The aim of present research in the first stage was to extract astaxanthin from Haematococcus pluvialis using acid-acetone method and then nanoencapsulation of the pigment using maltodextrin-sodium caseinate coating. In the next step, antioxidant and antibacterial activities of nanocapsules carrying astaxanthin and the free form of the pigment was evaluated. In order to evaluate antibacterial activity of the samples, Listeria monocytogenes, Staphylococcus aureus, Streptococcus iniae, Bacillus subtilis (Gram positive), Yersinia ruckeri, Escherichia coli and Enterobacter aerogenes (Gram negative) were used. The results showed that the antioxidant activity of nanocapsules carrying astaxanthin is significantly higher than the free form of pigment (p<0.05); In addition, this activity was improved by increasing the concentration of samples from 100 to 200 µg/ml (p<0.05). By astaxanthin nanoencapsulation, the diameter of non-growth zone of the studied bacteria increased (p<0.05), but minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the pigment and its carrier nanocapsules decreased (p<0.05). According to the results of zone of inhibition, Gram positive (except Listeria monocytogenes) and Gram negative bacteria were resistant up to concentrations of 60 and 80 µg/ml of samples, respectively. In the following, the MIC and MBC of the pigment (free and nanoencapsulated forms) for the seven bacteria ranged from 50 to 400 and 100 to 500 µg/ml, respectively. The results of evaluation the antioxidant and antibacterial activities of nanocapsules carrying astaxanthin during storage period (30 days at 4ºC) indicated stability and no significant change of these properties (p>0.05). According to the values of diameter of non-growth zone, MIC and MBC, Listeria monocytogenes was the most sensitive bacteria against astaxanthin and its carrier nanocapsules. Based on the findings, astaxanthin extracted from Haematococcus pluvialis has antioxidant and antibacterial activities, and these properties are improved by the pigment nanoencapsulation using maltodextrin-sodium caseinate coating.

Streptomyces are capable of producing secondary metabolites including antibiotics and the main environment of these microorganisms is soil. The purpose of this study was to isolate and evaluate Streptomyces producing antibacterial compounds from different east parts of Gilan province and optimizing antibacterial compounds produced by them. After isolation and purification of Streptomyces, its antibacterial activity against pathogenic microorganisms including Micrococcus luteus PTCC 1408, Bacillus cereus PTCC 1154, Staphylococcus aureus PTCC 1189, Pseudomonas aeruginosa PTCC 1310, Salmonella typhi PTCC 1609 and Proteus mirabilis PTCC 1776 was investigated. Streptomyces was identified based on morpholigaical, biochemical, physiological, 16SrRNA gene sequencing and phylogenetic analysis. Optimization of various factors in the content of production of antibacterial compounds was investigated. In this study, 16SrRNA gene sequencing revealed that the isolate belonged to Streptomyces genus and with the highest similarity (95. 70%) to Streptomyces malachitospinus indicating significant differences at species level and it can be introduced as a new species. This isolate showed significant activity against pathogenic microorganisms. The optimum culture medium, pH, temperature, carbon and nitrogen sources and incubation time for the maximum antibacterial compounds production were ISP2, 7, 28° C, glycerol, yeast extract and 7 days, respectively. The results show that the soils of the eastern regions of Gilan province are a rich source of antimicrobial compounds, which due to the resistance of the pathogenic microorganisms to antimicrobial drugs, is essential for the production of antimicrobial compounds from natural origin.