Valliappan Karuppiah

Functional gene-based discovery of phenazines from the actinobacteria associated with marine sponges in the South China Sea

Phenazines represent a large group of nitrogen-containing heterocyclic compounds produced by the diverse group of bacteria including actinobacteria. In this study, a total of 197 actinobacterial strains were isolated from seven different marine sponge species in the South China Sea using five different culture media. Eighty-seven morphologically different actinobacterial strains were selected and grouped into 13 genera, including Actinoalloteichus, Kocuria, Micrococcus, Micromonospora, Mycobacterium, Nocardiopsis, Prauserella, Rhodococcus, Saccharopolyspora, Salinispora, Serinicoccus, and Streptomyces by the phylogenetic analysis of 16S rRNA gene. Based on the screening of phzE genes, ten strains, including five Streptomyces, two Nocardiopsis, one Salinispora, one Micrococcus, and one Serinicoccus were found to be potential for phenazine production. The level of phzE gene expression was highly expressed in Nocardiopsis sp. 13-33-15, 13-12-13, and Serinicoccus sp. 13-12-4 on the fifth day of fermentation. Finally, 1,6-dihydroxy phenazine (1) from Nocardiopsis sp. 13-33-15 and 13-12-13, and 1,6-dimethoxy phenazine (2) from Nocardiopsis sp. 13-33-15 were isolated and identified successfully based on ESI-MS and NMR analysis. The compounds 1 and 2 showed antibacterial activity against Bacillus mycoides SJ14, Staphylococcus aureus SJ51, Escherichia coli SJ42, and Micrococcus luteus SJ47. This study suggests that the integrated approach of gene screening and chemical analysis is an effective strategy to find the target compounds and lays the basis for the production of phenazine from the sponge-associated actinobacteria.

Statistical optimization and anticancer activity of a red pigment isolated from Streptomyces sp. PM4

OBJECTIVE To enhance the pigment production by Streptomyces sp. PM4 for evaluating its anticancer activity. METHODS Response surface methodology was employed to enhance the production of red pigment from Streptomyces sp. PM4. Optimized pigment was purified and evaluated for the anticancer activity against HT1080, Hep2, HeLa and MCF7 cell lines by MTT assay. RESULTS Based on the response surface methodology, it could be concluded that maltose (4.06 g), peptone (7.34 g), yeast extract (4.34 g) and tyrosine (2.89 g) were required for the maximum production of pigment (1.68 g/L) by the Streptomyces sp. PM4. Optimization of the medium with the above tested features increased the pigment yield by 4.6 fold. Pigment showed the potential anticancer activity against HT1080, HEp-2, HeLa and MCF-7 cell lines with the IC50 value of 18.5, 15.3, 9.6 and 8.5 respectively. CONCLUSIONS The study revealed that the maximum amount of pigment could be produced to treat cancer.

Modification of artificial sea water for the mass production of (+)-terrein by Aspergillus terreus strain PF26 derived from marine sponge Phakellia fusca.

(+)‐Terrein shows multiple bioactivities, however, its mass production is a big challenge. Aspergillus terreus strain PF26 derived from South China Sea sponge Phakellia fusca has been cultured to produce (+)‐terrein successfully, but artificial sea water (ASW) of high salinity used in the fermentation medium may cause the corrosion risk of metal bioreactor, which limits the fermentation on a large scale. In this study, we modified the components of ASW by removing NaCl and CaCl2 from the original formula, which reduced about 80% salinity of ASW. As a result, 7·56 g l−1 (+)‐terrein production was achieved in shake flask, which was 78·72% higher than using the original ASW, and the cultivation time was decreased from 24 to 15 days. Then, the modified ASW was used for the fermentation of A. terreus strain PF26 in a 500 l stirred bioreactor, consequently 2·5 g l−1 of (+)‐terrein production was achieved.

Chapter 13 – Natural Products of Actinobacteria Derived from Marine Organisms

Abstract Actinobacteria are ubiquitous in the marine environment, which play a significant ecological role and generate natural products with pharmaceutical applications. The actinobacteria associated with marine organisms were probably involved with the host defense mechanism to evade pathogens. To date, 150 natural products within the structural classes of polyketides, isoprenoids, phenazines, peptides, indolocarbazoles, sterols, etc. have been isolated from the actinobacteria associated with sponges, corals, molluscs, ascidians, seaweeds, and mangroves. Among them, 9 novel and 62 new compounds have been reported. These compounds exhibit the bioactivities such as anticancer, antimicrobial, antiparasitic, neurological, antioxidant, and anti-HIV. This chapter is an effort to summarize the research on natural products of actinobacteria derived from marine organisms and to represent their perspective on drug discovery.

Marine Sponge Metagenomics

The sponge is one of the oldest multicellular invertebrates in the world. Because of its special pore canal structure and characteristics of filter feeding, a large amount of microorganisms adhere to it. After hundreds of thousands of years’ evolution, they form a kind of symbiosis relationship. A rather large amount of research shows the great diversity of microbes related to sponges using 16S rRNA (ribosomal ribonucleic acid) or 18S rRNA gene-based methods. Just in recent decades, many bioactive compounds have been separated from sponges. However, more and more studies confirm that those bioactive compounds do not derive from the sponges themselves but rather their symbionts. Considering that most of the microbes in sponges are unculturable, the culture-dependent approach is greatly limited. Using metagenomics, it may be possible to produce enzymes of special characteristics and secondary metabolites with biotechnological application from the sponge derived uncultured microbes. What is more, metagenomics can also serve as a way to understand the community structure, as well as the metabolism and function of a complex microbial community. This chapter focuses on techniques and advances in marine bacterial metagenomics, using sponge metagenomics as an example. Several aspects will be considered: The background and problems of sponge research (Sect. 17.1), the principle of metagenomics and related techniques (Sect. 17.2), the application and latest progress in sponge metagenomics (Sect. 17.3), and future perspectives (Sect. 17.4).

Natural Products with Anticancer Activity from Marine Fungi

Cancer is one of the major diseases, which require the improved drugs with fewer side effects. Until now, several marine natural products have been accessed for the anticancer property and few of them are in clinical trials too. Marine fungi are taxonomically diverse, largely productive, biologically active, and chemically unique offering a great scope for discovery of new anticancer drugs. The natural products isolated from the marine fungi are possibly inhibiting the processes such as inflammation, cell differentiation and survival, and metastasis of various signal transduction pathways and their by reducing the risk of cancer. In this chapter, we have discussed about the anticancer, anti-inflammatory and cytotoxic activities of marine derived fungi.