Partial purification and characterization of a novel antifungal compound against Aspergillus spp. from Synechocystis sp. PCC 6803

Antimicrobial Peptides from Photosynthetic Marine Organisms with Potential Application in Aquaculture

Aquaculture production is at a record level and is estimated to increase in the coming years. However, this production can be negatively affected by infectious diseases produced by viruses, bacteria, and parasites, causing fish mortality and economic losses. Antimicrobial peptides (AMPs) are small peptides that may be promising candidates to replace antibiotics because they are the first line of defense in animals against a wide variety of pathogens and have no negative effects; they also show additional activities such as antioxidant or immunoregulatory functions, which makes them powerful alternatives for use in aquaculture. Moreover, AMPs are highly available in natural sources and have already been used in the livestock farming and food industries. Photosynthetic marine organisms can survive under all kinds of environmental conditions and under extremely competitive environments thanks to their flexible metabolism. For this reason, these organisms represent a powerful source of bioactive molecules as nutraceuticals and pharmaceuticals, including AMPs. Therefore, in this study we reviewed the present knowledge about AMPs from photosynthetic marine organism sources and analyzed whether they could be suitable for use in aquaculture.

Cyanobacteria, Lyngbya aestuarii and Aphanothece bullosa as antifungal and antileishmanial drug resources

OBJECTIVE

To investigate two cyanobacteria isolated from different origins i.e. Lyngbya aestuarii (L. aestuarii) from brackish water and Aphanothece bullosa (A. bullosa) from fresh water paddy fields for antifungal and antileishmanila activity taking Candida albicans and Leishmania donovain as targets.

METHODS

Biomass of L. aestuarii and A. bullosa were harvested after 40 and 60 d respectively and lyophilized twice in methanol (100%) and redissolved in methanol (5%) for bioassay. Antifungal bioassay was done by agar well diffusion method while antileishmanial, by counting cell numbers and flageller motility observation of promastigotes and amastigotes from L. donovani. Fluconazole and 5% methanol were used as control.

RESULTS

Both the cyanobacteria were found to be potent source of antifungal activity keeping fluconazole as positive control, however, methanolic crude extract (15 mg/mL) of A. bullosa was found more potent (larger inhibition zone) over that of methanolic crude extract of L. aestuarii. Similarly antileishmanial activity of crude extract (24.0 mg/mL) of A. bullosa was superior over that of methanolic crude extract of L. aestuarii (25.6 mg/mL).

CONCLUSIONS

Antifungal and antileishmanial drugs are still limited in the market. Screening of microbes possessing antifungal and antileishmanial activity drug is of prime importance. Cyanobacteria are little explored in this context because most of the drugs in human therapy are derived from microorganisms, mainly bacterial, fungal and actinomycetes. Thus in the present study two cyanobacterial strains from different origins showed potent source of antifungal and antileishmanial biomolecules.

SAR analysis and bioactive potentials of freshwater and terrestrial cyanobacterial compounds: a review

Freshwater and terrestrial cyanobacteria resemble the marine forms in producing divergent chemicals such as linear, cyclic and azole containing peptides, alkaloids, cyclophanes, terpenes, lactones, etc. These metabolites have wider biomedical potentials in targeting proteases, cancers, parasites, pathogens and other cyanobacteria and algae (allelopathy). Among the various families of non-marine cyanobacterial peptides reported, many of them are acting as serine protease inhibitors. While the micropeptin family has a preference for chymotrypsin inhibition rather than other serine proteases, the aeruginosin family targets trypsin and thrombin. In addition, cyanobacterial compounds such as scytonemide A, lyngbyazothrins C and D and cylindrocyclophanes were found to inhibit 20S proteosome. Apart from proteases, metabolites blocking the other targets of cancer pathways may exhibit cytotoxic effect. Colon and rectum, breast, lung and prostate are the worst affecting cancers in humans and are deduced to be inhibited by both peptidic and non-peptidic compounds. Moreover, the growth of infections causing parasites such as Plasmodium, Leishmania and Trypanosoma are well controlled by peptides: aerucyclamides A-D, tychonamides and alkaloids: nostocarboline and calothrixins. Likewise, varieties of cyanobacterial compounds tend to inhibit serious infectious disease causing bacterial, fungal and viral agents. Interestingly, portoamides, spiroidesin, nostocyclamide and kasumigamide are the allelopathic peptides determined to suppress the growth of toxic cyanobacteria and nuisance algae. Thus cyanobacterial compounds have a broad bioactive spectrum; the analysis of SAR studies will not only assist to find out the mode of action but also reveal bioactive key components. Thereby, developing the drugs bearing these bioactive skeletons to treat various illnesses is wide open.

WITHDRAWN: Cyanobacterial bioactive molecules - Biosynthesis and genetic regulation

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The cultivation of Anabaena variabilis in a bubble column operating under bubbly and slug flows

In a bubble column reactor with an inner diameter of 6cm and a height of 63cm for the culture of cyanobacteria two different shapes of bubbles can be generated, resulting in bubbly flow or slug flow. Growth of Anabaena variabilis under slug flow (1.9g/l/day) was 1.73 times higher than that under bubbly flow (1.1g/l/day) when the specific irradiation rate was maintained above 10μmol/s/g dry cell. Although a stepwise increase in superficial gas velocity enhanced the average cell growth rate under bubbly flow by 1.57 times, the average cell growth rate during the deceleration phase under bubbly flow (1.98g/l/day) was 0.61 times smaller than that under slug flow (3.22g/l/day). These results demonstrate that the bubble shape in the slug flow was advantageous in regards to the radial circulation of cells.