ABSTRACT
The effect of different carbon sources on bacterial cellulose production by Gluconacetobacter xylinus [PTCC 1734] and two newly isolated strains [from vinegar] under static culture conditions was studied
The production of bacterial cellulose was examined in modified Hestrin-Shramm medium by replacing D-glucose with other carbon sources
The results showed that the yield and characteristics of bacterial cellulose were influenced by the type of carbon source. Glycerol gave the highest yield in all of the studied strains [6%, 9.7% and 3.8% for S, A[2] strain and Gluconacetobacter xylinus [PTCC 1134], respectively
The maximum dry bacterial cellulose weight in the glycerol-Icontaining medium is due to A[2] strain [1.9 g I[-1]] in comparison to Gluconacetobacter xylinus as reference strain [0.76 g I[-1]]
Although all of the studied strains were in Gluconacetobacter family, each used different sugars for maximum production after glycerol [mannitol and fructose for two newly isolated strains and glucose for Gluconacetobacter xvlinus]
The maximum moisture content was observed when sucrose and food-grade sucrose were used as carbon source
Contrary to expectations, while the maximum thickness of bacterial cellulose membrane was attained when glycerol was used, bacterial cellulose from glycerol had less moisture content than.the others
The oxidized cellulose showed antibacterial activities, which makes it as a good candidate for food-preservatives
ABSTRACT
Cockroaches were collected from hospitals, houses and poultry sheds in various parts of Isfahan [Iran] and identified to species. In total, seven species of cockroaches in seven genera were identified: Blatta lateralis, Polyphaga aegyptiaca, Arenivaga roseni and Parcoblatta spp. Three species Periplaneta americana, Blattella germanica and Supella longipalpa [Blattidae and Blattellidae] were more abundant than the others. In another study, forty cockroaches were collected from hospitals in two experiments and were studied for the presence of Salmonella spp. Salmonella [Black colonies on SS agar with urease negative] were isolated from about 70% of the cockroaches collected from hospitals. Some of the isolated Salmonella were resistant to antibacterial drugs in a susceptibility test. Isolation of Salmonella from cockroaches collected from hospitals suggests that cockroaches act as natural reservoirs of Salmonella. A second study was conducted to determine if individual B. germanica could transfer Salmonella from an infected food source and then infects uncontaminated colony members. The results showed that the inoculation of 106 CFU of Salmonella into cockroaches via their food could infect the uncontaminated cockroaches. These contaminated cockroaches transfer infection to other colony members. Salmonella is stable in cockroaches for more than 10 months