Rhizopus Microsporus Research Articles

Cultivation of Arthrospira platensis and harvesting using edible fungi isolated from mould soybean cake

In this study, the cultivation and harvesting of Arthrospira platensis biomass were proposed via simple, safe, and efficient techniques for direct consumption. Cultivation of microalgae in a covered macrobubble column under outdoor conditions resulted in significant differences (p < 0.05) with a maximum dry cell weight (Xm) of 0.959 ± 0.046 g/L. Notably, outdoor cultures resulted in approximately twofold biomass compared to indoor cultures. This outcome shows that the developed outdoor setup integrated with solar panels while utilising Malaysia's weather and atmospheric air as carbon sources is viable. Meanwhile, for harvesting, the screening showed that the fungus isolated from mould soybean cake (tempeh) starter indicated the highest harvesting efficiency, which was then further identified as Rhizopus microsporus, microscopically and molecularly. Overall, the economical and portable setup of outdoor cultivation coupled with safe harvesting via locally isolated fungus from tempeh as a bioflocculant would provide sustainability to produce A. platensis biomass.

Microbiology Profile of COVID-19-Associated Rhino-Orbital Mucormycosis Pathogens in South India.

This study describes the microbiological and histopathological features of patients with COVID-19-associated rhino-orbital mucormycosis (ROM) seen at the L V Prasad Eye Institute between May and August 2021. Diagnosed clinically and radiologically, 24 patients with ROM were included in the study. Deep nasal swabs or endoscopically collected nasal swabs or orbital tissues were submitted for microbiological evaluation and invitro susceptibility testing by microbroth dilution for natamycin, amphotericin B, caspofungin, posaconazole, ketoconazole, and voriconazole. Cultures were processed by 28S ribosomal DNA polymerase chain reaction and molecular sequencing. A portion of orbital tissues was also sent for histopathological evaluation. The age of the patients ranged from 27 to 75 (mean 48.58 ± 14.09) years and the majority (79%) were male. Nineteen patients were known to be diabetic prior to developing ROM and 18 patients had recovered from active COVID-19 infection. Thirteen patients had a history of hospitalization during COVID-19 infection and eight received steroids. Of the 24 samples, microbiological evaluation identified Rhizopus arrhizus in 12, Rhizopus microsporus in 9, Lichtheimia ramosa in 2, and Rhizopus delemar in 1. Twelve isolates were tested for antifungal susceptibility and all were susceptible to natamycin and amphotericin B. The susceptibility to posaconazole was high, with minimum inhibitory concentration (MIC) < 2 µg/mL for 10/12 (84%) isolates, whereas the MIC of other drugs varied. Histopathological examination of tissues showed acute fulminant disease, granuloma formation, and vascular invasion by the fungal pathogens in these specimens. Rhizopus arrhizus was predominantly associated with ROM and most isolates were susceptible to amphotericin B and posaconazole. Further studies are needed to corroborate the findings and explain possible underlying links.

Fungal Biomarkers in Traditional Starter Determine the Chemical Characteristics of Turbid Rice Wine from the Rim of the Sichuan Basin, China.

The fungal community in Qu plays a key role in the formation of turbid rice wine (TRW) style. The Sichuan Basin and its surrounding areas have become one of the main TRW production regions in China; however, the fungal community in Qu and how they affect the characteristics of TRW remain unknown. Therefore, this study provided insight into the fungal biomarkers in Qu from Guang'an (GQ), Dazhou (DQ), Aba (AQ), and Liangshan (LQ), as well as their relationships with compounds in TRW. The main biomarkers in GQ were Rhizopus arrhizus, Candida glabrata, Rhizomucor pusillus, Thermomyces lanuginosus and Wallemia sebi. However, they changed to Saccharomycopsis fibuligera and Mucor indicus in DQ, Lichtheimia ramose in AQ, and Rhizopus microsporus and Saccharomyces cerevisiae in LQ. As a response to fungal biomarkers, the reducing sugar, ethanol, organic acids, and volatile compounds were also changed markedly in TRWs. Among important volatile compounds (VIP > 1.00), phenethyl alcohol (14.1-29.4%) was dominant in TRWs. Meanwhile, 3-methyl-1-butanol (20.6-56.5%) was dominant in all TRWs except that fermented by GQ (GW). Acetic acid (29.4%) and ethyl palmitate (10.1%) were dominant in GW and LW, respectively. Moreover, GQ biomarkers were positively correlated with acetic acid and all unique important volatile compounds in GW. DQ biomarkers had positive correlations with unique compounds of acetoin and ethyl 5-chloro-1,3,4-thiadiazole-2-carboxylate in DW. Meanwhile, the AQ biomarkers were positively correlated with all AW unique, important, and volatile compounds. Although there were not any unique volatile compounds in LW, 16 important volatile compounds in LW were positively related to LQ biomarkers. Obviously, biomarkers in different geographic Qu played vital roles in the formation of important volatile compounds, which could contribute specific flavor to TRWs. This study provided a scientific understanding for future efforts to promote the excellent characteristics of TRW by regulating beneficial fungal communities.

Complement, but Not Platelets, Plays a Pivotal Role in the Outcome of Mucormycosis In Vivo

Mucormycetes, a heterogeneous group of fungi, induce a life-threatening disease called mucormycosis. Immune deficiencies represent a major risk factor; hence, we wanted to illuminate the role of complement and platelets in the defense against mucormycetes. Rhizopus arrhizus (Ra), Rhizopus microsporus (Rm), Lichtheimia ramosa (Lr), Lichtheimia corymbifera (Lc), Rhizomucor pusillus (Rmp), and Mucor circinelloides (Mc) spores were opsonized with human and mouse serum, and C1q, C3c, and terminal complement complex (C5b-9) deposition was measured. Additionally, thrombocytopenic, C3-deficient, or C6-deficient mice were intravenously infected with selected isolates. Survival and immunological parameters were monitored, and fungal burden was determined and compared to that of immunocompetent and neutropenic mice. In vitro experiments showed significant differences in complement deposition between mucormycetes. Mc isolates bound up to threefold more human C5b-9 than other mucormycetes. Lr, Lc, and Mc bound high levels of murine C3c, whereas human C3c deposition was reduced on Mc compared to Lr and Lc. Murine C3c deposition negatively correlated with virulence. Complement deficiencies and neutropenia, but not thrombocytopenia, were shown to be a risk factor for a lethal outcome. Complement deposition varies between mucormycetes. Additionally, we demonstrated that complement and neutrophilic granulocytes, but not platelets, play an important role in a murine model of disseminated mucormycosis.

Mycetohabitans rhizoxinica in Patients with Rhinocerebral Mucormycosis Due to Rhizopus microsporus.

Mycetohabitans rhizoxinica in Patients with Rhinocerebral Mucormycosis Due to Rhizopus microsporus.

Stabilization of jiuyao quality for huangjiu brewing by fortifying functional strains based on core microbial community analysis

Jiuyao as a generally small saccharifying and spontaneously fermenting starter is indispensable for huangjiu brewing. However, jiuyao currently in use is facing a major challenge of standardized manufacturing because of its open operating environment and rather primitive operations. This study provided a stead manufacturing procedure for jiuyao by controlling the processing parameters. Saccharomycopsis fibuligera and Rhizopus microsporus were revealed as the core functional species related to starch-degrading enzyme activities with single-molecule real-time (SMRT) sequencing. Two strains with high starch-degrading abilities were successfully isolated and identified as Saccharomycopsis fibuligera CY2111 and Rhizopus microsporus SM4. Meanwhile, the environmental fermentation parameters of jiuyao were optimized to enhance enzyme activities. The glucoamylase and α-amylase activities of fortified jiuyao with strain CY2111 and SM4 were 3.07 and 3.15 times that of traditional jiuyao, respectively. Moreover, the alcohol content increased by approximately 7.5% when fortified jiuyao was used for huangjiu brewing. The flavor profiles determined by gas chromatography–mass spectrometry indicated there was no significant difference in the key aromas between the huangjiu fermented with fortified jiuyao and that of traditional jiuyao. Further, fortified jiuyao produced more pleasant esters in huangjiu such as ethyl isovalerate, isoamyl acetate, and ethyl caprylate. Combined with the sensory evaluation, huangjiu fermented with fortified jiuyao presented stronger fruity aroma. These results demonstrated that careful fermentation settings combined with biofortification technology were feasible to improve jiuyao quality, thus promoting huangjiu flavor. Taken together, it provided scientific guidance to improve traditional handcrafting and scale up the production of jiuyao under controllable fermentation.

Phenazine and quinolone are main compounds produced by Pseudomonas aeruginosa N1 during inhibitory interaction with Rhizopus microsporus

Phenazine and quinolone are main compounds produced by Pseudomonas aeruginosa N1 during inhibitory interaction with Rhizopus microsporus

Antioxidant activity of tempe fermented with three different &lt;i&gt;Rhizopus&lt;/i&gt; species

Tempe, a traditional Indonesian fermented soy-based food, reportedly has higher antioxidant activity than unfermented soybeans. In 2015, the Codex Alimentarius defined the starters of soybean tempe to be Rhizopus microsporus var. oligosporus, Rhizopus oryzae, and/or Rhizopus stolonifer. Most previous studies have focused only on tempe prepared with R. oligosporus. In this study, we compared the antioxidant activities of tempe fermented with three Rhizopus species and unfermented soybeans using assays for β-carotene bleaching (antioxidant activity), antioxidative potential, and oxidative stabilization. The β-carotene bleaching and antioxidative potential assays indicated that the tempe fermented with R. stolonifer had higher antioxidant activity than the tempe fermented with R. oligosporus and R. oryzae. We speculate that the high antioxidant properties of this product are attributable to the isoflavone aglycones and hydroxylated compounds produced by fermentation.

Symbiotic and toxinogenic Rhizopus spp. isolated from soils of different papaya producing regions in Mexico.

Mucoralean fungi from the genus Rhizopus are common inhabitants of terrestrial ecosystems, being some pathogens of animals and plants. In this study, we analyzed the symbiotic and toxinogenic potential of Rhizopus species derived from agricultural soils dedicated to the production of papaya (Carica papaya L.) in Mexico. Four representative strains of soil-derived Rhizopus spp. were analyzed employing molecular, microscopic, and metabolic methods. The ITS phylogenies identified the fungi as Rhizopus microsporus HP499, Rhizopus delemar HP475 and HP479, and Rhizopus homothallicus HP487. We discovered that R. microsporus HP499 and R. delemar HP475 harbor similar endofungal bacterial symbionts that belong to the genus Mycetohabitans (Burkholderia sensu lato) and that none of the four fungi were associated with Narnavirus RmNV-20S and RmNV-23S. Intriguingly, the interaction between R. delemar - Mycetohabitans showed different phenotypes from known R. microsporus - Mycetohabitans symbioses. Elimination of bacteria in R. delemar HP475 did not cause a detrimental effect on fungal growth or asexual reproduction. Moreover, metabolic and molecular analyses confirmed that, unlike symbiotic R. microsporus HP499, R. delemar HP475 does not produce rhizoxin, one of the best-characterized toxins produced by Mycetohabitans spp. The rhizoxin (rhi) biosynthetic gene cluster seems absent in this symbiotic bacterium. Our study highlights that the symbioses between Rhizopus and Mycetohabitans are more diverse than anticipated. Our findings contribute to expanding our understanding of the role bacterial symbionts have in the pathogenicity, biology and evolution of Mucorales.

WITHDRAWN

SESSION TITLE: COVID-19 Co-Infections SESSION TYPE: Rapid Fire Case Reports PRESENTED ON: 10/19/2022 12:45 pm - 1:45 pm INTRODUCTION: PAP is a rare entity that can occur secondary to infection, malignancy, or trauma. Mucormycosis in the setting of Covid-19 pneumonia has been increasingly recognized but PAP has only recently been reported in this setting. CASE PRESENTATION: A 44 year-old man with type 2 diabetes, non-ischemic cardiomyopathy, hypothyroidism, and ulcerative colitis presented with dyspnea and cough in July 2021. He was diagnosed with Covid-19 pneumonia and initially treated with molnupiravir. Eight days later he presented to the emergency room with worsening dyspnea, hypoxemia and diabetic ketoacidosis. He required 3L of oxygen and was intubated for airway protection. CT chest revealed mild bilateral patchy opacities and dexamethasone was started. Unfortunately, persistent fevers and worsening respiratory status ensued and repeat chest CT on hospital day (HD) 8 showed a new large left upper lobe (LUL) cavitary lesion. Cultures ultimately grew Rhizopus microsporus and he was started on amphotericin then isavuconazole after acute kidney injury developed. Dexamethasone was discontinued and interval imaging after ten days showed dramatic growth of the cavitary lesion (9 x 6 x 3 cm) with new extension through the chest wall, infiltrating the intercostal spaces and pectoralis muscle. Due to ventilator dependency a tracheostomy was performed on HD 24. Despite anti-fungal therapy the cavitary lesion persisted, with evidence of osseous destruction of the third and fourth ribs, as well as new fluid collections within the cavity and hilar extension. On HD 46 he was transferred to our institution for Thoracic Surgery and Interventional Radiology (IR) evaluations. Percutaneous drain placement followed by pneumonectomy vs. staged cavernostomy was considered; however, on HD 50, the patient suddenly developed massive hemoptysis. CTA of the chest showed a 1.6 x 1.5 cm PAP with active hemorrhage from the LUL anterior segmental artery with dispersion into the cavity. Urgent coil and glue embolization was successfully performed by IR. Ultimately, thoracic surgical intervention was deemed too high risk and thus he was medically managed with a regimen of isavuconazole, amphotericin, and terbinafine. Hemoptysis did not recur and he was eventually discharged from the hospital and liberated from both mechanical ventilation and tracheostomy. Chest CT 6 months from the initial diagnosis has shown stable to mildly decreased size of the cavitary lesion. DISCUSSION: This is the first case to our knowledge of PAP as a complication of Covid-19 and Mucor superinfection in the United States. Five cases of this combination have been recently reported in other countries. Risk factors for Mucor infection after Covid appear to be uncontrolled diabetes, DKA, and steroid administration. CONCLUSIONS: A high index of suspicion should be maintained in patients with these risk factors, as PAP can present as massive hemoptysis and is often fatal. Reference #1: Hoenigl M, Seidel D, Carvalho A, et al. The emergence of COVID-19 associated mucormycosis: a review of cases from 18 countries [ 2022 Jan 25]. Lancet Microbe. 2022;10.1016/S2666-5247(21)00237-8. doi:10.1016/S2666-5247(21)00237-8 Reference #2: Pruthi H, Muthu V, Bhujade H, et al. Pulmonary Artery Pseudoaneurysm in COVID-19-Associated Pulmonary Mucormycosis: Case Series and Systematic Review of the Literature. Mycopathologia. 2022;187(1):31-37. doi:10.1007/s11046-021-00610-9 Reference #3: Coffey MJ, Fantone J 3rd, Stirling MC, Lynch JP 3rd. Pseudoaneurysm of pulmonary artery in mucormycosis. Radiographic characteristics and management. Am Rev Respir Dis. 1992;145(6):1487-1490. doi:10.1164/ajrccm/145.6.1487 DISCLOSURES: No relevant relationships by Kevin Patel No relevant relationships by Clifford Sung

Volatile organic compounds mediated endogenous microbial interactions in Chinese baijiu fermentation

Microorganisms release abundant volatile organic compounds, and these compounds have important roles in distant interactions and communication. However, the effects of microbial volatile organic compounds on microbial interactions remains unclear in traditional food fermentations. In this study, we applied high-throughput sequencing analysis to reveal the structure and succession of microbial community in the preparations of Qu starter for Chinese baijiu fermentation. The genus Weissella, Pediococcus, Lactobacillus, Saccharomycopsis, Saccharomyces, Candida and Rhizopus were dominant and varied in this preparation, and the abundant Rhizopus had a positive correlation with Lactobacillus in situ system. In addition, benzyl alcohol produced by Rhizopus microsporus could significantly promote the growth of Lactobacillus fermentum in a simulative baijiu fermentation under laboratory. Moreover, the addition of benzyl alcohol could enhance the activation of alanine, aspartate and glutamate metabolism and arginine biosynthesis for promoting the growth of Lactobacillus fermentum through transcriptional analysis. Therefore, this study revealed volatile organic compounds from microorganisms could meditate the endogenous microbial interactions in Chinese baijiu fermentation. Furthermore, it provides a potential approach to add or remove volatile organic compounds to regulate the microbial interactions, for improving traditional food fermentations.

P169 Systemic Pythiosis: presumably, the first human case in India

Poster session 2, September 22, 2022, 12:30 PM - 1:30 PMObjectivesThis is the first human case of systemic disease due to Pythium insidiosum reported from India. The case highlights difficulty in diagnosis and management.MethodsA 44-year-old male patient had a peri-esophageal and peri-gastric inflammatory lesion which showed inflammation along with sparsely septate hyphae (Fig. 1), and partially responded to voriconazole (VCZ). After 1.5 years, he developed a massive liver lesion (Fig. 2), and hepatic venous thrombosis which was refractory despite restarting therapy with posaconazole (PCZ). As a desperate measure, surgical excision of the large liver lesion was undertaken.ResultsSerum BDG was positive and Serum Galactomannan was negative. There was no tidy explanation for the insidious clinical course of the illness over 1.5 years, partial response to VCZ for the esophageal lesion and inadequate response of the subsequent lesion to PCZ. The liver biopsy specimen showed a flat, feathery growth on SDA which was identified at PGI, Chandigarh by ITS as P. insidiosum. P. insidiosum and additionally Rhizopus microsporus were identified by molecular sequencing from the surgical specimen as well. The patient succumbed to carbapenem-resistant Klebsiella bacteremia in the postoperative stage.ConclusionThe case underscores the insidious course of systemic pythiosis, diagnostic, and management challenges.

Rhizopus microsporus pulmonary sepsis: Case report and review of literature

The incidence of opportunistic fungal infection, mucormycosis associated with high mortality rate is steadily increasing. Pulmonary mucormycosis though rare, it relatively affects individuals with diabetes mellitus and other immunosuppressive conditions. The present study reports on case of pulmonary mucormycosis caused by Rhizopus microsporus. Sputum sample was collected from a 47-year-old male with diagnosed with tuberculosis with spontaneous left sided pneumothorax and diabetes mellitus. The positive fungal culture was characterized by phenotypic and genotypic methods and antifungal susceptibility of the isolate was tested against azoles and amphotericin B. The etiological agent was identified as R. microsporus based on phenotypic features and molecular sequencing of ITS. The isolate was susceptible to all the tested antifungal and the patient responded well to Amphotericin B with strict glycemic control and combination of anti-infective therapy. Though pulmonary mucormycosis is relatively rare; it share its clinical picture with pulmonary tuberculosis and aspergillosis, hence clinical suspicion for mucormycosis in susceptible high risk patients is warranted for early diagnosis and appropriate therapy.

Evaluation of environmental Mucorales contamination in and around the residence of COVID-19-associated mucormycosis patients.

IntroductionRecently, India witnessed an unprecedented surge of coronavirus disease 2019 (COVID-19)-associated mucormycosis (CAM) cases. In addition to patient management issues, environmental Mucorales contamination possibly contributed to the outbreak. A recent study evaluated environment contamination by Mucorales in the hospital setting. However, a considerable number of CAM patients were never admitted to a hospital before the development of the disease. The present study, therefore, planned to evaluate Mucorales contamination of patients’ residences.MethodsThe residential environment of 25 patients with CAM living in north India was surveyed. Air samples were collected from indoor and immediate outdoor vicinity of the patients’ residence and cultured on Dichloran Rose–Bengal Chloramphenicol (DRBC) agar with benomyl for selective isolation of Mucorales. Surface swab samples were also collected from the air coolers fitted in those residences and cultured on DRBC agar. The isolates were identified by phenotypic and genotypic methods. Amplified fragment length polymorphism (AFLP) was employed to evaluate the genetic relatedness of the environmental and patients’ clinical isolates.ResultsThe median spore count (mean ± SD, cfu/m3) of Mucorales in the air of patients’ bedrooms was significantly higher than in the air in other rooms in those residences (3.55 versus 1.5, p = 0.003) or the air collected directly from the front of the air cooler (p < 0.0001). The Mucorales spore count in the environment did not correlate with either ventilation of the room or hygiene level of the patients’ residences. Rhizopus arrhizus was isolated from the environment of all patients’ residences (n = 25); other Mucorales species isolated were Cunninghamella bertholletiae (n = 14), Rhizopus microsporus (n = 6), Rhizopus delemar (n = 6), Syncephalastrum racemosum (n = 1), Lichtheimia corymbifera (n = 1), and Mucor racemosus (n = 1). Genetic relatedness was observed between 11 environmental isolates from the patients’ bedrooms and respective clinical isolates from patients.DiscussionThe study supported the view that the patients might have acquired Mucorales from the home environment during the post-COVID-19 convalescence period. Universal masking at home during patients’ convalescence period and environmental decontamination could minimize exposure in those susceptible patients.

A highly conserved gene locus in endofungal bacteria codes for the biosynthesis of symbiosis-specific cyclopeptides.

The tight association of the pathogenic fungus Rhizopus microsporus and its toxin-producing, bacterial endosymbionts (Mycetohabitans spp.) is distributed worldwide and has significance for agriculture, food production, and human health. Intriguingly, the endofungal bacteria are essential for the propagation of the fungal host. Yet, little is known about chemical mediators fostering the symbiosis, and universal metabolites that support the mutualistic relationship have remained elusive. Here, we describe the discovery of a complex of specialized metabolites produced by endofungal bacteria under symbiotic conditions. Through full genome sequencing and comparative genomics of eight endofungal symbiont strains from geographically distant regions, we discovered a conserved gene locus (hab) for a nonribosomal peptide synthetase as a unifying trait. Bioinformatics analyses, targeted gene deletions, and chemical profiling uncovered unprecedented depsipeptides (habitasporins) whose structures were fully elucidated. Computational network analysis and labeling experiments granted insight into the biosynthesis of their nonproteinogenic building blocks (pipecolic acid and β-phenylalanine). Deletion of the hab gene locus was shown to impair the ability of the bacteria to enter their fungal host. Our study unveils a common principle of the endosymbiotic lifestyle of Mycetohabitans species and expands the repertoire of characterized chemical mediators of a globally occurring mutualistic association.

Bioconversion of Jackfruit Seed Waste to Fungal Biomass Protein by Submerged Fermentation.

The bioconversion of jackfruit seed into a valuable product like Single-Cell Protein (SCP) was carried out using Generally Recognized As Safe (GRAS), five filamentous fungi such as Penicillium expansum, Aspergillus niger, Aspergillus oryzae, Rhizopus microsporus, and Candida intermedia by submerged fermentation. Data obtained from the study showed that supplementation of jackfruit seed extracts with inorganic nitrogen sources and glucose as a carbon source enhanced fungal biomass and SCP production. Among the various fungal strains, A. niger gave the highest biomass and protein yield of 4.01 ± 0.07g/l and 1.82 ± 0.03g/l, respectively, on the 9th day of fermentation followed by P. expansum (3.65 ± 0.04g/l and 1.68 ± 0.03g/l, respectively). C. intermedia growth was not recorded in all the experimental media. The present study revealed that fungal biomass has shown low crude fat, crude fiber, and total genomic DNA content ranged from 1.10 ± 0.20 to 4.95 ± 0.40%. A. niger and P. expansum were the most efficient in the conversion of sugar (55.83 ± 0.3% and 54.71 ± 0.4%, respectively) to yield biomass in sugar supplementation media. P. expansum and A. niger were the most promising fungal strains to produce fungal biomass protein using inexpensive agro-waste materials.

Proteomic analysis of a copper mine isolated fungus Rhizopus microspores IOC 4686 when exposed to copper sulfate

The fungus Rhizopus microsporus, known for its absorption capacity for toxic metals was used to understand the green metal recovery via analysis of its physiology under metal stress conditions through proteomic methods. To investigate the effects of copper stress on fungus, R. microsporus IOC 4686, isolated from the mine environment, was exposed to copper ions (50mgL-1) for 48 h. This study was performed only on copper exposure. Tryptic and chymotryptic extracts of proteins were analyzed by nano- liquid chromatography-tandem mass spectrometry, identification was performed by PEAKS Studio 8.5. Proteins were classified according to their molecular function and biological process. Enzymes, such as catalase, superoxide dismutase, and cytochrome c peroxidase were found in the presence and absence of copper ions. However, only in presence of copper ions, was observed the presence of heat shock proteins (HPS 20, HPS 70, and HPS 78) and metalloproteins (GrpE protein homolog and cytochrome P450). These classes of proteins have been produced by cells in response to stress conditions. The control group (absence of copper ions) also presented antioxidant enzymes suggesting that the fungus isolated from the mine environment already has adapted to the copper. The presence of these proteins suggested a physiological response of R. microsporus IOC 4686 to oxidative stress induced by copper.

Evaluation of the Vitek Ms system for the identification of filamentous fungi.

The use of MALDI-TOF for fungal identification remains a challenge. In this study, using a commercial protein extraction kit and updated database, VITEK MS system was able to identify up to 89.0% of a diverse collection of 200 filamentous fungi representing 43 fungal species.

A bacterial endosymbiont of the fungus Rhizopus microsporus drives phagocyte evasion and opportunistic virulence

SummaryOpportunistic infections by environmental fungi are a growing clinical problem, driven by an increasing population of people with immunocompromising conditions. Spores of the Mucorales order are ubiquitous in the environment but can also cause acute invasive infections in humans through germination and evasion of the mammalian host immune system. How they achieve this and the evolutionary drivers underlying the acquisition of virulence mechanisms are poorly understood. Here, we show that a clinical isolate of Rhizopus microsporus contains a Ralstonia pickettii bacterial endosymbiont required for virulence in both zebrafish and mice and that this endosymbiosis enables the secretion of factors that potently suppress growth of the soil amoeba Dictyostelium discoideum, as well as their ability to engulf and kill other microbes. As amoebas are natural environmental predators of both bacteria and fungi, we propose that this tri-kingdom interaction contributes to establishing endosymbiosis and the acquisition of anti-phagocyte activity. Importantly, we show that this activity also protects fungal spores from phagocytosis and clearance by human macrophages, and endosymbiont removal renders the fungal spores avirulent in vivo. Together, these findings describe a new role for a bacterial endosymbiont in Rhizopus microsporus pathogenesis in animals and suggest a mechanism of virulence acquisition through environmental interactions with amoebas.

Pseudomonas indica-Mediated Silver Nanoparticles: Antifungal and Antioxidant Biogenic Tool for Suppressing Mucormycosis Fungi.

Mucormycosis is considered one of the most dangerous invasive fungal diseases. In this study, a facile, green and eco-friendly method was used to biosynthesize silver nanoparticles (AgNPs) using Pseudomonas indica S. Azhar, to combat fungi causing mucormycosis. The biosynthesis of AgNPs was validated by a progressive shift in the color of P. indica filtrate from colorless to brown, as well as the identification of a distinctive absorption peak at 420 nm using UV-vis spectroscopy. Fourier-transform infrared spectroscopy (FTIR) results indicated the existence of bioactive chemicals that are responsible for AgNP production. AgNPs with particle sizes ranging from 2.4 to 53.5 nm were discovered using transmission electron microscopy (TEM). Pattern peaks corresponding to the 111, 200, 220, 311, and 222 planes, which corresponded to face-centered cubic forms of metallic silver, were also discovered using X-ray diffraction (XRD). Moreover, antifungal activity measurements of biosynthesized AgNPs against Rhizopus Microsporus, Mucor racemosus, and Syncephalastrum racemosum were carried out. Results of antifungal activity analysis revealed that the biosynthesized AgNPs exhibited outstanding antifungal activity against all tested fungi at a concentration of 400 µg/mL, where minimum inhibitory concentrations (MIC) were 50, 50, and 100 µg/mL toward R. microsporus, S. racemosum, and M. racemosus respectively. In addition, the biosynthesized AgNPs revealed antioxidant activity, where IC50 was 31 µg/mL when compared to ascorbic acid (0.79 µg/mL). Furthermore, the biosynthesized AgNPs showed no cytotoxicity on the Vero normal cell line. In conclusion, the biosynthesized AgNPs in this study can be used as effective antifungals with safe use, particularly for fungi causing mucormycosis.