摘要
Marine actinobacteria are known to produce biomolecules with unique residues,including rare glycosidic linkages and complex branching patterns.These structural features confer a wide range of physical and chemical properties,making them highly valuable for biotechnological applications,especially in biomedicine and pharmacology.Among their notable functional roles,these biomolecules act as effective emulsifiers,stabilizing oil-water interfaces and offering potential for use in cosmetic formulations.Additionally,they exhibit cryoprotective properties,preventing ice formation and enhancing the viability of cells,tissues,and organs during cryopreservation an essential process for the long-term storage and transport of biological materials.This study has focused on isolating antifreeze proteins(AFPs)from marine actinobacteria sourced from polar environments,particularly Antarctica.Fourteen isolates were identified through conventional and molecular techniques.Optimal bacterial growth reached 2.092×10^(9) cells/ml at 120 h,significantly surpassing the control growth of 1.712×10^(7) cells/ml.Biofilm formation was observed to increase under optimal conditions,leading to the development of a well-structured biofilm matrix.Fridmanniella sp.SPF8(Strain from Polar Front 8)exhibited the highest biomolecule production,yielding 264.81 mg/ml,followed by Streptomyces sp.SPF6 with 104.53 mg/ml.Fridmanniella sp.SPF8 demonstrated strong functional properties,with 72%surfactant activity,91%hydrophobicity,92%inhibition of lipid peroxidation,and complete(100%)cryoprotective and antifreeze activities.Notably,this strain showed minimal membrane disturbance(10%)in human red blood cells,likely due to handling errors during experimentation.Further structural analysis of the antifreeze protein revealed that it consists of 32%α-helix,21%β-sheet,and 46%random coil structures.Domain analysis identified three domains:the SPFH-like_u1 domain(IPR033880),the SPFH domain YdjI(IPR033880),and the SPFH domain from the Band 7 family,all of which may contribute to the protein’s functional properties.In conclusion,the antifreeze proteins(AFP)from Fridmanniella sp.SPF8 exhibit potent emulsification,cryoprotective,and antioxidant activities,with minimal cytotoxicity,making them promising candidates for applications in biomedicine,cryopreservation,and industrial formulations.These findings highlight the potential of marine actinobacterial biomolecules for sustainable industrial and biomedical applications.
