Investigation of Moderately Halophilic Bacteria Causing Deterioration of the Salted Sheep and Goat Skins and Their Extermination via Electric Current Applications

Abstract

Determination of moderately halophilic bacterial counts on thesalted skins and examination of utilization of amino acid andcarbon sources by skin isolates offer important informationabout biodegradation of salted skins. Hence, total counts ofmoderately halophilic bacteria, total counts of proteolytic andlipolytic moderately halophilic bacteria found on the saltedsheep and goat skins belonging to different countries wereexamined in this study. One hundred-thirty seven moderatelyhalophilic bacterial species closely related to species of generaAlkalibacillus, Bacillus, Chromohalobacter, Gracilibacillus,Halomonas, Idiomarina, Marinococcus, Oceanobacillus,Planococcus, Salimicrobium, Salinicoccus, Staphylococcus andSalinivibrio were used to detect utilization of different aminoacids and carbon sources which are related to biodegradation ofskins. The values of pH, moisture contents, ash contents and saltsaturations of these skins were also investigated to understandthe correlation between these parameters and moderatelyhalophilic bacterial activities. All salted skin samples containedmoderately halophilic bacteria, proteolytic and lipolyticmoderately halophilic bacteria in high numbers. Each of 137 testisolates, obtained from the salted sheep and goat skins, useddifferent amino acids found in the skin structure. While 100% ofboth sheep and goat skin isolates utilized L-arginine, 86%, 66%,85%, 64% and 66% of the isolates respectively utilized L-glycine,L-alanine, L-tyrosine, L-proline and L-hydroxyproline aminoacids. Ninety-three percent of the isolates used different carbonsources such as dulcitol (13%), D-sorbitol (29%), L-rhamnose(19%), ribose (52%), salicin (40%), myo-inositol (27%), xylitol(21%), benzoate (18%), propionate (34%), D-melezitose (31%),butanol (20%), propanol (23%), methanol (23%), formate (23%)and tartrate (12%). While pH values, moisture contents, ashcontents and salt saturations of the sheep skins ranged from 6.53 to 8.01, 32 to 68%, 12 to 30% and 58 to 100%, respectively, the pHvalues, moisture contents, ash contents and salt saturations ofthe goat skins were between 6.65-8.06, 34-70%, 11-32% and64-100%, respectively. The values of all skin samples were foundto be suitable for the growth and catabolic activities of thesebacteria. To prevent the growth and activities of moderatelyhalophilic isolates causing skin deterioration, the annihilationeffects of 0.5, 1.0, 1.5 and 2.0 A direct and alternating electriccurrent treatments on the mixed culture of moderately halophilicisolates (Chromohalobacter israelensis, Chromohalobactercanadensis, Halomonas halodenitrificans, Staphylococcusnepalensis and Halomonas halmophila) were also separatelyinvestigated in the present study. Both 0.5, 1.0, 1.5, 2.0 A directand alternating electric current applications used in this studycompletely annihilated the mixed culture of moderately halophilicspoilage microorganisms. As a conclusion, we suggest using lowleveldirect or alternating electric current treatment to eradicateharmful moderately halophilic bacteria in salt which will be usedin brine curing of hides and skins in the leather industry.