Biomedical subjects

N Jedidi

Publications and source records attributed to N Jedidi.

6 recordsLinked to original sources

PubMed2001

Microbial characterization during composting of municipal solid waste.

This study investigates the prevailing physico-chemical conditions and microbial community; mesophilic bacteria, yeasts and filamentous fungi, bacterial spores, Salmonella and Shigella as well as faecal indicator bacteria: total coliforms, faecal coliforms and faecal Streptococci, present in a compost of municipal solid waste. Investigations were conducted in a semi-industrial pilot plant using a moderate aeration during the composting process. Our results showed that: (i) auto-sterilization induced by relatively high temperatures (60-55 degrees C) caused a significant change in bacterial communities. For instance, Escherichia coli and faecal Streptococci populations decreased, respectively, from 2 x 10(7) to 3.1 x 10(3) and 10(7) to 1.5 x 10(3) cells/g waste dry weight (WDW); yeasts and filamentous fungi decreased from 4.5 x 10(6) to 2.6 x 10(3) cells/g WDW and mesophilic bacteria were reduced from 5.8 x 10(9) to 1.8 x 10(7) bacteria/g WDW. On the other hand, the number of bacterial spores increased at the beginning of the composting process, but after the third week their number decreased notably; (ii) Salmonella disappeared completely from compost by the 25th day as soon as the temperature reached 60 degrees C; and (iii) the bacterial population increased gradually during the cooling phase. While Staphylococci seemed to be the dominant bacteria during the mesophilic phase and at the beginning of the thermophilic phase, bacilli predominated during the remainder of the composting cycle. The appearance of gram-negative rods (opportunistic pathogens) during the cooling phase may represent a serious risk for the sanitary quality of the finished product intended for agronomic reuse. Compost sonication for about 3 min induced the inactivation of delicate bacteria, in particular gram-negatives. By contrast, gram-positive bacteria, especially micrococcus, spores of bacilli, and fungal propagules survived, and reached high concentrations in the compost.

Biodegradation, Environmental↗

PubMedDate not supplied

[Value of waste water in agriculture. Evaluation of soil bacterial contamination, water table and plant culture].

The present study aim was to valorize the treated waste water as source of fertilizers for vegetables seed production and to assess the eventual bacteriological contamination risks of soil, plant and phreatic ground water table. The bacteriological analysis of drained water did not reveal any fecal coliforms vertical migration in depth and a low fecal contamination (thermotolerant coliforms) is limited to the levels of superficial horizons. The seed produced by using waste water showed a slightly fecal contamination which disappeared following treatment with a (5% chloride solution. The treated waste water improve the onion seeds production per hectare in spite of the increases of the phytopathogenic hazards.

Agriculture↗

PubMedDate not supplied

[Cytotoxicity of ferric chloride used as an adjuvant of organic acid precipitation].

The objective of this study was the amelioration of the organic acid precipitation technique currently used as a secondary stage for viruses concentration using ferric chloride (FeCl3) as an adjuvant. To carry out this work successfully, we have studied the cytotoxicity effect of FeCl3 towards cell lines usually used for the investigation of enteric viruses. Two kinds of african green monkey kidney cells, MA104 and BGM, were used as a cellular model. The results showed that optimum concentration of FeCl3 for either BGM or MA104 cell survival and organic acid precipitation varies from 0.5 to 1 mM. The cytotoxicity test used in this work was simple, easy to realize and gives an appreciable information about the cytotoxicity dose of a given biological and chemical product.

Animals↗

PubMedDate not supplied

[A method for recovery of enteroviruses from milk].

A method of detection of enteric viruses in milk was studied. The high protein content of milk and the protein nature of enterovirus allowed the detection of these viruses using the organic acid flocculation method. The poliovirus type 1 (Mahoney strains) and the E.C.H.O.1 isolated from the environment were used as virus model and were inoculated to creamed, half-creamed and whole UHT commercialized milk. The method consists on a milk sample clarification with acid precipitation and centrifugation. The clarified extract is reduced to a final volume of 10 to 15 ml after addition of beef extract powder and protein precipitation. This technique allows the recovery of 26 to 36% of poliovirus type 1 and 10 to 46% of E.C.H.O.1 viruses. In this work, the ferric chloride (FeCl3), added in 0.5 to 1 mM final concentration, was used as an adjuvant for the organic acid precipitation.

Animals↗

PubMedDate not supplied

[Hygienic aspects of aerobic fermentation of urban waste in the Tunisian context].

The use of the aerobic fermentation (composting) as an alternative of the landfilling of the municipal solid wastes was studied in a pilot plant in the District of Tunis. The effectiveness of the composting, by the windrow turning technical, in producing sanitized compost was considered. Fecal coliforms, fecal streptococcis and E. coli were used as an indicator organism. In addition, the evolution of the process was monitored using sporogenous bacteria. Under the experimental conditions, approximately five logarithmic unit reduction of fecal indicators was noted after a 60 days composting.

Aerobiosis↗

PubMedDate not supplied

[Isolation of salmonella in wastewaters and study of indicator bacteria survival in soils].

Detection of salmonella in wastewaters was done in semi-industrial pilot plant. In parallel, survival of indicator bacteria (feacal coliforms and feacal streptococci) in the soil was evaluated into a laboratory incubation device. Results revealed the isolation of 21 strains of salmonella in 7 campaigns of analysis on DCLS media, and 6 strains on lactose-green-brilliant and phenol red media in 2 campaigns. Salmonella were recovered in all the lines of wastewater treatment. The study led on the survival of coliforms and streptococci bacteria allowed the conclusion that feacal streptococci introduced by wastewaters were more qualified to survive in the soil than feacal coliforms. On the other hand, feacal coliforms appeared more sensitive to the biological factors of the soil than feacal streptococci. The ambient temperature of incubation situated between 12 and 24 degrees C seemed suitable for bacteria survival in the soils.

Enterobacter↗