Marine Fungal Strains Research Articles

Fungal carbonatogenesis process mediates zinc and chromium removal via statistically optimized carbonic anhydrase enzyme

IntroductionWith rapid elevation in population, urbanization and industrialization, the environment is exposed to uncontrolled discharge of effluents filled with broad-spectrum toxicity, persistence and long-distance transmission anthropogenic compounds, among them heavy metals. That put our ecosystem on the verge or at a stake of drastic ecological deterioration, which eventually adversely influence on public health. Therefore, this study employed marine fungal strain Rhodotorula sp. MZ312369 for Zn2+ and Cr6+ remediation using the promising calcium carbonate (CaCO3) bioprecipitation technique, for the first time.ResultsInitially, Plackett–Burman design followed by central composite design were applied to optimize carbonic anhydrase enzyme (CA), which succeeded in enhancing its activity to 154 U/mL with 1.8-fold increase comparing to the basal conditions. The potentiality of our biofactory in remediating Zn2+ (50 ppm) and Cr6+ (400 ppm) was monitored through dynamic study of several parameters including microbial count, CA activity, CaCO3 weight, pH fluctuation, changing the soluble concentrations of Ca2+ along with Zn2+ and Cr6+. The results revealed that 9.23 × 107 ± 2.1 × 106 CFU/mL and 10.88 × 107 ± 2.5 × 106 CFU/mL of cells exhibited their maximum CA activity by 124.84 ± 1.24 and 140 ± 2.5 U/mL at 132 h for Zn2+ and Cr6+, respectively. Simultaneously, with pH increase to 9.5 ± 0.2, a complete removal for both metals was observed at 168 h; Ca2+ removal percentages recorded 78.99% and 85.06% for Zn2+ and Cr6+ remediating experiments, respectively. Further, the identity, elemental composition, functional structure and morphology of bioremediated precipitates were also examined via mineralogical analysis. EDX pattern showed the typical signals of C, O and Ca accompanying with Zn2+ and Cr6+ peaks. SEM micrographs depicted spindle, spherical and cubic shape bioliths with size range of 1.3 ± 0.5–23.7 ± 3.1 µm. Meanwhile, XRD difractigrams unveiled the prevalence of vaterite phase in remediated samples. Besides, FTIR profiles emphasized the presence of vaterite spectral peaks along with metals wavenumbers.ConclusionCA enzyme mediated Zn2+ and Cr6+ immobilization and encapsulation inside potent vaterite trap through microbial biomineralization process, which deemed as surrogate ecofriendly solution to mitigate heavy metals toxicity and restrict their mobility in soil and wastewater.

Metabolite profiles of Paragliomastix luzulae (formerly named as Acremonium striatisporum) KMM 4401 and its co-cultures with Penicillium hispanicum KMM 4689

The marine holothurian-derived fungal strain KMM 4401 has been identified as Paragliomastix luzulae using 28S rDNA, ITS regions and the partial TEF1 gene sequences. The metabolite profile of the fungal culture was studied by UPLC-MS technique. The strain KMM 4401 is a source of various virescenoside-type isopimarane glycosides suggested as chemotaxonomic feature for this fungal species. Also Px. luzulae KMM 4401 was proposed as possible source of new bioactive secondary metabolites especially antimicrobials. Moreover, the co-cultures of Px. luzulae KMM 4401 with another marine fungus Penicillium hispanicum KMM 4689 inoculated simultaneously or after two weeks were investigated by same way. It was shown, that P. hispanicum KMM 4689 suppressed the production of most of Px. luzulae KMM 4401 metabolites. On the other hand, the co-cultivation of P. hispanicum KMM 4689 and Px. luzulae KMM 4401 resulted in increasing of production of main deoxyisoaustamide alkaloids of P. hispanicum KMM 4689 on 50–190%.Graphical

Process optimization for the production of fibrinolytic enzyme by a novel marine fungus – Penicillium steckii KU1

The demand for microbial thrombolytic agents is alarmingly increasing, and the discovery of novel microbial species with significant level of fibrinolytic enzyme production are required to cope up with the current circumstances. Surprisingly, marine fungi remain largely unexplored in this regard, presenting an untapped potential for the production of fibrinolytic enzymes.A novel marine fungal strain (Penicillium steckii KU1) was isolated successfully from Kappil beach, Kerala. At the beginning Czapek-dox media was used for the production of fibrinolytic enzyme. Statistical optimization of the enzyme production was achieved initially by Plackett-Burman design (PB). Interactive effect of various process parameters was further scrutinized by Central Composite Design (CCD). Incubation time, inoculum size and concentration of casein were shown significant contribution towards production. Statistical optimization, resulted in a tenfold increment (454.49 ± 14.66 U/mL) [optimized conditions - 30 °C, pH 7, casein 2.7 % (w/v), inoculum 5.75 million spores/mL and 115 h incubation], against the predicted value 441.42 U/mL.

UTILIZATION OF MANGROVE ENDOPHYTIC FUNGI AS A SUSTAINABLE AND ENVIRONMENTALLY FRIENDLY SOURCE OF CHITOSAN

Chitosan is an important biopolymer that is used as a raw material in several industries, but the manufacturing process has the potential to harm the environment. This study aimed to exploit chitosan in mangrove endophytic fungi and to characterize it. The four fungi isolates used were 20BB0501, 20CB07, 20BA04, and 20BA0502. Fungi were obtained from mangrove plants and identified macroscopically and microscopically using the coverslip method. After performing fungal maintenance on MEA media, fungi cultivation was done on rice media for 14 days. A chitosan extract was made by isolating and extracting the chitosan from the fungal biomass. FTIR was used to characterize the isolated chitosan extract. Macroscopic examinations revealed that each of the four strains had a delicate structure and was white. According to the extraction results, the yield of chitosan from the fungal biomass was 7.5%, 16.7%, 1.6%, and 11%, respectively. According to the FTIR data, showed the degree of deacetylation reached 85.02%, 97.78%, 88.7%, and 85.02%. It can be concluded that mangrove endophytic fungi can be used in the manufacture of chitosan, which produces a high degree of deacetylation using a more environmentally friendly process. The results of this study indicate that marine fungal strains can be used as a source of chitosan. This basis can be developed for the production of bio surfactants, enzymes, and the discovery of new bioactive compounds has pharmacological and biotechnological potential.

Release of cell-free enzymes by marine pelagic fungal strains.

Fungi are ubiquitous organisms that secrete different enzymes to cleave large molecules into smaller ones so that can then be assimilated. Recent studies suggest that fungi are also present in the oceanic water column harboring the enzymatic repertoire necessary to cleave carbohydrates and proteins. In marine prokaryotes, the cell-free fraction is an important contributor to the oceanic extracellular enzymatic activities (EEAs), but the release of cell-free enzymes by marine fungi remains unknown. Here, to study the cell-free enzymatic activities of marine fungi and the potential influence of salinity on them, five strains of marine fungi that belong to the most abundant pelagic phyla (Ascomycota and Basidiomycota), were grown under non-saline and saline conditions (0 g/L and 35 g/L, respectively). The biomass was separated from the medium by filtration (0.2 μm), and the filtrate was used to perform fluorogenic enzymatic assays with substrate analogues of carbohydrates, lipids, organic phosphorus, sulfur moieties, and proteins. Kinetic parameters such as maximum velocity (Vmax) and half-saturation constant (Km) were obtained. The species studied were able to release cell-free enzymes, and this represented up to 85.1% of the respective total EEA. However, this differed between species and enzymes, with some of the highest contributions being found in those with low total EEA, with some exceptions. This suggests that some of these contributions to the enzymatic pool might be minimal compared to those with higher total EEA. Generally, in the saline medium, the release of cell-free enzymes degrading carbohydrates was reduced compared to the non-saline medium, but those degrading lipids and sulfur moieties were increased. For the remaining substrates, there was not a clear influence of the salinity. Taken together, our results suggest that marine fungi are potential contributors to the oceanic dissolved (i.e., cell-free) enzymatic pool. Our results also suggest that, under salinity changes, a potential effect of global warming, the hydrolysis of organic matter by marine fungal cell-free enzymes might be affected and hence, their potential contribution to the oceanic biogeochemical cycles.

Evidence of Small Fungal Cysteine-Rich Proteins Acting as Biosurfactants and Self-Assembling into Large Fibers.

Fungi produce surface-active proteins, among which hydrophobins are the most characterized and attractive also for their ability to form functional amyloids. Our most recent findings show that these abilities are shared with other classes of fungal proteins. Indeed, in this paper, we compared the characteristics of a class I hydrophobin (Vmh2 from Pleurotus ostreatus) and an unknown protein (named PAC3), extracted from the marine fungal strain Acremonium sclerotigenum, which does not belong to the same protein family based on its sequence features. They both proved to be good biosurfactants, stabilizing emulsions in several conditions (concentration, pH, and salinity) and decreasing surface tension to a comparable value to that of some synthetic surfactants. After that, we observed for both Vmh2 and PAC3 the formation of giant fibers without the need for harsh conditions or long incubation time, a remarkable ability herein reported for the first time.

Enzymatic bromination of marine fungal extracts for enhancement of chemical diversity

This study reports for the first time the use of a vanadium chloroperoxidase (vCPO) enzyme to increase the chemical diversity of marine fungal extracts to generate new natural chemical entities. The vCPO used is a recombinant protein from the marine fungus Hortaea werneckii (HwvCPO). It catalyzes the formation of hypohalous acid (HOX), a highly reactive compound that can react with electron-rich substrates. Here, four fungal extracts obtained from different marine fungal strains (Penicillium expansum, Aspergillus pseudoglaucus, Trichoderma sp. and Hortaea werneckii) were investigated for enhancement of their chemical diversity. The metabolomic study showed that the enzymatic treatment of extracts of P. expansum and A. pseudoglaucus significantly boosted the chemodiversity by increasing the number of halogenated molecules. Indeed, respectively 5.07 and 6.65 times more halogenated ions were detected in ESI-MS profile of the extracts compared to negative controls. The new chemistry generated allowed the identification of new brominated compounds, one of which was further purified and characterized as 12-bromo-communesin A (2). This new compound, in contrast to communesin A (1), exhibited moderate antimicrobial activity on the methillicin-resistant Staphylococcus aureus (IC50 of 62 μM). This study has clearly demonstrated the employment of the vCPO enzyme to be a promising and environmentally friendly strategy to enhance the chemical diversity of natural extracts.

Screening of antibacterial and antioxidant activities of marine fungi isolated from the North Sea of Vietnam

Marine fungi are recognized as a rich source of pharmacologically active secondary metabolites, different from terrestrial fungi. This study aimed to assess the antimicrobial and antioxidant activities of 61 marine fungal strains isolated from 34 samples collected in the research journey of the Akademik Oparin vessel in the North Sea of Vietnam in 2021. Of these, 23 were from sponges, 21 from seaweeds, 15 from sediments, and only 2 from seawater. The antimicrobial screening results showed that 75.4% (n = 46) of fungal strains exhibited inhibitory activity against at least one test microorganism. The antioxidative properties results indicated the capacity for free DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging of crude extracts with 32.7% (n = 20) and 93.4% (n = 57), respectively. Six isolates with potent antibiotic and antioxidant activities were identified as belonging to the phylum Ascomycota and affiliated with five genera. Our findings indicated that these marine fungi could be impressive sources of multi-functional bioactive compounds and may find applications in the pharmaceutical industry.

The screening for marine fungal strains with high potential in alkaloids production by in situ colony assay and LC-MS/MS based secondary metabolic profiling.

Alkaloids are the second primary class of secondary metabolites (SMs) from marine organisms, most of which have antioxidant, antitumor, antibacterial, anti-inflammatory, and other activities. However, the SMs obtained by traditional isolation strategies have drawbacks such as highly reduplication and weak bioactivity. Therefore, it is significantly important to establish an efficient strategy for screening strains and mining novel compounds. In this study, we utilized in situ colony assay combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify the strain with high potential in alkaloids production. The strain was identified by genetic marker genes and morphological analysis. The secondary metabolites from the strain were isolated by the combine use of vacuum liquid chromatography (VLC), ODS column chromatography, and Sephadex LH-20. Their structures were elucidated by 1D/2D NMR, HR-ESI-MS, and other spectroscopic technologies. Finally, these compounds bioactivity were assay, including anti-inflammatory and anti-β aggregation. Eighteen marine fungi were preliminarily screened for alkaloids production by in situ colony assay using Dragendorff reagent as dye, and nine of them turned orange, which indicated abundant alkaloids. By thin-layer chromatography (TLC), LC-MS/MS, and multiple approaches assisted Feature-Based Molecular Networking (FBMN) analysis of fermentation extracts, a strain ACD-5 (Penicillium mallochii with GenBank accession number OM368350) from sea cucumber gut was selected for its diverse alkaloids profiles especially azaphilones. In bioassays, the crude extracts of ACD-5 in Czapek-dox broth and brown rice medium showed moderate antioxidant, acetylcholinesterase inhibitory, anti-neuroinflammatory, and anti-β aggregation activities. Three chlorinated azaphilone alkaloids, compounds 1-3 (sclerotioramine, isochromophilone VI, and isochromophilone IX, respectively), were isolated from the fermentation products of ACD-5 in brown rice medium guided by bioactivities and mass spectrometry analysis. Compound 1 had shown remarkable anti-neuroinflammatory activity in liposaccharide induced BV-2 cells. In summary, in situ colony screening together with LC-MS/MS, multi-approach assisted FBMN can act as an efficient screening method for strains with potential in alkaloids production.

Novel polyketide from Fusarium verticillioide G102 as NPC1L1 inhibitors

One novel polyketide, fusaritide A (1), was isolated from a marine fish-derived halotolerant fungal strain Fusarium verticillioide G102. The structure was determined through extensive spectroscopic analysis and high-resolution electrospray ionization mass spectrometry. Fusaritide A (1) with unprecedented structure reduced cholesterol uptake by inhibiting Niemann-Pick C1-Like 1 (NPC1L1).

Fungal Metabarcoding Data for Two Grapevine Varieties (Regent and Vitis vinifera ‘Cabernet-Sauvignon’) Inoculated with Powdery Mildew (Erysiphe necator) Under Drought Conditions

Fungal Metabarcoding Data for Two Grapevine Varieties (Regent and <i>Vitis vinifera</i> ‘Cabernet-Sauvignon’) Inoculated with Powdery Mildew (<i>Erysiphe necator</i>) Under Drought Conditions

New and bioactive polyketides from Hawaiian marine-derived fungus Trichoderma sp. FM652

Two new sorbicillinoid derivatives (1 and 2), together with ten other related compounds (3–12) were isolated from a Hawaiian marine fungal strain Trichoderma sp. FM652. The structures of compounds 1 and 2, including the absolute configuration, were elucidated by extensive analysis of NMR spectroscopy, HRESIMS and electronic circular dichroism (ECD) data. Compounds 6–12 exhibited significant anti-proliferative activity against ovarian cancer cell line A2780, with the IC50 values ranging from 0.5 to 8.07 μM. Moreover, compounds 1, 7 and 8 showed significant inhibition against NF-κB with IC50 values of 13.83, 24.40 and 14.63 µM, respectively. Compounds 6, 9 and 12 also demonstrated moderate inhibitory activity against S. aureus and methicillin resistant S. aureus with the MIC values in the range of 10–40 μg/mL.

Antibacterial metabolites from an unexplored strain of marine fungi Emericellopsis minima and determination of the probable mode of action against Staphylococcus aureus and methicillin-resistant S. aureus.

Increasing prevalence of drug resistance has led researchers to focus on discovering new antibacterial agents derived from the marine biome. Although ample studies have investigated marine fungi for their bioactive metabolites with hopeful prospects in drug discovery. The present study was aimed to isolate/ identify potential antimethicillin-resistant Staphylococcus aureus compounds producing marine fungal strain from the Indian marine environment. The effective anti-MRSA compound was produced by a marine fungal strain designated as D6. The D6 strain exhibited 99% similarity to Emericellopsis minima based on 18S rRNA gene analysis. The culture conditions of E. minima D6 were optimized using nutritional and environmental parameters for enhanced anti-MRSA compound production. The agar well diffusion assay was used to determine the inhibition zone diameter of the crude extract against S. aureus and methicillin-resistant S. aureus, whereas the broth microdilution method was used to determine their minimum inhibitory concentration (MIC) active fraction. MIC values of the ethyl acetate fraction ranged from 0.8 to 1 mg/mL. SEM analysis revealed that the ethyl acetate fraction induces deep craters in methicillin-resistant S. aureus. Further, GC-MS analysis confirmed the occurrence of a total of 15 major compounds in active ethyl acetate fraction. Some of the major antibacterial compounds included cyclopentanol, isothiazole, benzoic acid, pyrrolo[1,2-a] pyrazine-1,4-dione, and hexahydro. These findings suggest that the marine fungi of E. minima can be a valuable candidate for prospecting antibiotics and an alternative complementary strategy for drug-resistant bacterial infections.

Anti-neuroinflammatory effect of oxaline, isorhodoptilometrin, and 5-hydroxy-7-(2'-hydroxypropyl)-2-methyl-chromone obtained from the marine fungal strain Penicillium oxalicum CLC-MF05.

Penicillium is a rich source of bioactive compounds. Among all Penicillium species, Penicillium oxalicum has been reported to produce various types of secondary metabolites, including alkaloids, phenolics, and tetrahydroxanthone dimeric compounds, exhibiting many pharmacological effects, such as antiviral, antibacterial, and cytotoxic activities. Three secondary metabolites were isolated from a fermented culture of the sponge-associated fungal strain P. oxalicum CLC-MF05: oxaline (1), isorhodoptilometrin (2), and 5-hydroxy-7-(2'-hydroxypropyl)-2-methyl-chromone (3). Their chemical structures were identified by 1D and 2D NMR and high-resolution mass spectroscopic analyses and compared with previously reported data. All three compounds inhibited NO and PGE2 overproduction and iNOS and COX-2 overexpression in both LPS-stimulated BV2 and rat primary microglia. These metabolites also repressed mRNA expression of TNF-α, IL-1β, IL-6, and IL-12. Further, mechanistic studies revealed that the inhibitory actions of compounds 1-3 were regulated by the inactivation of the NF-κB and MAPK signaling pathways. Furthermore, inactivation of the TLR4/MyD88 pathway contributed to the anti-neuroinflammatory activity of these compounds. These results suggest that compounds 1-3 represent potential anti-inflammatory candidates for the treatment of neurodegenerative diseases; however, further investigation is needed.

Induction of Isochromanones by Co-Cultivation of the Marine Fungus Cosmospora sp. and the Phytopathogen Magnaporthe&nbsp;oryzae.

Microbial co-cultivation is a promising approach for the activation of biosynthetic gene clusters (BGCs) that remain transcriptionally silent under artificial culture conditions. As part of our project aiming at the discovery of marine-derived fungal agrochemicals, we previously used four phytopathogens as model competitors in the co-cultivation of 21 marine fungal strains. Based on comparative untargeted metabolomics analyses and anti-phytopathogenic activities of the co-cultures, we selected the co-culture of marine Cosmospora sp. with the phytopathogen Magnaporthe oryzae for in-depth chemical studies. UPLC-MS/MS-based molecular networking (MN) of the co-culture extract revealed an enhanced diversity of compounds in several molecular families, including isochromanones, specifically induced in the co-culture. Large scale co-cultivation of Cosmospora sp. and M. oryzae resulted in the isolation of five isochromanones from the whole co-culture extract, namely the known soudanones A, E, D (1-3) and their two new derivatives, soudanones H-I (4-5), the known isochromans, pseudoanguillosporins A and B (6, 7), naphtho-γ-pyrones, cephalochromin and ustilaginoidin G (8, 9), and ergosterol (10). Their structures were established by NMR, HR-ESIMS, FT-IR, electronic circular dichroism (ECD) spectroscopy, polarimetry ([α]D), and Mosher’s ester reaction. Bioactivity assays revealed antimicrobial activity of compounds 2 and 3 against the phytopathogens M. oryzae and Phytophthora infestans, while pseudoanguillosporin A (6) showed the broadest and strongest anti-phytopathogenic activity against Pseudomonas syringae, Xanthomonas campestris, M. oryzae and P. infestans. This is the first study assessing the anti-phytopathogenic activities of soudanones.

Antimicrobial and antifouling activities of the cellulase produced by marine fungal strain; Geotrichum candidum MN638741.1

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Enantioselective Total Synthesis of (−)‐Spiroxins A, C, and D

AbstractSpiroxins A, C, and D are metabolites that have been identified in the marine fungal strain LL‐37H248. Their unique polycyclic structures and intriguing biological activities make them attractive targets for the synthetic community. Based on a scalable enantioselective epoxidation of 5‐substituted naphthoquinone, an oxidation/spiroketalization cascade, ortho‐selective chlorination of the phenol unit, and oxime‐ester‐directed acetoxylation, an enantioselective total synthesis of (−)‐spiroxins A and C and the first total synthesis of (−)‐spiroxin D have been achieved.

Enantioselective Total Synthesis of (-)-Spiroxins A, C, and D.

Spiroxins A, C, and D are metabolites that have been identified in the marine fungal strain LL-37H248. Their unique polycyclic structures and intriguing biological activities make them attractive targets for the synthetic community. Based on a scalable enantioselective epoxidation of 5-substituted naphthoquinone, an oxidation/spiroketalization cascade, ortho-selective chlorination of the phenol unit, and oxime-ester-directed acetoxylation, an enantioselective total synthesis of (-)-spiroxins A and C and the first total synthesis of (-)-spiroxin D have been achieved.

Characterization and Cellulase Production Activity of different Aspergillus Sp. Isolated from “Puri, Odisha” Marine Fungal Strains

Cellulose undergoes hydrolysis utilizing chemicals to deliver glucose, which might be utilized for the production of ethanol, organic acids, and various chemicals. Cellulases are a collection of hydrolytic catalysts that can hydrolyze the most plentiful natural polymer for example cellulose into smaller sugar components including glucose subunits. Cellulase is overpriced and contributes simply half to the general expense of hydrolysis because of the low explicit activity. This enzyme has enormous potential in industries and its use in food, beverages, textile, laundry, paper, and mash industries, and so forth. Consequently, there has been a lot of examination focused on new microorganisms producing cellulose enzymes with higher specific activities and greater efficiency. Currently, work is pointed toward screening and disconnecting cellulolytic growths from the marine samples gathered from the Bay of Bengal, Puri coast, Odisha. All out 7 fungi were isolated from these dirt examples, out of which 2 fungi were portraying the extensive cellulase activity. The fungal isolate, for example, MWF-1 andMSF-6 isolated from water silt respectively were recognized to show the most extreme zone of hydrolysis of carboxy-methyl cellulose. The cellulase activity was assayed by Carboxymethylcellulose "CMCase" (endoglucanase) measure.

Marine endophytic fungi associated with Halopteris scoparia (Linnaeus) Sauvageau as producers of bioactive secondary metabolites with potential dermocosmetic application.

Marine fungi and, particularly, endophytic species have been recognised as one of the most prolific sources of structurally new and diverse bioactive secondary metabolites with multiple biotechnological applications. Despite the increasing number of bioprospecting studies, very few have already evaluated the cosmeceutical potential of marine fungal compounds. Thus, this study focused on a frequent seaweed in the Portuguese coast, Halopteris scoparia, to identify the endophytic marine fungi associated with this host, and assess their ability to biosynthesise secondary metabolites with antioxidative, enzymatic inhibitory (hyaluronidase, collagenase, elastase and tyrosinase), anti-inflammatory, photoprotective, and antimicrobial (Cutibacterium acnes, Staphylococcus epidermidis and Malassezia furfur) activities. The results revealed eight fungal taxa included in the Ascomycota, and in the most representative taxonomic classes in marine ecosystems (Eurotiomycetes, Sordariomycetes and Dothideomycetes). These fungi were reported for the first time in Portugal and in association with H. scoparia, as far as it is known. The screening analyses showed that most of these endophytic fungi were producers of compounds with relevant biological activities, though those biosynthesised by Penicillium sect. Exilicaulis and Aspergillus chevalieri proved to be the most promising ones for being further exploited by dermocosmetic industry. The chemical analysis of the crude extract from an isolate of A. chevalieri revealed the presence of two bioactive compounds, echinulin and neoechinulin A, which might explain the high antioxidant and UV photoprotective capacities exhibited by the extract. These noteworthy results emphasised the importance of screening the secondary metabolites produced by these marine endophytic fungal strains for other potential bioactivities, and the relevance of investing more efforts in understanding the ecology of halo/osmotolerant fungi.