The role of commercial probiotic (Bacillus subtilis and Bacillus coagulans) and halophilic (Bacillus sp.) bacteria isolated from Urmia Lake on water quality improvement, biofloc production and composition using different carbon sources

In this study, the role of probiotic and halophilic bacteria were studied in biofloc system using different carbon sources including corn starch (treatments 1 and 4), beetroot molasses (treatments 2 and 5), rice-bran (treatments 3 and 6), with sugar cane vinasses (used in all treatments) at presence of commercial probiotics (Bacillus subtilis and Bacillus coagulans) (treatments 1, 2 and 3) and combination of probiotics and halophylic bacteria (treatments 4, 5 and 6) at salinity of 60±5g/L during 42 days. Minimum concentrations of nitrite and nitrate were recorded in treatment 6 and lowest ammonia in treatment 1. The highest floc volume were produced in treatments 2 and 5 (41-48mL/L). In terms of nutritional value, significantly higher protein (20-25%) and ash (75-80%) were detected in treatments 2, 3, 5 and 6. But significantly higher carbohydrate (64%) was detected in treatments 1 and 4. Fatty acid analysis of the bioflocs showed that treatments 2 and 5 had highest PUFA n-3 (32%) and treatments 3 and 6 had significantly higher MUFA (22-25%). Results of this research showed that different carbon sources had significant effect on biofloc quality, but the use of probiotics separately or in combination with halophilic bacteria had no significant effect on biofloc quality.