In this study, 332 lactic acid bacteria of broiler gut origin were investigated as putative probiotic candidates. Sixty-two bacteria showed the highest aggregation while showing antibacterial effects against Salmonella Enteritidis, Salmonella Typhimurium, and Escherichia coli O78:K80. Enzymatic activities of the selected bacteria were examined. No lipase activity was detected, but all of them showed almost similar proteolytic activities. However, they had different amylase and phytase activities. Four of the 62 bacterial strains were selected as a result of aggregation and amylase tests. They were chosen for the following attributes: high cell surface hydrophobicity, co-aggregation, and resistance to bile salts and also acidic conditions. Finally, Lactobacillus crispatus was selected as a source of potential probiotic because of its predominant characteristics in comparison to the other isolated strains from the gastrointestinal tract of chickens. This study has provided a good arrangement of rapid methods for screening a high number of bacteria: a series of beneficial tests that are used together for the first time on chickens, and not any other animals.

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The temperature-induced, over-expression of the human growth hormone gene in a recombinant E. coli during high cell density cultivation is reported. Human growth hormone (hGH) production and stability were tested under different heat shock conditions. Cell densities were 25 and 60 g l(-1) in a pH-stat fed-batch mode in defined and complex medium, respectively, and the fermentation time was decreased from 41 to 32 h. hGH was produced at 2 g l(-1) in complex medium. By using glycerol as main carbon source in the complex medium with exponential feeding, cell density and hGH production were increased to 100 g l(-1) and 2.7 g l(-1), respectively.