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Abstract
Summary
A total of 180 random samples of hard, Damietta, kariesh, pickled kariesh cheese, mish and kishk (30 of each) were collected from different localities in Assiut city and transferred in sterile containers to the laboratory to be examined. Each sample was divided into 2 parts, the first part was examined chemically for determination of sod. chloride percentage and the second part was examined microbiologically for Halophilic organisms. The obtained results achieved that the average sod. chloride percentage of the examined hard, Damietta, kariesh, pickled kariesh cheese, mish and kishk were 6.7, 7.4, 5.4, 10.1, 10.6 and 7.7%, respectively.
Enumeration and isolation of Halophilic bacteria were carried on H.A. with 2 different concentrations of sod. chloride. The average counts of Halophilic bacteria on H.A. with 3% NaCl in the examined samples of hard, Damietta, kariesh, pickled kariesh cheese, mish and kishk were 3.5x106, 1.0x108, 4.8x107, 4.3x107, 7.7x108 and 1.2x107/g, respectively, while on H.A. with 10% NaCl the average counts in the examined samples were 8.2x105, 9.4x107, 5.1x106, 1.4x107, 1.4x108 and 7.4x106/g, respectively.
In hard cheese, the identified species of Halophilic bacteria on H.A. with 3% NaCl represented by Bacillus spp. 10 (33.3%), Listeria spp. 14 (46.7%), E.coli 2 (6.7%), Micrococcus spp. 4 (13.3%), Vibrio spp. 7 (23.3%), Proteus spp. 11 (36.7%), Pseudomonas spp. and Serratia spp. 5 (16.7% each). While, on H.A. with 10% NaCl the isolated Halophilic bacteria were Bacillus, Listeria, Proteus, Serratia and Halomonas spp. with incidences of 1 (3.3%), 7 (23.3%), 7 (23.3%), 4 (13.3%) and 1 (3.3%), respectively. Further classification of Bacillus spp. revealed that B.cereus, B.subtilis, B.circulans 1 (3.3% each), B.coagulans, B.marinus 2 (6.7% each) and B.schlegelii 5 (16.7%) were recovered from H.A. with 3% NaCl, while only B.schlegelii isolated from H.A. with 10% NaCl with an incidence of 1 (3.3%). The isolated strains of Listeria spp. recovered from H.A. with 3 and 10% NaCl were L.innocua 9 (30.0%) and 0, L.seeligeri 0 and 1 (3.3%), L.welshimeri 3 (10.0%) and 1(3.3%), L.grayi 12 (40.0%) and 5 (16.7%) & L.murrayi 1(3.3%) and 0, respectively.
Concerning Damietta cheese samples, Halophilic bacteria were recovered from H.A. with 3 and 10% NaCl included Bacillus spp. 9 (30.0%) and 1 (3.3%), Listeria spp. 5 (16.7%) and 2 (6.7%), E.coli 1 (3.3%) and 0, Staph. aureus 3 (10.0%) and 1(3.3%), Staph. epidermidis 2 (6.7%) and 1 (3.3%), Micrococcus spp. 3 (10.0%) and 1 (3.3%), Vibrio spp. 9 (30.0%) and 7 (23.3%), Pseudomonas spp. 3 (10.0%) and 2 (6.7%), Proteus spp. 4 (13.3% each), Serratia spp. 4 (13.3%) and 3 (10.0%) & Halomonas spp. 3 (10.0%) and 2 (6.7%), respectively. Also, Flavobacter spp. isolated from Damietta cheese and were recovered only from H.A. with 10% NaCl with an incidence of 2 (6.7%) samples. In addition, Bacillus spp. isolated from Damietta cheese were represented by B.circulans 2 (6.7%), B.firmus, B.marinus, B.pantothenticus 1 (3.3% each) and B.schlegelii 5 (16.7%) on H.A. with 3% NaCl, while only B.polymexa 1 (3.3%) recovered from H.A. with 10% NaCl. Further classification of Listeria spp. revealed that L.monocytogenes, L.welshimeri and L.grayi were the identified species on H.A. with 3% NaCl with incidences of 1 (3.3%), 1 (3.3%) and 4 (13.3%), respectively, while on H.A. with 10% NaCl the incidences were 0, 1 (3.3) and 1 (3.3%), respectively.
About kariesh cheese samples, Halophilic bacteria recovered from H.A. with 3 and 10% NaCl included Bacillus spp. 2 (6.7% each), Listeria spp. 5 (16.7%) and 2 (6.7%), E.coli 7 (23.3%) and 4 (13.3%), Staph. aureus 1(3.3%) and 0, Micrococcus spp. and Enterococci spp. 1 (3.3% each), Vibrio spp. 8 (26.7%) and 6 (20.0%), Pseudomonas spp. 8 (26.7%) and 2 (6.7%), Proteus spp. 11(36.7%) and 1 (3.3%), Serratia spp. 6 (20.0%) and 4 (13.3%) & Halomonas spp. 2 (6.7% each), respectively. The identified Bacillus spp. were B.cereus, B.thuringienesis and B.schlegelii on H.A. with 3% NaCl with incidences of 1(3.3%), 1(3.3%) and 2 (6.7%), respectively, while B.coagulans and B.schlegelii 1 (3.3% each) recovered from H.A. with 10% NaCl. Moreover, classification of Listeria spp. revealed that L.monocytogenes, L.welshimeri and L.grayi were the identified species on H.A. with 3% NaCl with incidences of 1 (3.3%), 3 (10.0%) and 2 (6.7%), while on H.A. with 10% NaCl the incidences were 0, 1 (3.3%) and 1 (3.3%), respectively.
The isolated Halophilic bacteria in the examined pickled kariesh cheese samples by H.A. with 3 and 10% NaCl were identified as Bacillus spp. 18 (60.0%) and 7 (23.3%), Listeria spp. 8 (26.7%) and 2 (6.7%), Vibrio spp. 7 (23.3%) and 5 (16.7%) & Pseudomonas spp. 12 (40.0%) and 2 (6.7%), respectively. While, E.coli 3 (10.0%), Staph. epidermidis & Enterococci spp. 1 (3.3% each), Proteus spp. 4 (13.3%), Serratia spp. 8 (26.7%) and Halomonas spp. 2 (6.7%) were isolated only from H.A. with 3% NaCl. However, Micrococcus spp. isolated only from H.A. with 10% NaCl with an incidence of 1 (3.3%). The identified strains of Bacillus spp. were B.cereus, B.subtilis 1 (3.3% each), B. licheniformis, B.firmus and B.marinus 3 (10.0% each) on H.A. with 3% NaCl. While, B.coagulans 6 (20.0%) and 1 (3.3%), B. thuringienesis 1(3.3% each) & B.schlegelii 13 (43.3%) and 5 (16.7%) on H.A. with 3 and 10% NaCl, respectively. Moreover, L.ivanovii 1 (3.3%) and L.grayi 7 (23.3%) were the only identified strains of Listeria spp. from H.A. with 3% NaCl. On H.A. with 10% NaCl only L.grayi was identified with an incidence of 2 (6.7%).
The isolated Halophilic bacteria in mish samples were included Bacillus spp. 17 (56.7%), Listeria spp. & E.coli 4 (13.3% each), Staph.aureus 2 (6.7%), Staph.epidermidis 3 (10.0%), Micrococcus spp. 1 (3.3%), Vibrio spp. 13 (43.3%), Pseudomonas spp. 4 (13.3%), Proteus spp. 9 (30.0%), Serratia spp. 5 (16.7%) and Halomonas spp. 6 (20.0%) on H.A. with 3% NaCl. While on H.A. with 10% NaCl Bacillus spp.& Listeria spp. 4 (13.3% each), Staph.epidermidis, Pseudomonas spp., Halomonas spp. 1 (3.3% each), Vibrio spp. 2 (6.7%) and Proteus spp. 6 (20.0%) were recovered. In addition, Bacillus strains recovered from H.A. with 3% NaCl included B.cereus 2 (6.7%), B.subtilis, B.licheniformis, B.mycoides, B.circulans, B.firmus & B.thuringienesis 1 (3.3% each), B.coagulans 4 (13.3%), B.marinus 3 (10.0%) and B.schlegelii 9 (30.0%). While on H.A. with 10% NaCl B.licheniformis, B.mycoides, B.circulans and B.schlegelii were existed each in one sample (3.3% each). The identified Listeria spp. were L.monocytogenes & L.welshimeri 1 (3.3% each) and L.grayi 2 (6.7%) on H.A. with 3% NaCl, while on H.A. with 10% NaCl the incidences were 0, 1 (3.3%) and 3 (10.0%), respectively.
Regarding kishk samples the isolated Halophilic bacteria were Bacillus spp. 25 (83.3%), Listeria spp. 4 (13.3%), Vibrio spp. 7 (23.3%), Pseudomonas spp. 8 (26.7%), Proteus spp. 1 (3.3%), Serratia spp. 5 (16.7%) and Halomonas spp. 6 (20.0%) on H.A. with 3% NaCl. However, Bacillus, Micrococcus, Enterococci, Vibrio, Pseudomonas, Proteus and Halomonas spp. recovered from H.A. with 10% NaCl with incidences of 8 (26.7%), 1 (3.3%), 1 (3.3%),3 (10.0%), 3 (10.0%), 2 (6.7%) and 1 (3.3%), respectively. Further classification of Bacillus spp. verifying that B.cereus, B.subtilis, B.coagulans, B.marinus, B.firmus and B.schlegelii were recovered from H.A. with 3% NaCl with incidences of 1 (3.3%), 2 (6.7%), 7 (23.3%), 8 (26.7%), 1 (3.3%) and 22 (73.3%), respectively. While only B.coagulans, B.marinus & B.schlegelii 2 (6.7% each), B.mycoides and B.firmus 1 (3.3% each) were identified on H.A. with 10% NaCl. On the other hand, L.grayi and L.murrayi recovered only from H.A. with 3% NaCl with incidences of 3 (10.0%) and 1 (3.3%), respectively.
The incidence of anaerobic Halophilic bacteria (Clostridium spp.) in examined hard, Damietta, kariesh, pickled kariesh cheese, mish and kishk samples were 96.7, 76.7, 100, 93.3, 90.0 and 96.7%, respectively. In addition, the average counts of Halophilic fungi on MY12%G-3%NaCl were 1.1x105, 2.3x106, 9.9x105, 2.3x105, 2.2x106 and 3.3x105/g, while on MY12%G-10%NaCl the average counts were 1.1x105, 1.1x106, 4.3x105, 7.9x104, 2.2x106 and 3.6x104 in the examined products, respectively.
The public health importance and the steps, which should be taken to control this group of organisms in the dairy industry, as well as, the recommended sanitary measures, were also discussed.