Biotechnological applications of mangrove plants and their isolated compounds in medicine-a mechanistic overview.

Mangrove plants, also known as halophytes, are ecologically important plants that grow in various tropical and subtropical intertidal regions. Owing to the extreme abiotic and biotic stressful conditions they thrive in, these plants produce unique compounds with promising pharmacological propensities. Mangroves are inhabited by an astronomical number of fungal communities which produce a diverse array of extracellular degradative enzymes, namely: amylase, cellulase, xylanase, pectinase, cholesterol oxidase, etc. Such enzymes can be isolated from the mangrove fungi and harnessed for different biotechnological applications, for example, as replacements for chemical catalysts. Mangrove microbes attract considerable attention as they shelter the largest group of marine microorganisms that are resistant to extreme conditions and can produce novel biogenic substances. Vaccines developed from mangrove microbes may promise a safe future by developing effective immunization procedures with a minimum of economic burden. Interestingly, mangroves offer an exciting opportunity for synthesizing nanoparticles in a greener way as these plants are naturally rich in phytochemicals. Rhizophora mucronata Lam., Avicennia officinalis L. and Excoecaria agallocha L. are capable of synthesizing nanoparticles which have evolved recently as an alternative in various industries and are used for their biomedical application. Besides, the phytoconstituents isolated from mangrove plants, such as: gallic acid, galactose, lupeol, catechins, carotenoids, etc., were explored for various biological activities. These compounds are used in the pharmaceutical and nutraceutical industries to produce antimicrobial, antioxidant, anticancer, antidiabetic, and other therapeutic agents. The present review provides information on the biotechnological potentials of mangrove plants and their bioactive compounds as a new source of novel drugs, enzymes, nanoparticles and therapeutically important microbial pigments. Thus, this review forms a base of support and hasten the urgent research on biomedical applications of mangroves.

Jiella avicenniae sp. nov., a novel endophytic bacterium isolated from bark of Avicennia marina.

A Gram-stain-negative and short rod-shaped strain CBK1P-4T, isolated from surface-sterilized bark of Avicennia marina was investigated by a polyphasic taxonomic approach to resolve its taxonomic position. Strain CBK1P-4T grew at 10-30 °C (optimum, 25 °C), pH 5.0-9.0 (optimum, pH 5.5) and in the presence of 0-9% (w/v) NaCl (optimum, 1-2%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CBK1P-4T belonged to the genus Jiella and was most closely related to species of the genus Jiella (97.4-98.3%). The genome comparisons between strain CBK1P-4T and the closely related species indicated that average nucleotide identity and digital DNA-DNA hybridization values were below the recommended thresholds for assigning strains to the same species (95-96% and 70%, respectively). The cell wall peptidoglycan contained meso-diaminopimelic acid as diagnostic diamino acid. The principal fatty acids were C18:1ω7c and C19:0cycloω8c. The polar lipids were mainly comprised of phosphatidylcholine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, two unidentified aminolipids, one unidentified phospholipid and one unidentified glycolipid. The dominant respiratory quinone was ubiquinone-10. The DNA G + C content of strain CBK1P-4T was 66.7%. Based on the phenotypic features, phylogenetic analysis as well as genome analysis, we conclude that strain CBK1P-4T represents a novel Jiella species, for which the name Jiella avicenniae sp. nov. is proposed. The type strain is CBK1P-4T (= CGMCC 1.18742T = JCM 34330T).

Idiomarina mangrovi sp. nov., isolated from rhizosphere soil of a mangrove Avicennia marina forest.

A Gram-staining negative, aerobic, motile and rod-shaped bacterium, designated ZQ330T, was isolated from rhizosphere soil of a mangrove (Avicennia marina) forest of Zhangzhou, Fujian Province, China. The growth range of NaCl concentration was 0.5-10.0 % (w/v), with an optimum at 2.5-3.0 % (w/v), the temperature range for growth was 10-40 °C, with an optimum at 28-30 °C, the pH range for growth was pH 6.0-9.5, with an optimum at pH 7.5. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ZQ330T exhibited less than 97.0 % sequence similarity to all type strains with validly published names and revealed that strain ZQ330T formed a distinct lineage in the genus Idiomarina. The average nucleotide identity, and in silico DNA-DNA hybridization values between strain ZQ330T and the reference strains were 64.8-69.9 % and 27.5-28.4 %, respectively. Chemotaxonomic analysis indicated that the main respiratory quinone was Q-8, the predominant cellular fatty acids were iso-C15 : 0, iso-C17 : 0, summed feature 9 (C16 : 0 10-methyl and/or iso-C17 : 1ω9c), iso-C15 : 1F, C16 : 0, C18 : 0, summed feature 3 (C16 : 1ω8c and/or iso-C16 : 1 2-OH) and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unidentified glycolipid, an unidentified aminolipid, an unidentified phospholipid and two unidentified lipids. Based on the genotypic, phenotypic, chemotaxonomic and phylogenetic features, strain ZQ330T is considered to represent a novel species, for which the name Idiomarina mangrovi sp. nov. is proposed. The type strain is ZQ330T (=MCCC 1K03495T=KCTC 62455T).

Secondary metabolite as therapeutic agent from endophytic fungi Alternaria longipes strain VITN14G of mangrove plant Avicennia officinalis.

Endophytic fungi, especially from mangrove plants, are rich source of secondary metabolites, which plays a major role in various pharmacological actions preferably in cancer and bacterial infections. To perceive its role in antidiabetic activity we isolated and tested the metabolites derived from a novel strain Alternaria longipes strain VITN14G obtained from mangrove plant Avicennia officinalis. The crude extract was analyzed for antidiabetic activity and subjected to column chromatography. The isolated fractions were screened in vitro for α-glucosidase and α-amylase inhibitory activities. The cytotoxicity of the isolated fractions was studied on L929 cell lines. Following which, the screened fraction 2 was allowed for structure elucidation using gas chromatography-mass spectrometry, one-dimensional, two-dimensional nuclear magnetic resonance spectroscopy, ultraviolet, and Fourier-transform infrared analysis. The binding energies of the isolated fraction 2 with glycolytic enzymes were calculated by molecular docking studies using AutoDock Vina. The isolated fraction 2 identified as 2,4,6-triphenylaniline, showed no significant difference in α-amylase inhibition rates and a significant difference of 10% in α-glucosidase inhibition rates than that of the standard drug acarbose. Further, the cytotoxicity assay of the isolated fraction 2 resulted in a cell viability of 73.96%. Supportingly, in silico studies showed 2,4,6-triphenylaniline to produce a stronger binding affinity toward the glycolytic enzyme targets. The compound 2,4,6-triphenylaniline isolated from A. longipes strain VITN14G exhibited satisfactory antidiabetic activity for type 2 diabetes in vitro, which will further be confirmed by in vivo studies. Successful outcome of the study will result in a natural substitute for existing synthetic antidiabetic drugs.

Petroleum contamination and bioaugmentation in bacterial rhizosphere communities from Avicennia schaueriana

ABSTRACT Anthropogenic activity, such as accidental oil spills, are typical sources of urban mangrove pollution that may affect mangrove bacterial communities as well as their mobile genetic elements. To evaluate remediation strategies, we followed over the time the effects of a petroleum hydrocarbon degrading consortium inoculated on mangrove tree Avicennia schaueriana against artificial petroleum contamination in a phytoremediation greenhouse experiment. Interestingly, despite plant protection due to the inoculation, denaturing gradient gel electrophoresis of the bacterial 16S rRNA gene fragments amplified from the total community DNA indicated that the different treatments did not significantly affect the bacterial community composition. However, while the bacterial community was rather stable, pronounced shifts were observed in the abundance of bacteria carrying plasmids. A PCR-Southern blot hybridization analysis indicated an increase in the abundance of IncP-9 catabolic plasmids. Denaturing gradient gel electrophoresis of naphthalene dioxygenase (ndo) genes amplified from cDNA (RNA) indicated the dominance of a specific ndo gene in the inoculated petroleum amendment treatment. The petroleum hydrocarbon degrading consortium characterization indicated the prevalence of bacteria assigned to Pseudomonas spp., Comamonas spp. and Ochrobactrum spp. IncP-9 plasmids were detected for the first time in Comamonas sp. and Ochrobactrum spp., which is a novelty of this study.

TLC Screening Profile of Secondary Metabolites and Biological Activities of Salisapilia tartarea S1YP1 Isolated from Philippine Mangroves.

The Salisapilia species are estuarine oomycetes of the mangrove and saltmarsh ecosystem. To date, reports on the secondary metabolites and biological activities of these microorganisms are wanting. In this study, secondary metabolites in broth ethyl acetate extracts (BEAE) and mycelial ethyl acetate extracts (MEAE) of Salisapilia tartarea S1YP1 isolated from yellow senescent mangrove leaves were screened by Thin Layer Chromatography (TLC). Extracts were assayed for antioxidant, antibacterial, α- glucosidase inhibition, and cytotoxic activity. The TLC detected anthraquinones, anthrones, flavonoids, phenols, and triterpenes in both BEAE and MEAE. Coumarins were detected in BEAE but not in MEAE. Quantifying the total phenolics and total flavonoids content of the extracts in terms of gallic acid and quercetin equivalents, respectively shows that BEAE has higher total phenolic and flavonoid contents than MEAE. BEAE exhibited significant antioxidant activities through measurements of free radical scavenging activity against DPPH, hydroxyl, nitric oxide, and superoxide anion radicals as well as the ability to chelate Fe2+ metal ion. BEAE significantly inhibited in a dose-dependent manner α-glucosidase activity and selectively inhibited HepG2 cell proliferation. Antioxidant, α- glucosidase inhibitory, and cytotoxic activities have not been observed for MEAE. Both BEAE and MEAE do not have antibacterial activity.

Saccharopolyspora maritima sp. nov., an actinomycete isolated from mangrove sediment.

A novel Saccharopolyspora strain, designated 3SS5-12T, isolated from mangrove sediment collected from Ranong Province is described. The strain was characterized by pale yellow branching aerial mycelium which differentiated into flexuous chains of spores covered with tufts of short curved hairs. The whole-cell hydrolysates of the strain contained meso-diaminopimelic acid as the diagnostic diamino acid, with arabinose, galactose and ribose as the main sugars. A major menaquinone of this strain was MK-9(H4). Mycolic acids were absent. The DNA G+C content of the genomic DNA was 69.4 mol%. The predominant cellular fatty acids were iso-C16 : 0 and anteiso-C17 : 0. Polar lipids consisted of diphosphatidylglycerol, hydroxy-phosphatidylethanolamine, hydroxy-phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, unidentified phospholipids and unidentified lipids. Phylogenetic determination based on 16S rRNA gene sequences indicated that the organism was classified in the genus Saccharopolyspora and highly similar to Saccharopolyspora jiangxiensis W12T (98.8 % sequence similarity), Saccharopolyspora hirsutasubsp. kobensis JCM 9109T (98.8 %), Saccharopolyspora antimicrobica I05-00074T (98.2 %) and Saccharopolyspora indica VRC122T (98.1 %). Evidence from the chemotaxonomic, phenotypic and molecular systematic data indicated that strain 3SS5-12T should be classified as a representing novel species of the genus Saccharopolyspora, for which the name Saccharopolyspora maritima sp. nov. is proposed. The type strain is 3SS5-12T (=TBRC 7048T=NBRC 112863T).

Arenivirga flava gen. nov., sp. nov., a new member of the family Microbacteriaceae isolated from a mangrove tidal flat.

A novel Gram-stain-positive actinobacterium, designated HIs16-32T, was isolated from a sand sample collected from a mangrove tidal flat in Japan and its taxonomic position was investigated by a polyphasic approach. The cells of strain HIs16-32T were Gram-stain-positive, rod-shaped, non-motile and non-endospore-forming. Strain HIs16-32T contained glutamic acid, glycine and lysine in the peptidoglycan; however, alanine was absent. Galactose and mannose were detected as cell-wall sugars. The isoprenoid quinones were identified as MK-11, MK-12 and MK-10, and the major fatty acids as anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The DNA G+C content was determined to be 72.2 mol%. Phylogenetic analyses based on 16S rRNA gene sequence comparison revealed that strain HIs16-32T was related to members of the family Microbacteriaceae but did not form a reliable cluster with any known members of the family. The highest 16S rRNA gene sequence similarity values were obtained with species of the genera Herbiconiux(96.1-96.8 %), Plantibacter(96.5-96.7 %) and Schumannella (96.7 %). However, strain HIs16-32T was distinguishable from the phylogenetically related genera in terms of chemotaxonomic characteristics and phylogenetic relationship. Therefore, strain HIs16-32T is concluded to represent a novel genus and species of the family Microbacteriaceae, for which the name Arenivirga flava gen. nov., sp. nov. is proposed. The type strain of A. flava is HIs16-32T (=NBRC 112289T=TBRC 7038T).

Paracoccus mangrovi sp. nov., isolated from a mangrove.

A bacterial strain, designated gyp-1T, was isolated from a mangrove in Taiwan and characterized using the polyphasic taxonomic approach. Cells of gyp-1T were Gram-staining-negative, aerobic, poly-ß-hydroxybutyrate-accumulating, non-motile, coccoid or short-rod-shaped and formed cream-coloured colonies. Growth occurred at 15-37 °C (optimum, 25-30 °C), at pH 5.5-7.0 (optimum, pH 6.0) and with 0-4 % NaCl (optimum, 1-2 %). Phylogenetic analyses based on 16S rRNA gene sequences indicated that gyp-1T represented a member of the genus Paracoccus and showed the highest levels of sequence similarity with respect to Paracoccus lutimaris HDM-25T (97.8 %) and Paracoccus aminovorans DM-82T (97.7 %). The major fatty acids (>10 %) of gyp-1T were C18 : 1ω7c and C16 : 0. The polar lipid profile consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, diphosphatidylglycerol, an unidentified glycolipid and two unidentified phospholipids. The major isoprenoid quinone was Q-10. The DNA G+C content was 64.6 mol%. The DNA-DNA hybridization value for gyp-1T with P. lutimaris HDM-25T and P. aminovorans DM-82T was less than 50 %. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that gyp-1T should be classified as representing a novel species of the genus Paracoccus, for which the name Paracoccus mangrovi sp. nov. is presented. The type strain is gyp-1T (=BCRC 80920T=LMG 29172T=KCTC 42899T).

Nonomuraea purpurea sp. nov., an actinomycete isolated from mangrove sediment.

A polyphasic approach was used to verify the novel actinomycete, strain 1SM4-01T, isolated from mangrove sediment collected from Ranong Province, Thailand. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the organism was a member of the genus Nonomuraea and was most closely related to Nonomuraea syzygii GKU 164T (98.7 % sequence similarity), Nonomuraea rhizophila YIM 67092T (98.4 %), Nonomuraea solani NEAU-Z6T (98.4 %), Nonomuraea monospora PT708T (98.3 %) and Nonomuraea thailandensis KC-061T (98.2 %). The strain produced branching aerial mycelium which differentiated into straight chains of rough-surfaced spores borne at the end of a short sporophore. The whole-cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, with madurose, mannose and ribose as the main sugars. MK-9(H4) was a major menaquinone of this strain. The acyl type of peptidoglycan was N-acetyl. The predominant cellular fatty acids were C17 : 1ω8c and iso-C16 : 0. Phospholipids consisted of diphosphatidylglycerol, hydroxy-phosphatidylethanolamine, hydroxy-phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, aminophospholipids and unidentified lipids. The G+C content of the genomic DNA was 70.4 mol%. On the basis of phenotypic characteristics, DNA-DNA relatedness and phylogenetic distinctiveness, strain 1SM4-01T represents a novel species of the genus Nonomuraea, for which the name Nonomuraea purpurea sp. nov. is proposed. The type strain is 1SM4-01T (=BCC 60397T=NBRC 109647T).

Kocuria pelophila sp. nov., an actinobacterium isolated from the rhizosphere of a mangrove.

A novel spherical actinobacterium, designated RS-2-3T, was isolated from the rhizosphere of a mangrove growing on Rambut Island, Indonesia, and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that strain RS-2-3T was related to the members of the genus Kocuria. The highest 16S rRNA gene sequence similarity value was observed with Kocuria marina KMM 3905T (97.0 %). The peptidoglycan type of strain RS-2-3T was found to be A3α with an interpeptide bridge comprising l-Ala4-5. The predominant menaquinone was MK-7(H2) and the major fatty acids were anteiso-C15 : 0 and iso-C15 : 0. The DNA G+C content was 71.8 mol%. These characteristics were consistent with those of members of the genus Kocuria. Meanwhile, physiological and biochemical characteristics revealed that strain RS-2-3T differed from the species of the genus Kocuria with validly published names. Therefore, strain RS-2-3T represents a novel species of the genus Kocuria, for which the name Kocuria pelophila sp. nov. is proposed. The type strain is RS-2-3T (=NBRC 110990T=InaCC A704T).

Deciphering the salinity adaptation mechanism in Penicilliopsis clavariiformis AP, a rare salt tolerant fungus from mangrove.

Penicilliopsis clavariiformis AP, a rare salt tolerant fungus reported for the first time from India was identified through polyphasic taxonomy. Scanning electron microscopy showed that the fungus has unique features such as biverticillate penicilli bearing masses of oval to ellipsoidal conidia. The fungus has been characterized for salt tolerance and to understand the relevance of central carbon metabolism in salt stress adaptation. It showed optimal growth at 24 °C and able to tolerate up to 10% (w/v) NaCl. To understand the mechanism of adaptation to high salinity, activities of the key enzymes regulating glycolysis, pentose phosphate pathway, and tricarboxylic acid cycle were investigated under normal (0% NaCl) and saline stress environment (10% NaCl). The results revealed a re-routing of carbon metabolism away from glycolysis to the pentose phosphate pathway (PPP), served as a cellular stress-resistance mechanism in fungi under saline environment. The detection and significant expression of fungus genes (Hsp98, Hsp60, HTB, and RHO) under saline stress suggest that these halotolerance conferring genes from the fungus could have a role in fungus protection and adaptation under saline environment. Overall, the present findings indicate that the rearrangement of the metabolic fluxes distribution and stress related genes play an important role in cell survival and adaptation under saline environment.

Lasiodiplodins from mangrove endophytic fungus Lasiodiplodia sp. 318.

Four new lasiodiplodins (1-4), together with three known analogues, have been isolated from a mangrove endophytic fungus, Lasiodiplodia sp. 318#. Their structures were elucidated by spectroscopic techniques. Cytotoxic activities of compounds 1-7 were evaluated in vitro against human cancer lines THP1, MDA-MB-435, A549, HepG2 and HCT-116. Compound 4 exhibited moderate cytotoxic activities.

Proposal of nine novel species of the genus Lysinimicrobium and emended description of the genus Lysinimicrobium.

Thirteen novel Gram-stain-positive bacteria were isolated from various samples collected from mangrove forests in Japan, and their taxonomic positions were investigated by a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequence comparisons showed that the 13 isolates formed a single clade with Lysinimicrobium mangrovi HI08-69T, with a similarity range of 97.6-99.5 %. The peptidoglycan of the isolates was of the A4α type with an interpeptide bridge comprising Ser-Glu and an l-Ser residue at position 1 of the peptide subunit. The predominant menaquinone was demethylmenaquinone DMK-9(H4) and the major fatty acid was anteiso-C15 : 0. These chemotaxonomic characteristics corresponded to those of the genus Lysinimicrobium. On the basis of the phenotypic and phylogenetic data, along with average nucleotide identity values among the isolates, we concluded that the 13 isolates should be assigned to the following nine novel species of the genus Lysinimicrobium: Lysinimicrobium aestuarii sp. nov. (type strain HI12-104T = NBRC 109392T = DSM 28144T), Lysinimicrobium flavum sp. nov. (type strain HI12-45T = NBRC 109391T = DSM 28150T), Lysinimicrobium gelatinilyticum sp. nov. (type strain HI12-44T = NBRC 109390T = DSM 28149T), Lysinimicrobium iriomotense sp. nov. (type strain HI12-143T = NBRC 109399T = DSM 28146T), Lysinimicrobium luteum sp. nov. (type strain HI12-123T = NBRC 109395T = DSM 28147T), Lysinimicrobium pelophilum sp. nov. (type strain HI12-111T = NBRC 109393T = DSM 28148T), Lysinimicrobium rhizosphaerae sp. nov. (type strain HI12-135T = NBRC 109397T = DSM 28152T), Lysinimicrobium soli sp. nov. (type strain HI12-122T = NBRC 109394T = DSM 28151T) and Lysinimicrobium subtropicum sp. nov. (type strain HI12-128T = NBRC 109396T = DSM 28145T). In addition, an emended description of the genus Lysinimicrobium is proposed.

Jiangella mangrovi sp. nov., isolated from mangrove soil.

An aerobic, Gram-stain-positive actinomycete, designated strain 3SM4-07T, was characterized using a polyphasic taxonomic approach. The strain produced branching mycelium which fragmented into short or elongated rods. The whole-cell hydrolysates contained ll-2,6-diaminopimelic acid as the diagnostic diamino acid, with glucose and ribose as the main sugars. The predominant cellular fatty acids were anteiso-C15  :  0, iso-C15  :  0 and iso-C16  :  0.The predominant menaquinone was MK-9(H4). Phospholipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol and phosphatidylinositol mannoside. Mycolic acids were absent. The DNA G+C content was 72.3 mol%. Strain 3SM4-07T formed a phylogenetic line within the genus Jiangella and its 16S rRNA gene sequence was related most closely to Jiangella alkaliphila D8-87T (99.0% similarity), Jiangella muralis 15-Je-017T (98.8%), Jiangella alba YIM 61503T (98.6%) and Jiangella gansuensis YIM 002T (98.6%). However, mean DNA-DNA hybridization values revealed that strain 3SM4-07T differed from the closest species previously described in this genus. Data from phenotypic, chemotaxonomic and molecular analyses between strain 3SM4-07T and recognized species of the genus Jiangella indicate that strain 3SM4-07T is a representative of a novel species of the genus Jiangella, for which the name Jiangella mangrovi sp. nov. is proposed. The type strain is 3SM4-07T ( = BCC 60398T = NBRC 109648T).

Sinomonas humi sp. nov., an amylolytic actinobacterium isolated from mangrove forest soil.

Strain MUSC 117(T) was isolated from mangrove soil of the Tanjung Lumpur forest in Pahang, Malaysia. This bacterium was yellowish-white pigmented, Gram-staining-positive, rod-coccus shaped and non-motile. On the basis of 16S rRNA gene sequence, strain MUSC 117(T) exhibited highest sequence similarity to Sinomonas atrocyanea DSM 20127(T) (98.0 %), Sinomonas albida LC13(T) (97.9 %) and Sinomonas soli CW 59(T) (97.8 %), and lower (<97.6 %) sequence similarity to other species of the genus Sinomonas. DNA-DNA hybridization experiments revealed a low level of DNA-DNA relatedness (less than 27 %) between strain MUSC 117(T) and closely related species. Chemotaxonomically, the peptidoglycan type was A3α, containing the amino acids lysine, serine, glycine, alanine, glutamic acid and muramic acid. The whole-cell sugars detected were rhamnose, ribose, glucose, galactose and a smaller amount of mannose. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and five unidentified glycolipids. The major fatty acids (>10.0 %) of the cell membrane were anteiso-C15 : 0 (39.4 %), C18 : 1ω7c (17.7 %), anteiso-C17 : 0 (17.2 %) and iso-C16 : 0 (11.4 %). The predominant respiratory quinones detected were MK-9(H2) and MK-9. The DNA G+C content was 67.3 mol%. A comparison of BOX-PCR fingerprints indicated that strain MUSC 117(T) represented a unique DNA profile. Results based on a polyphasic approach showed that strain MUSC 117(T) represents a novel species of the genus Sinomonas, for which the name Sinomonas humi sp. nov. is proposed. The type strain of Sinomonas humi sp. nov. is MUSC 117(T) ( = DSM 29362(T) = MCCC 1K00410(T) = NBRC 110653(T)).

Serinibacter tropicus sp. nov., an actinobacterium isolated from the rhizosphere of a mangrove, and emended description of the genus Serinibacter.

A novel Gram-stain-positive actinobacterium, designated PS-14-7(T), was isolated from the rhizosphere of a mangrove on Pramuka Island, Indonesia, and its taxonomic position was investigated using a polyphasic approach. The peptidoglycan type of strain PS-14-7(T) was A4α and lysine was the diagnostic diamino acid of the peptidoglycan. The predominant menaquinone was MK-8(H4) and the major fatty acids were anteiso-C(15 : 0), C(16 : 0) and iso-C(16 : 0). The DNA G+C content was 72.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain PS-14-7(T) was closely related to Serinibacter salmoneus Kis4-28(T) (99.6%). However, DNA-DNA hybridization and phenotypic characteristics revealed that strain PS-14-7(T) differed from Serinibacter salmoneus . Therefore, strain PS-14-7(T) represents a novel species of the genus Serinibacter , for which the name Serinibacter tropicus sp. nov. is proposed. The type strain is PS-14-7(T) ( = NBRC 110108(T) = InaCC A 515(T)). An emended description of the genus Serinibacter is also proposed.

Brocazines A-F, Cytotoxic Bisthiodiketopiperazine Derivatives from Penicillium brocae MA-231, an Endophytic Fungus Derived from the Marine Mangrove Plant Avicennia marina.

Six new disulfide-bridged diketopiperazine derivatives, brocazines A-F (1-6), along with one known analogue (7), were isolated and identified from the cytotoxic extract of Penicillium brocae MA-231, a fungus obtained from the fresh tissue of the marine mangrove plant Avicennia marina. The structures of these compounds were established on the basis of detailed interpretation of NMR and mass spectroscopic data. X-ray crystallographic analysis confirmed the structure of 1 and established the structure and absolute configuration of 5, while the absolute configurations for compounds 1, 4, and 6 were deduced by comparison of the CD data with those of 5. Compounds 1, 2, 5, and 6 showed cytotoxic activities against several tumor cell lines.

Microbacterium mangrovi sp. nov., an amylolytic actinobacterium isolated from mangrove forest soil.

Strain MUSC 115(T) was isolated from mangrove soil of the Tanjung Lumpur river in the state of Pahang, Peninsular Malaysia. Cells of this strain stained Gram-positive and were non-spore-forming, short rods that formed yellowish-white colonies on different agar media. The taxonomy of strain MUSC 115(T) was studied by a polyphasic approach, and the organism showed a range of phylogenetic and chemotaxonomic properties consistent with those of the genus Microbacterium. The cell-wall peptidoglycan was of type B2ß, containing the amino acids ornithine, alanine, glycine, glutamic acid and homoserine. The muramic acid was of the N-glycolyl form. The predominant menaquinones detected were MK-12, MK-13 and MK-11. The polar lipids consisted of phosphatidylglycerol, phosphoglycolipid, diphosphatidylglycerol, two unidentified lipids, three unidentified phospholipids and four unidentified glycolipids. The major fatty acids of the cell membrane were anteiso-C15:0 and anteiso-C17:0. The whole-cell sugars detected were ribose, glucose, mannose and galactose. Based on the 16S rRNA gene sequence, strain MUSC 115(T) showed the highest sequence similarity to Microbacterium immunditiarum SK 18(T) (98.1%), M. ulmi XIL02(T) (97.8%) and M. arborescens DSM 20754(T) (97.5%) and lower sequence similarity to strains of other species of the genus Microbacterium. DNA-DNA hybridization experiments revealed a low level of DNA-DNA relatedness (less than 24%) between strain MUSC 115(T) and the type strains of closely related species. Furthermore, BOX-PCR fingerprint comparison also indicated that strain MUSC 115(T) represented a unique DNA profile. The DNA G+C content determined was 70.9 ± 0.7 mol%, which is lower than that of M. immunditiarum SK 18(T). Based on the combination of genotypic and phenotypic data, it is proposed that strain MUSC 115(T) represents a novel species of the genus Microbacterium, for which the name Microbacterium mangrovi sp. nov. is proposed. The type strain is MUSC 115(T) ( = MCCC 1K00251(T) = DSM 28240(T) = NBRC 110089(T)).

Natural products from mangrove actinomycetes.

Mangroves are woody plants located in tropical and subtropical intertidal coastal regions. The mangrove ecosystem is becoming a hot spot for natural product discovery and bioactivity survey. Diverse mangrove actinomycetes as promising and productive sources are worth being explored and uncovered. At the time of writing, we report 73 novel compounds and 49 known compounds isolated from mangrove actinomycetes including alkaloids, benzene derivatives, cyclopentenone derivatives, dilactones, macrolides, 2-pyranones and sesquiterpenes. Attractive structures such as salinosporamides, xiamycins and novel indolocarbazoles are highlighted. Many exciting compounds have been proven as potential new antibiotics, antitumor and antiviral agents, anti-fibrotic agents and antioxidants. Furthermore, some of their biosynthetic pathways have also been revealed. This review is an attempt to consolidate and summarize the past and the latest studies on mangrove actinomycetes natural product discovery and to draw attention to their immense potential as novel and bioactive compounds for marine drugs discovery.