. arrhizus strains were 0.25 and 4 μg/ml, respectively; and the MIC50 and MIC90 results for itraconazole, posaconazole, and isavuconazole were 8 and 8, 2 and 2, and 2 and 8 μg/ml, respectively. In vitro data showed that amphotericin B was the most effective antifungal against most species. The commercially available ready-to-use minimum inhibitory concentration plates are user-friendly for performing antifungal susceptibility, which may be useful in choosing appropriate regimens and monitoring emerging resistance.

Lactic Acid Produced by Wheat Straw Fermentation with Rhizopus Arrhizus Extends the Keeping Time of Fresh Poultry Meat

Lactic Acid Produced by Wheat Straw Fermentation with Rhizopus Arrhizus Extends the Keeping Time of Fresh Poultry Meat

Lactic Acid Produced by Wheat Straw Fermentation with Rhizopus Arrhizus Extends the Keeping Time of Fresh Poultry Meat

Lactic Acid Produced by Wheat Straw Fermentation with Rhizopus Arrhizus Extends the Keeping Time of Fresh Poultry Meat

Biotechnological Production of Fumaric Acid by Rhizopus arrhizus—Reaching Industrially Relevant Final Titers

Fumaric acid is used in various areas of the chemical industry due to its functional groups. For example, it is used in the polymer industry to produce unsaturated polyester resins, which are nowadays mostly produced from fossil raw materials. With regard to sustainable biotechnological fumaric acid production, the main challenge is to develop a cost-effective and robust fermentation process with industrially relevant final titers, productivities and yields. For biotechnological fumaric acid production, mainly fungi of the genus Rhizopus are used, which require very complex and challenging morphology control. The aim of this work is the development of an effective biotechnological fumaric acid production process with R. arrhizus NRRL 1526. Significant insights into the morphology control of the fungus and optimization of production characteristics were obtained, and a final titer of 86.3 g/L fumaric acid was achieved in a batch cultivation, with a yield of 0.67 g/g and a productivity of 0.60 g/(L∙h). In addition, a fed-batch process was developed, in which the production phase was extended, and a maximum final titer of 195.4 g/L fumaric acid was achieved. According to current knowledge, this value is the highest final concentration of fumaric acid produced using biotechnology.

Glycosylated heterocyles emulsified with antifungal fraction of Moringa oleifera for potentiation of mycolytic activity

To enhance the clinical effect of antifungal medications for treating deadly fungal infections there is an increasing demand for novel treatments. Exploration of multiple-drug targeting in antifungal therapeutics is the need of the present era. In this pursuit, we identified potent antifungal compounds that were directed towards the multiple virulent targets in Rhizopus arrhizus. Quinoxaline di-N-oxide and piperazine derivatives were identified to exhibit antifungal activities. 03 bioactive compounds were identified from the docking results and antifungal activity. Furthermore, these compounds which were combined with the alkaline extract of M. olifera to make the aqueous phase, an oil phase containing cinnamon oil or clove oil and a combination of surfactants was made to prepare a bioactive composite emulsion. A significant antimycotic activity was seen for the bioactive composite emulsion when compared with the clinically used antifungal drugs. Our results indicate the synergy and potentiation of antimycotic drugs based on integrative medicine.

Apophysomyces variabilis as an emerging pathogen in Mainland China.

Mucormycosis is a rare form of invasive, rapidly progressive and lethal opportunistic fungal infection caused by Mucorales. Although Rhizopus arrhizus (R. arrhizus) is the most commonly isolated Mucorales worldwide, infections caused by Apophysomyces variabilis (A. variabilis) are increasing. We present a case of necrotizing fasciitis caused by A. variabilis in an immunocompetent woman. In order to further understand the characteristics of the strain isolated from the patient, we identified the strain through ITS sequencing, assessed the ability to tolerate salt concentrations and temperature conditions, in addition to performing in vitro drug susceptibility testing against common antifungal agents. The strain showed 98.76% identity with A. variabilis in the NCBI database, and it was found to tolerate higher temperatures and salt concentrations than previously reported strains. The strain was sensitive to amphotericin B and posaconazole, but not to voriconazole, itraconazole, 5-fluorocytosine and echinocandins. This case indicates that Mucorales caused by A. variabilis should be recognised as an emerging pathogen that can cause a high mortality rate in the absence of prompt diagnosis and proper treatment in China, aggressive surgical debridement combined with prompt and appropriate antifungal treatment may improve outcomes.

Amphotericin B, itraconazole, posaconazole, and isavuconazole MICs against clinical Mucorales isolates obtained by visual inspection and spectrophotometric reading according to the EUCAST 9.4 procedure.

We compared the antifungal susceptibility of 92 Mucorales isolates obtained by visual inspection and spectrophotometric readings following EUCAST (European Committee on Antimicrobial Susceptibility Testing) testing. Amphotericin B minimum inhibitory concentrations (MICs) were up to 1 mg/l against most isolates and variable among species, except for Cunninghamella bertholletiae. Posaconazole MICs against most isolates were up to 1 mg/l and high against Mucor circinelloides, some Rhizopus arrhizus, and Rhizopus microsporus. Isavuconazole MICs ranged between 1 and 8 mg/l but were invariably>8 mg/l against M. circinelloides and C. bertholletiae. The agreement between MICs obtained by visual endpoint or spectrophotometric readings was moderate and higher when using the≥90% fungal growth inhibition endpoint.

DNA metabarcoding analysis of fungal community on surface of four root herbs

ObjectiveAngelicae Sinensis Radix (ASR, Danggui in Chinese), Cistanches Herba (CH, Roucongrong in Chinese), Ginseng Radix et Rhizoma (PG, Renshen in Chinese), and Panacis Quinquefolii Radix (PQ, Xiyangshen in Chinese), widely used as medicine and dietary supplement around the world, are susceptible to fungal and mycotoxin contamination. In this study, we aim to analyze their fungal community by DNA metabarcoding. MethodsA total of 12 root samples were collected from three main production areas in China. The samples were divided into four groups based on herb species, including ASR, CH, PG, and PQ groups. The fungal community on the surface of four root groups was investigated through DNA metabarcoding via targeting the internal transcribed spacer 2 region (ITS2). ResultsAll the 12 samples were detected with fungal contamination. Rhizopus (13.04%−74.03%), Aspergillus (1.76%−23.92%), and Fusarium (0.26%−15.27%) were the predominant genera. Ten important fungi were identified at the species level, including two potential toxigenic fungi (Penicillium citrinum and P. oxalicum) and eight human pathogenic fungi (Alternaria infectoria, Candida sake, Hyphopichia burtonii, Malassezia globosa, M. restricta, Rhizopus arrhizus, Rhodotorula mucilaginosa, and Ochroconis tshawytschae). Fungal community in ASR and CH groups was significantly different from other groups, while fungal community in PG and PQ groups was relatively similar. ConclusionDNA metabarcoding revealed the fungal community in four important root herbs. This study provided an important reference for preventing root herbs against fungal and mycotoxin contamination.

A Pipeline to Investigate Fungal-Fungal Interactions: Trichoderma Isolates against Plant-Associated Fungi.

Soil fungi play essential roles in ecosystems, forming complex interaction networks with bacteria, yeasts, other fungi, or plants. In the framework of biocontrol strategies, Trichoderma-based fungicides are at the forefront of research as an alternative to synthetic ones. However, the impact of introducing new microbial strain(s) on the soil microbiome of a habitat is not well-explored. Aiming to identify a quantitative method to explore the complex fungal interactions, we isolated twelve fungi from three Italian vineyards and identified three strains of the Trichoderma genus in addition to nine more plant-associated fungi of different genera. Investigating in dual nucleation assay fungal-fungal interactions, we recognised two types of interaction: neutral or antagonistic. All three Trichoderma strains displayed a slight inhibitory behaviour against themselves. Trichoderma strains showed a mutually intermingling growth with Aspergillus aculeatus and Rhizopus arrhizus but antagonistic behaviour against the plant pathogens Alternaria sp., Fusarium ramigenum, and Botrytis caroliniana. Yet, in some cases, antagonistic behaviour by Trichoderma fungi was also observed against plant-promoting fungi (e.g., Aspergillus piperis and Penicillium oxalicum). Our study highlights the importance of studying the interactions between fungi, aiming to clarify better the impact of fungal-based biological fungicides in the soil communities, and offers a pipeline for further applications.

Isolation and Identification of Fungi Associated with the Spoilage of Cocoyam Corms

Cocoyam (Colocasia esculenta) is an important tropical root crop grown purposely for its starchy corms. This study was carried out to isolate and identify fungi associated with the spoilage of cocoyam corms. These organisms were isolated from spoilt corms by direct inoculation of the rotten tissues on Sabouraud Dextrose Agar. The fungal isolates were identified using cultural and morphological features such as colony appearance and also through microscopic characteristics. The isolated organisms include Rhizopus stolonifera, Rhizopus arrhizus, Fusarium oxysporum, and Aspergillus niger. Out of the 70 samples that were analyzed, 45 (64%) had Rhizopus stolonifera, 36 (51%) had Fusarium oxysporum, 52 (74%) had Rhizopus arrhizus while 61 (87%) had Aspergillus niger. A pathogenicity test was carried out on healthy corms using isolated microorganisms. The result showed that the organisms were responsible for the deterioration of the corms. These organisms may have infected these corms through contaminated working tools during harvest or improper storage by farmers. Corms are always infected by molds if not properly handled or stored. Hence, proper care should be taken while harvesting, handling, or storing these corms to avoid being infected by these pathogenic organisms since they can be detrimental to human health. It can also cause huge economic losses to farmers.