Effect of lactic acid bacteria and the potential probiotic Hafnia alvei on growth and survival rates of narrow clawed crayfish (Astacus leptodactylus Esch., 1823) stage II juveniles

The aim of this study was to screen potential probiotic bacteria against Aeromonas hydrophila and determine the effects of antagonistic bacteria and a commercial product containing lactic acid bacteria on the survival and growth of stage II Astacus leptodactylus juveniles. For this purpose, a total of 110 bacterial strains were isolated from adult, stage II crayfish juveniles and rearing water screened for antagonistic activities against A. hydrophila with well diffusion agar assay. Hafnia alvei strain from stage II crayfish juveniles displayed the inhibition zone (10mm) against A. hydrophila. The experiment was conducted in a completely randomized design with four treatments for 60 days: (I) crayfish fed with live food without probiotics (control group); (II) crayfish fed with live food enriched with lactic acid bacteria (0.015 gL^-1); (III) crayfish fed with live food enriched with Hafnia alvei (10^6 CFU mL^−1); (IV) crayfish fed with control diet and H. alvei added to rearing water (10^6 CFU mL^−1). As a result of this study, lactic acid bacteria and Hafnia alvei applications did not positively affect growth and survival of stage II A. leptodactylus juveniles. In the future, studies on screening potential probiotic bacteria should be used in vitro and in vivo tests. In addition, it will be useful to investigate the lactic acid bacteria and Bacillus spp. from indigenous microflora of crayfish

Effects of different drying temperatures on the physical and mechanical properties of some marbles (Muğla, Turkey) during salt crystallization tests

This study aims to understand the effects of drying temperatures during sodium sulphate salt crystallization tests on the physico-mechanical properties of some Mug. la marbles. Four commercially available and extensively used Turkish marbles, namely Mug. la white, Milas white, Derebag white and Milas Pearl, having different textural properties were subjected to sodium sulphate salt crystallization tests with 30, 60 and 100 degrees C drying temperatures. The change in the physico-mechanical properties of the marbles including weight, dry and saturated unit weights, water absorption, effective porosity, dry and saturated sonic velocities and dry uniaxial compressive strength has been determined for various stages of the salt crystallization tests. The results were evaluated in terms of drying temperatures and the textural properties of the marbles. Based on the test results, the salt crystallization with the drying temperature of 100 degrees C causes significant damage to all marbles. However, the drying temperature of the test at 60 degrees C gives rise to moderate damage, whereas the drying of the marbles at 30 degrees C gives the least damage. Therefore, the drying temperature of the salt crystallization tests should be less than 60 degrees C and preferably around 30 degrees C in order to avoid additional thermal effects on marbles. Furthermore, the fine-gained Milas pearl marble with irregular grain boundary is found to be the most resistant one against the salt crystallization