Four bioagents, Bacillus subtilis, Pseudomonas fluorescence, P. aeruginosa, and Streptomyces spp., were used in vitro and in vivo against two pathogenic isolates of Erwinia carotovora subsp. carotovora (Ecc1 and Ecc2), the causal agent of potato soft rot. In vitro Streptomyces spp. showed the strongest effect against Ecc1 and Ecc2 and gave the highest values of the inhibition zones, being 37 and 40 mm, respectively followed by P. fluorescence, B. subtilis, and P. aeruginosa, where the inhibition zones reached, respectively, 32, 28, and 24 mm against Ecc1 and 35, 29, and 26 mm against Ecc2. Also, these results confirmed those of the in vivo experiment (in pots) since Streptomyces spp. bioagent exhibited the lowest number of infected tubers followed by P. fluorescence, B. subtilis, and P. aeruginosa, respectively, against the two isolates Ecc1 and Ecc2. Also, disease severity of soft rot caused by each of the two isolates, Ecc1 and Ecc2, was decreased by using bioagents, and the lowest disease severity values were obtained by using Streptomyces spp., P. fluorescence, B. subtilis, and P. aeruginosa, respectively.

Keywords:Aquaculture Effluent Reused Environment Adsorbent TreatmentAquaculture is currently the largest source of fish supply in Egypt. However, with this great productivity there has been an obsession with liquid waste and its impact on the environment. The aim of the present work is to make a preliminary trial to evaluate the ability of some low cost materials (sawdust, sawdust ash, granite powder, and crushed granite) to improve the quality of waste effluents resulting from recirculation aquaculture systems, and selecting the most efficient adsorbent to be applied at three different levels to verify which level is the most probable for waste effluent to be reused in fish culture. Total dissolved solids (TDS), electric conductivity (EC), salinity, dissolved oxygen (DO), turbidity, florin (F), chlorine (CL), phosphate (PO 4 ), sulphate (SO 4 ), ammonium (HN 4 ), nitirate (NO 3 ), nitrite (NO 2 ) were the evaluating parameter. Results from the adsorption experiment showed that the crushed granite was a promising adsorbent for aquaculture wastewater treatment. Accordingly, the effect of using different doses (5g/L, 10g/L and 20g/L) of crushed granite on water quality parameters was assessed and surface characteristics of cracked granite were determined using FTIR spectrophotometer for surface functional groups identifications, and X-ray diffraction (XRD) for mineralogical composition and nitrogen absorption for surface porous structure and surface area. Results revealed that crushed granite composed mainly of quartz and that 10g/L of crushed granite is the most probable level to be used with waste effluents for recirculation aquaculture systems.