Polyunsaturated fatty acid-producing marine thraustochytrids: A potential source for antimicrobials

Isolation and Optimization of Culture Conditions of Thraustochytrium kinnei for Biomass Production, Nanoparticle Synthesis, Antioxidant and Antimicrobial Activities

“…Thraustochytrids were isolated from decomposing mangrove leaves of Rhizophora annamalayana Kathir., collected from a mangrove forest in Pichavaram on the southeast coast of India, by the pour plate method on GPYAS culture medium containing Glucose (3 g•L −1 ), Peptone (1.25 g•L −1 ), Yeast extract (1.25 g•L −1 ), and Agar (12 g•L −1 ) in sterile natural seawater with the addition of antibacterial (streptomycin 100 µg•L −1 ) and antifungal (fluconazole 100 µg•L −1 ) agents to prevent contaminations, adjusted to a pH of 7.2 and incubated at 28 • C for 2-7 days [2,3]. The pure cultures were found after 3 repeated sub-cultures in 2-7 days, and culture stocks were maintained on agar slants.…”

“…1 filter paper and centrifuged at 5000 rpm for 10 min. Supernatant of the extract was collected and tested for antibacterial activity by the agar disc diffusion method [2] against 10 clinical bacterial strains: Proteus mirabilis (P. mirabilis), Staphylococcus aureus (S. aureus), Streptococcus pyogens (S. pyogens), Vibrio cholerae (V. cholerae), Vibrio parahaemolyticus (V. parahaemolyticus), Escherichia coli (E. coli), Klebsiella pneumonia (K. pneumonia), Klebsiella oxytoca (K. oxytoca), Salmonella typhi (S. typhi), and Salmonella paratyphi (S. paratyphi), obtained from Raja Muthiah Medical College, Annamalai University, India. The 24-hour-old bacterial culture cell suspension (100 µL) of each of the strains was poured onto the nutrient agar plates and spread using a glass spreader aseptically.…”

“…A sterile disc (6 mm) was soaked with 100 µL of silver and gold nanoparticle extract of thraustochytrid strain TSKK1 separately. Lyophilized thraustochytrid strain was extracted with petroleum ether and tested for antibacterial activity [2] separately for the comparison of synthesized nanoparticles and normal solvent extract. Ampicillin antibiotic was used as a positive control and distilled water as a negative control.…”

“…They are unicellular and heterotrophic protists, abundantly present in decomposing mangrove litter [1]. The thraustochytrids are known to produce polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are promising for pharmaceutical and industrial applications, especially in aquaculture [2][3][4]. They contain 10-50% lipids, of which 30-70% is DHA [5].…”

“…Thraustochytrids are explored for the production of a wide range of bioactive compounds as a supplement for the production of animal feed [21], antimicrobials [2], antioxidants [3], biodiesel [22], enzymes [23], carotenoids [24], squalene [25], exopolysaccharides [26], vaccines [27], and cancer drugs [28]. There are no reports of thrautochytrids producing toxic chemicals [29].…”