Multigene phylogeny, bioactive properties, enzymatic and dye decolorization potential of selected marine fungi from brown algae and sponges of Mauritius.

Marine fungi represent an important proportion of the microbial diversity in the oceans. They are attractive candidates for biotechnological purposes and industrial applications. Despite an increasing interest in mycology, marine fungi associated with sponges and algae have been poorly studied in Mauritius. The objectives of this study were to: 1) use multigene phylogenetic analyses to identify isolated marine fungi; 2) determine the differences in the antimicrobial and antioxidant properties of the fungal extracts; and 3) assess their enzyme activities and dye decolorization potential. Five fungal isolates viz Aspergillus chevalieri, Aspergillus iizukae, Aspergillus ochraceus, Exserohilum rostratum and Biatriospora sp. were identified based on phylogenetic analyses. There was no significant difference in the antimicrobial properties of the liquid and solid media extracts unlike the antioxidant properties (p < 0.05). The solid media extract of Aspergillus chevalieri (F2-SF) had a minimum inhibitory concentration of 0.156 mg/ml against Staphylococcus aureus while Aspergillus ochraceus (F25-SF) had a minimum inhibitory concentration of 0.313 and 2.5 mg/ml against Enterococcus faecalis and Salmonella typhi. The solid media extract of Biatriospora sp. (F34-SF) had a minimum inhibitory concentration of 0.195 and 1.563 mg/ml against Bacillus cereus, Escherichia coli and Enterobacter cloacae. An IC50 of 78.92 ± 4.71 µg/ml in the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging assay, ferric reducing antioxidant power (FRAP) value of 11.17 ± 0.20 mM Fe2+/g dry weight extract (DWE) and total phenolic content 360.35 ± 10.31 mg GAE/g DWE was obtained with the solid media extract of Aspergillus chevalieri (F2-SF). Aspergillus ochraceus (F25-SF) and Biatriospora sp. (F34-SF) solid media extracts showed lower IC50 values in the DPPH assay and higher total phenolic content as compared to the liquid media extracts. Aspergillus chevalieri was a good producer of the enzymes DNAse and lipase and had maximum percentage dye decolorization of 79.40 ± 17.72% on Congo red. An enzymatic index ≥ 2 was found for the DNAse and lipase and the maximum percentage dye decolorization of 87.18 ± 3.80% was observed with Aspergillus ochraceus on Methylene blue. Regarding Biatriospora sp., it was a moderate producer of the three enzymes amylase, DNAse and protease and had a maximum dye decolorization potential of 56.29 ± 6.51% on Crystal violet. This study demonstrates that Mauritian marine fungi possess good bioactive properties, enzymatic and dye decolorization potentials, that can potentially be considered for use in pharmaceutical and industrial applications.

Marine Microbial Polysaccharides: An Untapped Resource for Biotechnological Applications.

As the largest habitat on Earth, the marine environment harbors various microorganisms of biotechnological potential. Indeed, microbial compounds, especially polysaccharides from marine species, have been attracting much attention for their applications within the medical, pharmaceutical, food, and other industries, with such interest largely stemming from the extensive structural and functional diversity displayed by these natural polymers. At the same time, the extreme conditions within the aquatic ecosystem (e.g., temperature, pH, salinity) may not only induce microorganisms to develop a unique metabolism but may also increase the likelihood of isolating novel polysaccharides with previously unreported characteristics. However, despite their potential, only a few microbial polysaccharides have actually reached the market, with even fewer being of marine origin. Through a synthesis of relevant literature, this review seeks to provide an overview of marine microbial polysaccharides, including their unique characteristics. In particular, their suitability for specific biotechnological applications and recent progress made will be highlighted before discussing the challenges that currently limit their study as well as their potential for wider applications. It is expected that this review will help to guide future research in the field of microbial polysaccharides, especially those of marine origin.

Metabarcoding assessment of fungal diversity in brown algae and sponges of Mauritius.

Marine fungi are largely associated with second most inhabitants of the marine ecosystem such as sponges and algae. They are important colonizers and play vital ecological roles, such as nutrient cycling, organic matter decomposition, and symbiosis with other organisms. High throughput sequencing methods have been used successfully to reveal unknown fungal communities associated with a number of hosts particularly in the marine environment. However, the diversity of marine fungi associated with sponges and brown algae in Mauritius remains largely unknown. Traditional methods based on culturing do not provide reliable estimate of fungal diversity as only those that are able to grow under laboratory conditions are dominant; in addition, a large proportion of fungi, cultured in vitro remain most of the time unidentifiable, given that there are no sporulating structures to be examined morphologically. To overcome these limitations, we employed Illumina sequencing to unravel fungi species present in the sponges, Iotrochota sp. and Biemna sp. and the brown algae Turbinaria conoides, Sargassum pfeifferae, and Sargassum obovatum, collected from the north of Mauritius. Diversity analyses revealed that Biemna sp. had the highest diversity from the sampled sponges with fungi from 24 orders being recovered while from brown algae; Turbinaria conoides had the highest diversity with recovery of fungal taxa of the orders Botryosphaeriales, Chaetothyriales, Eurotiales, Hypocreales, and Mucorales with the latter four orders being common in both sampled algae and sponges. Beta diversity analyses revealed clustering only in the algae, Turbinaria conoides, and Sargassum pfeifferae and not in the co-occurring sponges, indicating that sampling location did not have much influence on fungal diversity. Our findings provide the first amplicon sequencing based insights of the fungal communities associated with macro-algae and sponges in Mauritius and supplements research on the fungal community existing in the oceans around the world.

Antimicrobial properties of marine fungi from sponges and brown algae of Mauritius.

Purpose of the study: Marine fungi of Mauritius have been poorly studied. There are numerous reports on the bioactive secondary metabolites that are produced by fungi around the world. Yet, research on the molecular characterisation and the pharmaceutical potential of marine fungi in Mauritius is rather scanty. Method: The samples, which consisted of three sponges Haliclona sp., Iotrochota sp. and Biemna sp. and two brown algae Turbinaria conoides and Sargassum portierianum, were collected in the North of Mauritius during winter. No sporulating structures were observed from the fungal cultures making morphological analysis impossible. The molecular characterisation of the selected isolates was carried out by the amplification of the ITS regions and phylogenetic analysis. The antimicrobial properties were then determined using the disc diffusion and the minimum inhibitory concentration (MIC) assay. Results: Genus level identification was made from molecular data and for some isolates, species-level identification was even possible. Twelve fungi that showed the best antimicrobial properties were identified as Peniophora sp., Aspergillus cristatus, Acremonium sp., Cordyceps memorabilis, Aspergillus ochraceus, Biscogniauxia sp., Aspergillus keratitidis, Exserohilum rostratum, Chromocleista sp., Nigrospora oryzae, Aspergillus flavipes and Mycosphaerella. The lowest MIC result of 0.0098 mg/mL was obtained with Chromocleista sp. mycelium extract against Staphylococcus aureus. The MIC of the mycelium extracts was lower than the broth extracts for most isolates indicating that the antimicrobial compounds are not secreted. Conclusion: Marine fungi from the Mauritian waters have immense potential in the search for natural products against antibiotic-resistant bacteria.

Author Correction: Hidden mycota of pine needles: Molecular signatures from PCR-DGGE and Ribosomal DNA phylogenetic characterization of novel phylotypes.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Pharmacological and polyphenolic profiles of Phyllanthus phillyreifolius var. commersonii Müll. Arg: An unexplored endemic species from Mauritius.

Phyllanthus phillyreifolius var. commersonii Müll. Arg is an endemic plant of Mauritius. To date, no study has been performed concerning its polyphenolic profile and pharmacological properties. In this study, a decoction (water), ethyl acetate and methanol extracts of the aerial parts of P. phillyreifolius, obtained from different extraction procedures (maceration and Soxhlet), were studied for antibacterial, antioxidant, anticancer, and enzyme inhibitory properties along with their polyphenolic profile. The ethyl acetate macerated extract showed high antibacterial activity against B. cereus (MIC = 0.293 mg/mL) and E. coli (MIC = 0.417 mg/mL) while S. epidermidis was most susceptible to the ethyl acetate-Soxhlet extract (MIC = 0.521 mg/mL). The methanol-Soxhlet extract displayed the most potent cupric and ferric reducing power, and metal chelating effect, while the macerated methanolic extract was the most effective DPPH and ABTS scavenger, and BChE inhibitor. Only the ethyl acetate-Soxhlet extract exhibited α-glucosidase inhibition. All extracts exhibited a strong anti-tyrosinase activity, which was further investigated by molecular docking and molecular dynamic. After 48 h exposure to the extracts for HeLa cell lines, the ethyl acetate-Soxhlet extract showed the highest inhibition (IC50 = 533.1 µg/mL) while the decoction extract was more cytotoxic to MDA-MB-231 cells (IC50 = 337.4 µg/mL). Treatment of cancer cell lines with all P. phillyreifolius extracts resulted in a time-dependent reduction of cell viability for HeLa and dose-and time-dependent reduction for MDA-MB-231. Gene expression ratio of Bcl-2 to Bax was higher for all Soxhlet-extracts. Total phenolics (TPC) and flavonoids (TFC) content were highest in the decoction and methanol-Soxhlet extract, respectively (122.43 mg GAE/g extract and 31.28 mg RE/g extract, respectively). The extracts were abundant in ellagitannins, although phenolic acids and flavonoids were also detected. Granatin B was detected for the first time in Phyllanthus species. Overall, the aerial parts of P. phillyreifolius exemplify a potent reservoir of bioactive phytochemicals for therapeutic applications.

Hidden mycota of pine needles: Molecular signatures from PCR-DGGE and Ribosomal DNA phylogenetic characterization of novel phylotypes.

Previous studies for enumerating fungal communities on pine needles relied entirely on phenotypic diversity (microscopy) or identification based on DNA sequence data from those taxa recovered via cultural studies. To bypass limitations of the culturing methods and provide a more realistic diversity estimate, we employed and assessed a PCR-DGGE based method coupled with rDNA phylogenetic sequence analyses to characterize fungal taxa associated with pine needles. Fresh (living) and decayed needles from three hosts of the Pinaceae (Keteleeria fortunei, Pinus elliottii and P. massoniana) were examined. Morphological studies reveal that the most abundant species associated with decayed needles were Cladosporium cladosporioides and an unidentified Trichoderma species followed by Gliocephalotrichum sp., Gliocladium sp., Lophodermium pinastri, Paecilomyces varioti, Phaeostalagmus cyclosporus and a Phoma sp, which are commonly occurring fungi. Community genomic data from freshly collected and decayed pine needles recovered 40 operational taxonomic units, which appear to be mostly undetected members of the natural fungal consortium. Sequence analyses revealed a number of phylotypes or "species" that were not recovered using traditional morphological and cultural approaches previously used. Phylogenetic data from partial 18S rDNA sequence data reveal that most phylotypes represent potential novel phylogenetic fungal lineages with affinities to the Dothideomycetes, Leotiomycetes, Lecanoromycetes and Sordariomycetes and were not identical to previously known endophytes or saprobes. Although the major ecological roles of these phylotypes in pine needles are still enigmatic, this study provides new insights in hidden fungal diversity that mycologists are possibly ignoring given the discrepancies associated with available methods. To what extent do previously recovered identified species (either as saprobes or endophytes) from morphological or culturing studies act as pioneer decomposers or constitute an integral part of endophytic community warrants further investigation.

Metatranscriptomics analysis of mangroves habitats around Mauritius.

Mangroves are unique but endangered coastal ecosystems that play a vital role in the tropical and subtropical environments. Mauritius has two species of mangroves, Bruguiera gymnorrhiza (L.) Lam. and Rhizophora mucronata Lam., growing along its coast. The mangrove rhizosphere harbours a diverse microbial community and the use of RNA-sequencing can reveal both the taxonomic composition and active biochemical functions of the complex microbial community. Metatranscriptomic study was carried out by comparing the microbial community of rhizosphere microbiomes sediments from the two mangroves species. The study also included a comparison between a natural and a man grown mangrove microbiome. Overall, samples showed predominance by Proteobacteria, Bacteroidetes and Firmicutes, with high abundance of sulphate reducers, nitrogen reducers and methanogens. Significant difference was, however, noted at both taxonomic and functional levels among the mangroves species. The data also indicate that the microbial core involved in methane, nitrogen, and sulphur metabolism consisted mainly of Burkholderiaceae, Planctomycetaceae, Rhodobacteraceae, and Desulfobacteraceae. Also, genes encoding enzymes involved in carbon cycling, the metabolism of nitrogen, methane and sulphur were dominant in the rhizosphere of the natural mangrove ecosystem. To our knowledge, this is a first metatranscriptomic study on the microbiome of mangroves in the Mauritius, and our results provide the first insights in the range of functions and microbial diversity of the local mangrove species.

Dietary intake and lifestyle behaviors of children in Mauritius.

The purpose of the study was to explore the dietary intake, fruit, vegetable and energy intake and lifestyle behaviors among Mauritian children. A validated questionnaire was used, assessing dietary intake, mean energy intake, mean body mass index (BMI), lifestyle behaviors as well as nutritional knowledge (NK) among males and females. 336 children aged 6-12 years (165 males and 171 females) from 8 public primary schools were recruited. Statistical analyses revealed that children consumed less nutritious foods such as fruits, vegetables and whole grains and more of refined and calorie-laden foods, with no significant differences across genders. Mean energy intake of children was 1522 ± 282.4 kcal per day while mean BMI was 17.5 ± 4.03 kg/m2. Majority of children had a low-to-moderate physical activity level (PAL), with males being more active than females on average (P = 0.021). 88.7% of children watched TV for more than an hour daily, with 84.8% of them reporting to be eating during the process. Females were more likely to be breakfast skippers (P = 0.003). Maximum frequency of snacking was twice daily (72.7%) while consumption of fast food was once or twice weekly (44.0%). Results indicate the need for intervention with aim of improving the dietary and life quality of children in Mauritius.

Early bacterial biofilm colonizers in the coastal waters of Mauritius

Background: The past years have witnessed a growing number of researches in biofilm forming communities due to their environmental and maritime industrial implications. To gain a better understanding of the early bacterial biofilm community, microfiber nets were used as artificial substrates and incubated for a period of 24 h in Mauritian coastal waters. Next-generation sequencing technologies were employed as a tool for identification of early bacterial communities. Different genes associated with quorum sensing and cell motility were further investigated. Results: Proteobacteria were identified as the predominant bacterial microorganisms in the biofilm within the 24 h incubation, of which members affiliated to Gammaproteobacteria, Alphaproteobacteria and Betaproteobacteria were among the most abundant classes. The biofilm community patterns were also driven by phyla such as Firmicutes, Bacteroidetes, Chloroflexi, Actinobacteria and Verrucomicrobia. The functional analysis based on KEGG classification indicated high activities in carbohydrate, lipid and amino acids metabolism. Different genes encoding for luxI, lasI, agrC, flhA, cheA and cheB showed the involvement of microbial members in quorum sensing and cell motility. Conclusion: This study provides both an insight on the early bacterial biofilm forming community and the genes involved in quorum sensing and bacterial cell motility.

Jatropha curcas L:Phytochemical, antimicrobial and larvicidal properties

Objective: To evaluate antimicrobial activities as well as the phytochemical and lav-icidal properties of different parts of Jatropha curcas L. (J. curcas) growing in Mauritius. Methods: Determination of the presence of phytochemicals in the crude plants extracts by test tube reactions. Disc diffusion method and microdilution method were used to detect the antimicrobial sensitivity and activity (minimal inhibitory concentration). The crude solvent extracts were also tested on the larvae of two insects, Bactrocera zonata and Bactrocera cucurbitae (Diptera, Tephritidae). Results: The antimicrobial activities were significantly dependent for the different crude plant extracts on the thirteen microorganisms tested. For the Gram-positive bacteria, the crude ethyl acetate extract was more efficient compared to the Gram-negative bacteria with both solvents being effective. The crude ethyl acetate extract of J. curcas bark and mature seed oil showed the highest efficacy. The highest mortality percentage was observed after 24 h for both Diptera flies with (66.67 ± 2.89)%of Bactrocera cucurbitae larvae killed by ethyl acetate extract of J. curcas bark. Conclusions: This paper compared the different J. curcas plant sections with respect to the effectiveness of the plant as a potential candidate for new pharmaceuticals. The lar-vicidal effect was also studied in order to demonstrate the dual purpose of the plant.

Repetitive element palindromic PCR (rep-PCR) as a genetic tool to study interspecific diversity in Euphorbiaceae family

Background The classification of diversity in germplasm collections is important for plant breeding. The repetitive element palindromic-polymerase chain reaction (rep-PCR) technique was used to investigate inter-specific diversity within 17 species from the Euphorbiaceae family using REP and BOX primers. Results The agglomerative cluster analysis was used to evaluate the scoring data. BOX and REP gave amplification with polymorphism of 98.84% and 100% respectively. REP marker demarcated between the subgenus peltatae. Both markers confirmed Jatropha tanjorensis as a natural hybrid between Jatropha gossypifolia and Jatropha curcas. Five random sequences from the rep-PCR gels were chosen, cloned and sequenced. The blast results demonstrated that the amplified products were from the mitochondrial genomes. Conclusion The rep-PCR molecular tool can be used to characterize diversity in plants as they are suitable for distinguishing eukaryotic genomes effectively.

Antimicrobial, phytochemical and larvicidal properties of Jatropha multifida Linn.

OBJECTIVE: To evaluate the phytochemical, antimicrobial and insecticidal properties of different extracts of Jatropha multifida (J. multifida) in Mauritius. METHODS: Qualitative and quantitative methods were used for the determination of the presence of phytochemicals in the crude solvent extracts of J. multifida. The antimicrobial sensitivity (disc diffusion method) and antibacterial activity (microdilution method) of 13 microorganisms were reported. The insecticidal properties of the crude solvent extracts were tested against the larvae of two insects, Bactrocera zonata and Bactrocera cucurbitae (Diptera: Tephritidae), which cause important economic losses to local fruits. RESULTS: Ethyl acetate was proved to be a good solvent for extraction. J. multifida showed very interesting activity against Bacillus algicola and Staphylococcus epidermis. The plant also showed good larvacidal activity against Bactrocera zonata. CONCLUSIONS: This paper reports the dual use of J. multifida, hence further studies can be made in term of application.

A comparison of polyphenolic content, antioxidant activity and insecticidal properties of Jatropha species and wild Ricinus communis L. found in Mauritius.

OBJECTIVE: To evaluate the phytochemical, antimicrobial and insecticidal properties of different Jatropha species and Ricinus communis (castor) (R. communis) growing in Mauritius. METHODS: Qualitative and quantitative methods were used for the determination of the presence of phytochemicals in the crude plants solvent extracts. The antimicrobial sensitivity (disc diffusion method) and Antibacterial activity (MIC-microdilution method) of 13 microorganisms were studied. The insecticidal properties of the crude solvent extracts against larvae of two insects, Bactrocera zonata and Bactrocera cucurbitae (Diptera, Tephritidae), which cause important economic losses to local fruits were also demonstrated. RESULTS: Ethyl acetate was proved to be a good solvent for extraction. Jatropha multifida showed very interesting activity against Bacillus algicola and Staphylococcus epidermis. Both R. communis and Jatropha multifida were proved to be very effective as biopesticide against different types of insect larvae. CONCLUSIONS: This study was able to demonstrate that Jatropha species as well as R. communis growing in Mauritius possess antimicrobial, phytochemical and insecticidal properties.

Biotechnology in Mauritius: current status and constraints

Agriculture today faces the challenge of sustainable productivity and improved food security on a shrinking area of land under cultivation. Until recently, biotechnology has been viewed as an expensive technology affordable only by rich industrial countries. However, it is now increasingly considered as an essential tool for developing countries to tackle the numerous problems of underdevelopment. Unfortunately, to date, Mauritius, like many other countries in Africa, lags far behind in development, use and commercialisation of biotechnology. This paper outlines the current status of biotechnology in Mauritius, some important constraints faced, as well as how policy makers are planning to make Mauritius ôassume the role of a service provider and know-how disseminator in the field of biotechnology by acting as a regional hub and a regional nurseryõ.