An updated inventory of marine opisthobranch(Mollusca,Gastropoda)from the territorial waters of the Republic of Mauritius

Island ecosystems support diverse aquatic invertebrate communities comprising endemic taxa.Documentation of existing species is important for conservation.In this study,a checklist of marine opisthobranch from the Republic of Mauritius is presented.A combination of benthic surveys(50 m×5 m in triplicates),rover diving techniques and photo documentation were used over two years(2018–2020)within 35 sheltered and unsheltered lagoons.Morphological and molecular analysis were used for identification.Species composition within sheltered and unsheltered areas in Mauritius was estimated using the Bray-Curtis similarity.The checklist featured 117 species belonging to 61 genera and 28families,of which 13 are new records.The findings increased the knowledge of opisthobranch diversity from the Mauritius by 15.4%.Among the listed species,the distribution range of Cyerce nigra,Actinocyclus papillatus,and Phyllidia picta extended from the Western Pacific to the South Western Indian Ocean.Molecular analysis of the undescribed Gymnodoris sp.showed it resembled Gymnodoris sp.from Hawaii and were different by a genetic distance value of 10.6%.The species richness and evenness were higher within the sheltered regions of Mauritius which harboured the food resource of opisthobranch.These areas as compared to unsheltered regions were heavily populated,suggesting the probable influence of wave actions on opisthobranch diversity and abundance.The order Nudibranchia was reported as most speciose,with 86 species.The Sacoglossa and Nudibranchia were observed only on macroalgae and sponges respectively.High abundance was also recorded on shipwrecks which are the most common form of artificial reefs.With the inclusion of observations from previous studies,201species belonging to 94 genera and 36 families are now known from the Mauritius.

Jatropha curcas L: Phytochemical, antimicrobial and larvicidal properties

Objective: To evaluate antimicrobial activities as well as the phytochemical and lavicidal 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 larvicidal effect was also studied in order to demonstrate the dual purpose of the plant.

In vitro antimicrobial and larvicidal properties of wild Ricinus communis L. in Mauritius

Objective: To explore the phytochemical and antimicrobial activities as well as the insecticidal properties of the different sections of Ricinus communis(castor) plant in Mauritius.Methods: Qualitative and quantitative methods were used for the determination of phytochemicals in the crude leaves, pericarp, seeds, bark and root extracts obtained by using polar and non-polar solvents. The disc diffusion and micro-dilution methods were used to evaluate the antimicrobial activities of the crude solvent extracts against 13 microorganisms. The insecticidal properties of the crude extracts on larvae of Bactrocera zonata(Diptera: Tephritidae), which caused important economic losses to local fruits were also investigated.Results: All the extracts from the different parts of the plant showed antimicrobial activity against most tested microorganisms. The polar solvents' extracts of the fully mature parts of the castor plant were active against the Pseudomonas aeruginosa(ATCC 27853),Escherichia coli(E. coli)(ATCC 25922), E. coli(0145:H28 Acc. No. CP006027.1) with inhibition zones ranging from 16 mm to 19 mm and against Bacillus cereus(ATCC11778)(B. cereus), Listeria innocua(ATCC 33090)(L. innocua). Lowest microbial inhibitory concentration was recorded for B. cereus, L. innocua, Staphylococcus aureus(ATCC 29213), E. coli(ATCC 25922) and Proteus mirabilis strain(NCTC 11938) with value of 3.2 mg/m L. The most active extract against both Gram-negative and Grampositive bacteria was extracted from the fully mature pericarps and it was the most active against E. coli(ATCC 25922), B. cereus, L. innocua and Staphylococcus aureus(ATCC 29213). In addition, the extracts obtained by using polar solvent and fully mature leaves demonstrated the strongest larvicidal activity against Bactrocera zonata(100%).Conclusions: Ricinus communis(castor) plant extracts possess larvicidal properties providing an effective eco-friendly control for fruit flies. The antimicrobial results justify the use of this plant in traditional medicine and the practice of supplementing decoctions/concoctions with conventional antibiotics.

Isolation of lactic acid bacteria from sugar cane juice and production of lactic acid from selected improved strains

Lactic acid bacteria (LAB) were isolated from fresh sugar cane juice. It was found that several isolates exhibited a clear zone and growth on deMan, Rogosa, Sharpe (MRS) agar supplemented with sodium azide, bromocresol purple and sucrose. However, only 17 isolates which formed large yellow areas were selected for further investigations. These isolates were further identified according to their morphological and biochemical characteristics. It was found that 10 of these isolates were homofermenters. One of these 10 isolates was selected for mutagenesis using chemical (Ethidium bromide) and physical (UV-B) mutagens followed by biochemical characterisation. A total of 112 mutants were isolated and 9 homofermentative isolates were further investigated for their ability to produce lactic acid. 1H-NMR spectroscopy confirmed that all mutant isolates produced lactic acid as the sole fermentation product.

An assessment of factors leading to the decline of Beclardia macrostachya (orchidaceae) population in Mauritius

Clearing of forest land for agriculture and urbanization following colonization have reduced the forest cover in Mauritius to 3% of total land cover. Today exotic species such as Psidium cattleianum (wild guava), Araucaria columnaris, and Ravenala madagascarensis dominate at Pigeon Wood, the only site in Mauritius where Beclardia can be found, leaving little space for very few indigenous tree species like Labourdonnaisia glauca, Apholoia theiformis and Foetida mauritiana. Beclardia macrostachya is an orchid endemic to Mauritius, Madagascar andReunion. Though it is abundant in the latter countries, it is one of the rarest orchids in Mauritius. An assessment of the factors associated with the stability of this orchid was carried out in forests of these three countries to understand the drastic decline of this orchid in Mauritius. Morphometric and fertility counts carried out at different forests revealed differences in fitness and fertility rates among forests of the same countries and between different countries. Stability of the different Beclardia populations was carried out based on counts of juveniles and adults. Higher fertility rates and most stable populations were observed in the forests of Reunion Island (Bebours) and Madagascar (Ambohitanteley), whereas very low fruit set were observed in Mauritius, unless manual pollination was carried out. Microscopic analysis revealed the presence of pelotons of endomycorrhiza during the early development of the seedlings, in vivo. Based on comparative studies among the different sites, pollinator limitation and absence of suitable hosts were the primary factors that led to the present decline in Mauritius. The high density of wild guava, Psidium cattleianum, which has slowly taken up most of the forest areas inMauritiushas affected the regenerating capacity of Beclardia macrostachya and the density of putative hosts of this orchid. GC-MS/MS analysis of nectar revealed α-D- glucopyranose to be the primary reward of the pollinators and benzyl alcohol, methoxybenzyl alcohol and methoxy methyl phenol to be components floral fragrance.

Anti-Microbial and Physico-Chemical Properties of Processed and Raw Honeys of Mauritius

Among the panoply of food products used in treatment of various ailments, honey has been used since prehistoric times as an effective antimicrobial therapy. Being first of its kind, honeys with specific botanical origin from Mauritius were examined. In this study, three commercially processed-enhanced v/s three unprocessed honeys were evaluated for possible antimicrobial activities against clinical bacterial (Enterococcus faecalis (ATCC 29212), Staphylococcus aureus (ATCC 29213), Escherichia coli (ATCC 25922), Pseudomonas aeroguinosa (ATCC 27853)) and fungal (Aspergillus niger (ATCC 16404) and Candida albicans (ATCC 10231)) isolates in vitro. Research findings showed that the respective physicochemical parameters of the samples ranged from;pH: 3.28 - 4.67, H2O: 17.63% - 24.87%, reducing sugar 42.95 - 60.31 g/100g, density 1.11 - 1.55 g/ml and viscosity: 1.85 - 26.24 Pa·s at 20°C. Physicochemical parameters of different honeys were observed to vary significantly with respect to their floral origin (P P < 0.05). The honey samples used in this study can be considered as valuable food products from their antimicrobial properties’ point of view and can have clinical potential.