Biosurfactants are smart biomolecules which have wide spread application in medicines, processed foods, cosmetics as well as in bioremediation. In food industry, biosurfactants are used as emulsion stabilising agents, antiadhesives, and antimicrobial/antibiofilm agents. Nowadays biosurfactant demands in industries has increased tremendously and therefore new bacterial strains are being explored for large scale production of biosurfactants. In this study, an actinobacterial strain MSA31 was isolated from a marine sponge Fasciospongia cavernosa which showed high activity in biosurfactant screening assays such as drop collapsing, oil displacement, lipase and emulsification. Lipopeptide produced by MSA31 was found to be thermostable which was evident in differential scanning calorimetry analysis. The spectral data obtained in the Fourier transform infrared spectroscopy showed the presence of aliphatic groups combined with peptide moiety which is a characteristic feature of lipopeptides. The stability index of lipopeptide MSA31 revealed “halo-alkali and thermal tolerant biosurfactant” which can be used in the food industry. Microtiter plate assay showed 125µg/ml of lipopeptide was effective in reducing the biofilm formation activity of pathogenic multidrug resistant Staphylococcus aureus. The confocal laser scanning microscopic images provided further evidences that lipopeptide MSA31 was an effective antibiofilm agent. The antioxidant activity of lipopeptide MSA31 may be due to the presence of unsaturated fatty acid present in the molecule. The brine shrimp cytotoxicity assay showed lipopeptide MSA31 was non-toxic and can be used as food additives. Incorporation of lipopeptide MSA31 in muffin showed improved organoleptic qualities compared to positive and negative control. This study provides a valuable input for this lipopeptide to be used in food industry as an effective emulsifier, with good antioxidant activity and as a protective agent against S. aureus.

Sponge associated bacteria are a rich source of bioactive secondary metabolites. This study aims to isolate bacteria producing antimicrobial agents from a marine sponge, Callyspongia diffusa. A total of fifty-six bacteria were isolated and screened for antibacterial activity against multidrug resistant S. aureus. Based on the 16S rRNA sequence and phylogenetic analysis the antimicrobial producer strain MSI45 was identified as a novel Bacillus tequilensis. The culture conditions of strain MSI45 were optimized to enhance the yield of the antimicrobial compound. The antimicrobial compound was purified using a silica gel column chromatography and high performance liquid chromatography. On the basis of spectroscopic analysis such as FT-IR, NMR and GC-MS, the bioactive metabolite was identified as pyrrolo[1,2-a]pyrazine-1,4-dione,hexahydro. The extracted compound MSI45 showed a potent inhibitory effect on multidrug resistant S. aureus with an MIC of 15 ± 0.172 mg L⁻¹ and MBC of 20 ± 0.072 mg L⁻¹. The compound was non-hemolytic and showed high antioxidant activity. The antioxidant activity may increase the efficacy and safety of the molecule in drug development. Hence, this compound produced by Bacillus tequilensis MSI45 could have potent antimicrobial and antioxidant activity against S. aureus infection.

Microbiomes have highly important roles for ecosystem functioning and carry out key functions that support planetary health, including nutrient cycling, climate regulation, and water filtration. Microbiomes are also intimately associated with complex multicellular organisms such as humans, other animals, plants, and insects and perform crucial roles for the health of their hosts.

In the present study, a marine sponge-associated endosymbiotic bacterium Bacillus megaterium MSBN04 was evaluated for exopolysaccharide (EPS) production. The production process was optimized by central composite design (CCD). The productivity was increased up to 5.62 g L⁻¹ with sucrose as sole carbon source. The secreted EPS was characterized by NMR analysis, confirming the presence of monosaccharide units such as α-D-glucose and α-D-galactose, which further confirms that the secreted EPS is a heteropolysaccharide. The purified EPS showed considerable flocculating activity (45.41%) with 4 mg L⁻¹ of EPS. Using EPS as reducing and stabilizing agent, gold nanoparticles (AuNPs) were synthesized. The synthesized AuNPs (5–20 nm) were of spherical crystalline nature and capped with an EPS layer and were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The synthesis of AuNPs was dependent on the concentration of EPS. The synthesized AuNPs showed significant antibacterial activity against clinical pathogenic bacteria. Hence, EPS-mediated synthesis of AuNPs is an alternative approach to chemical synthesis and thus it is an environmentally benign, greener and economical approach.