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    STUDIA BIOLOGIA - Ediţia nr.1 din 2019  
         
  Articol:   THE INFLUENCE OF THE CHLORIDE CONTENT ON THE GROWTH OF HALOPHILIC BACTERIA ISOLATED FROM THE SALINE LAKE LETEA AND THEIR EXTRACELLULAR ENZYMATIC ACTIVITIES .

Autori:  ANCA IOANA LUCACI, ROXANA COJOC, SIMONA NEAGU, ROBERT RUGINESCU, IOAN ARDELEAN, MĂDĂLIN ENACHE. 		 
       
         
  Rezumat:   This paper presents preliminary results of an investigation that had as main objective to quantify the seasonal variations of halophilic bacteria in the saline Lake Letea (Romania), which has an alkaline pH and a salt (chloride) concentration that varies in time, and their ability to produce extracellular hydrolytic enzymes. The investigations were performed from October 2016 until May 2018. Numbers of cultivable putative moderately halophilic bacteria were estimated using culture medium MH with 10% NaCl. The recorded number of colony forming units/mL was between 41 (October 2016) and 3.7x103 (April 2017). After a random selection, colonies were grown for three successive passages for purification, and 82 isolates were investigated. Based on their salt requirement and tolerance, 69 isolates were halotolerant and 13 isolates were moderately halophilic bacteria. The generation time was also determined for several isolates. Seventeen percent of the isolates were oxidase-negative and 83% oxidase-positive. Forty eight percent of isolates were catalase-negative and 52% catalase-positive. Presence of extracellular enzymatic activities was tested using MH medium with salinity varying between 0-4 M and supplemented with a substrate to induce the production of the hydrolases tested. The highest hydrolytic activities were recorded for Tween 80, casein and inulin. This study represents a preliminary investigation of the diversity and extracellular enzymatic activities of halophilic bacteria isolated from Lake Letea .

Keywords: halophilic microorganism, hydrolytic enzymes, screening. 		 
         
     
         
         
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