Structural diversity and biological properties of secondary metabolites from sea hare (Aplysia dacdtylomela) and Alcyonacean soft corals

North Borneo, located in the Coral Triangle Region (CTR), the world's marine mega biodiversity, has an extremely rich source of marine life. The marine ecosystem is a fusion of complex interaction between the marine environment and marine organisms leading to predatory, competition for space or habitat, protection from disease or infection and directly imposing the pressure to survive among slowmoving, sessile soft bodied marine invertebrates. Thus, marine invertebrates biosynthesize secondary metabolites as a means ,of self defence. Recent development in drug discovery has revealed the potential of marine secondary metabolites as lead pharmaceutical drugs. This research focuses on two invertebrates; the sea hare Aplysia dactylomela Rang and Alcyonacean soft corals (Lobophytum pauciflorum, Sinularia flexibilis and Scleronephthea corymbosa) to investigate the structural diversity of secondary metabolites and its biological potentials. Populations of A. dactylomela from Dinawan Island yielded 10 compounds, Sulug Island yielded 9 compounds and Mantanani Island yielded 12 compounds, comprising of five new compounds with two new chemical skeletons. Compounds were mostly halogenated and comprised of acetogenins, charmigrane, cuparane, syndrean and bromoindoles. Three Alcyonacean soft coral species were analysed to contain 22 secondary metabolites; Lobophytum pauciflorum yielded 6 compounds, Scleronephthya corymbosa yielded 6 compounds and Sinularia flexibilis yielded 10 compounds comprising of furanocembranoids, pregnane type strerols and cembrane diterpenes. Secondary metabolites from the soft corals yielded five new compounds. Structure eluddation of compounds was determined via 10-NMR (proton and carbon), 2D-NMR (HSQC, COSY, HMBC and NOESY), HRMS and FTlR measurements. Sesquiterpenes (+)-elatol (16) and 2,3,5,6-tetrabromoindole (22) inhibited the growth of Escherichia coli (HP0408) and Vibrio cholera (HP0908) at MIC 5 µg/mL and 10 µg/mL. The syndrean 12-acetoxypalisadin B (0.02 %)(13) and pregnane sterol P3N-4 (0.01 %) (32) displayed cytotoxicity towards HL60 (13 µg/mL) and B16FI0 (17 µg/mL) cancer cell line respectively while the furanocembranoid SCl-8 (0.01 %) (28) best suppressed inflammation in LPS induced RAW 264.7 cell and zebra fish embryo at 10 µg/ml concentration. As such, the adaptation of marine invertebrate in the marine environment caters to great potential as an important source of lead pharmaceutical metabolites

Impact of Land-use Change on Vertical Soil Bacterial Communities in Sabah

Decline in forest productivity due to forest conversion is defining the Bornean landscape. Responses of bacterial communities due to land-use changes are vital and could define our understanding of ecosystem functions. This study reports the changes in bacterial community structure in organic soil (0–5 cm; O-Horizon) and organic-mineral soil (5– 15 cm; A-Horizon) across Maliau Basin Conservation Area old growth forest (MBOG), Fragment E logged forest (FELF) located in Kalabakan Forest Reserve to Benta Wawasan oil palm plantation (BWOP) using two-step PCR amplicon analysis of bacteria DNA on Illumina Miseq next generation sequencing. A total of 30 soil samples yielded 893,752-OTU reads at ≥97% similarity from 5,446,512 good quality sequences. Soil from BWOP plantation showed highest unshared OTUs for organic (49.2%) and organic-mineral (50.9%) soil. MBOG soil showed a drop in unshared OTUs between organic (48.6%) and organic-mineral (33.9%). At phylum level, Proteobacteria dominated MBOG but shifted to Actinobacteria in logged and plantation soil. Present findings also indicated that only FELF exhibited change in bacterial communities along the soil depth, moving from the organic to the organic-mineral layer. Both layers of BWOP plantation soils deviated from other forests’soil in β-diversity analysis. To our knowledge, this is the first report on transitions of bacterial community structures with different soil horizons in the tropical rainforest including Borneo, Sabah. Borneo tropical soils form a large reservoir for soil bacteria and future exploration is needed for fully understanding the diversity structure and their bacterial functional properties

Antimicrobial Potential of Aqueous Extract of Giant Sword Fern and Ultra-High-Performance Liquid Chromatography–High-Resolution Mass Spectrometry Analysis

Vibriosis and parasitic leech infestations cause the death of various farmed fish, such as groupers, hybrid groupers, sea bass, etc., in Malaysia and other Southeast Asian countries. In the absence of natural control agents, aquaculture operators rely on toxic chemicals to control Vibrio infections and parasitic leeches, which can have a negative impact on the environment and health. In the present study, we investigated the antivibrio and antiparasitic activities of the aqueous extract of giant sword fern (GSF) (Nephrolepis biserrata, Nephrolepidaceae, locally known as “Paku Pedang”) against four Vibrio spp. and the parasitic leech Zeylanicobdella arugamensis, as well as its metabolic composition using the ultra-high-performance liquid chromatography–high-resolution mass spectrometry system (UHPLC-HRMS). The data show that the aqueous extract of GSF at a concentration of 100 mg/mL exhibits potent bactericidal activity against V. parahaemolyticus with a zone of inhibition of 19.5 mm. In addition, the extract showed dose-dependent activity against leeches, resulting in the complete killing of the parasitic leeches within a short period of 11–43 min when tested at concentrations ranging from 100 to 25 mg/mL. The UHPLC-HRMS analysis detected 118 metabolites in the aqueous extract of GSF. Flavonoids were the primary metabolites, followed by phenolic, aromatic, fatty acyl, terpenoid, vitamin and steroidal compounds. Notably, several of these metabolites possess antibacterial and antiparasitic properties, including cinnamaldehyde, cinnamic acid, apigenin, quercetin, cynaroside, luteolin, naringenin, wogonin, 6-gingerol, nicotinamide, abscisic acid, daidzein, salvianolic acid B, etc. Overall, our study shows the significant antibacterial and antiparasitic potential of the GSF aqueous extract, which demonstrates the presence of valuable secondary metabolites. Consequently, the aqueous extract is a promising natural alternative for the effective control of Vibrio infections and the treatment of parasitic leeches in aquaculture systems

Halogenated Metabolites from the Diet of Aplysia dactylomela Rang

Invertebrates are an important source of structurally-diverse and biologically-active halogenated metabolites. The sea hare Aplysia dactylomela Rang has long been known to possess halogenated metabolites of dietary origin that are used as a self-defense mechanism. The compounds from Aplysia dactylomela Rang are comprised mainly of terpenoids and small percentages of C-15 acetogenins, indoles, macrolides, sterols and alkaloids with potent cytotoxic, anti-microbial and anti-inflammatory properties. For decades the metabolites discovered have been investigated for their medical and pharmaceutical applications, so much so that the ecological role of the metabolites has been overlooked. The interaction between Aplysia dactylomela Rang and its diet that is comprised of seaweed can provide information into the distribution and diversity of the seaweed, the application of bioaccumulated secondary metabolites as part of its defense mechanism and the potential roles of these metabolites for adaptation in the marine environment. This paper compiles the diversity of halogenated secondary metabolites documented from Aplysia dactylomela Rang

Food Waste Composting and Microbial Community Structure Profiling

Over the last decade, food waste has been one of the major issues globally as it brings a negative impact on the environment and health. Rotting discharges methane, causing greenhouse effect and adverse health effects due to pathogenic microorganisms or toxic leachates that reach agricultural land and water system. As a solution, composting is implemented to manage and reduce food waste in line with global sustainable development goals (SDGs). This review compiles input on the types of organic composting, its characteristics, physico-chemical properties involved, role of microbes and tools available in determining the microbial community structure. Composting types: vermi-composting, windrow composting, aerated static pile composting and in-vessel composting are discussed. The diversity of microorganisms in each of the three stages in composting is highlighted and the techniques used to determine the microbial community structure during composting such as biochemical identification, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE), terminal restriction fragment length polymorphism (T-RFLP) and single strand-conformation polymorphism (SSCP), microarray analysis and next-generation sequencing (NGS) are discussed. Overall, a good compost, not only reduces waste issues, but also contributes substantially to the economic and social sectors of a nation

Biological properties and chemical diversity of Sinularia Flexibilis, an Alcyonacean Soft Coral

Soft corals of the genus Sinularia (order Alcyonacea) are one of the most widespread sessile organisms in the Indo-Pacific waters. Unlike the hard corals, the major portion of soft coral is made up of inorganic skeletons consisting of calcareous spicules surrounded by a thin layer of tissue. This layer of tissue, made up of fleshy colonies with organic matter, is responsible in diversity of secondary metabolites. In order to survive the outburst of algal bloom, dynamic of microbial growth and predation of marine organisms, these soft corals synthesize unique chemicals as part of defense mechanism that makes them unpalatable to most marine life. As such, members of the genus Sinularia exhibits a diversity of secondary metabolites ranging from sesquiterpenes, diterpenes, polyhydroxylated steroids, and polyamine compounds. These metabolites had been shown to possess various biological activities such as antimicrobial, anti-inflammatory and cytotoxicity. This present paper reviews the chemistry and highlights the potential biological activities of metabolites from Sinularia flexibilis and provides a perspective for future research

A Systematic Review of the Physicochemical and Microbial Diversity of Well-Preserved, Restored, and Disturbed Mangrove Forests: What Is Known and What Is the Way Forward?

Mangrove forests are salt-tolerant intertidal vegetation in tropical and subtropical areas. Mangrove ecosystems provide commercial products, valuable fisheries, and aquaculture resources, protect and stabilize coastlines, and are important carbon sinks. However, they are threatened globally by human activities such as deforestation, pollution, and development causing fragmentation between the well-preserved, restored, and disturbed mangrove forests. Despite this, mangroves can adapt and strive well and are notable well associated with microbial diversity. Here, we investigate the diversity of microbes in different environmental settings using preferred reporting items for systematic and meta-analyses (PRISMA) analysis for publications from Scopus and the Web of Science databases. We report publications since 1987, and observed an exponential increase in publications beginning in the year 2000, which may be associated with the development of molecular and sequencing technologies. Differences in bacterial diversity was observed across the well-preserved, restored, and disturbed mangrove environments. Disturbed mangrove forests had a higher diversity (70 unique taxon orders reported) compared to well-preserved (33 unique taxon orders reported) and restored forests (38 unique taxon orders reported). Based on our analysis, we found that the microbial community plays an important role in the survival and adaptability of mangroves under varying environmental conditions. Thus, there is a need and a lot of potential for research in the area of mangrove microbiology with reference to ecology, biogeochemistry, and geomorphology