Lactose/whey fermentation and single cell protein production by auxotrophic mutants of Schizosaccharomyces pombe

Different auxotrophic mutants of Schizosaccharomyces pombe derived from argon irradiation and ethyl methanesulfonate [EMS] treatments were tested for single cell protein [SCP] production and also for the fermentation of lactose/whey as the agro-industrial wastes produced in very large quantities by the diary industry and often comes to be an environmental threat. Some of these mutants and prototrophic isolates were found to induce high yield of biomass and SCP. In addition, many of isolates, which have a higher yield of biomass, proved to give the highest yield of protein. Fermentation studies of lactose/whey showed that some of auxotrophic mutants could efficiently utilize lactose as a carbon source and grow well in whey medium. Although most of the mutants were significantly assimilated and bioconverted lactose, they significantly decreased residual lactose. Analysis of variance showed significant differences for lactose consumption and residual lactose. Auxotrophic mutants were utilized up to 65% of lactose in whey medium, 71% whey + 0.4% lactose and 76% in whey + 0.4% glucose. The results indicated that the biomass of yeast cells produced by the efficient strains of Schizosaccharomyces pombe through the fermentation of lactose/cheese whey might be considered as a protein source for marine and animal feeding. The utilization of these waste materials decreases pollution problems

Effect of caffeine on base-pair substitution and frameshift mutagenesis induced in salmonella typhimurium

The mutagenicity of caffeine was studied by using 2 different Ames Salmonellamutagenicity tester strains. Three short-term assays [plate incorporation,preincubation and the Ames-fluctuation test] were carried out to evaluate thegenotoxicity of caffeine. The effect of some extracts of the culturalfiltrate of Alternaria eichhorniae on the original strains and theirrevertants was also examined. Mutagenicity data for caffeine demonstrated adose-response at levels that are not excessively toxic to bacteria. In allcases, the addition of preincubation resulted in greater sensitivity thanplate incorporation. Testing conducted with strains that carry the base- pairsubstitutions and frame-shift mutations in different repair backgroundsindicated that the presence of pKM101 and the deletion of the uvr B genefacilitate the detection of caffeine as mutagen. The mutagenic activity ofcaffeine determined by employing Salmonella typhimurium mutagenesis assay[TA1535 and TA97] revealed the mutagenic potency of base-pair substitutions andframe-shift mutations in all assays, without any need for metabolicactivation, indicating the presence of direct-action mutagen

Detection and classification of mutagens with a new salmonella typhimurium tester strains

This paper described a model that relates the actual effect measured in the Salmonella test, i.e. the number of revertants colonies, the number of survivors and their relationship with the dose-response. A detection and classification system for mutagens has been developed using a new tester strain, TA102, this strain contains AT base pairs at the site of the mutation, in contrast to other Salmonella tester strains that detect mutagens damaging GC base pairs. The new strains detects a variety of aldehydes, including petroleum ether and hexane, oxidative mutagen, including phenylhydrazine as well as factory effluents. Most of these mutagens as well as factory effluents demonstrate a linear dose response for revertants induced over the spontaneous value which is evidence for mutagenicity and also for cell survivors at levels that are not excessively toxic to the bacteria. All of compounds tested on the bacteria resulted in negative and positive correlation for cell survivors and revertants induced, respectively

Ames fluctuation tests are more sensitive than plate tests in detects ecotoxicological and mutagenicity of factory effluents

In this study, an ecotoxicological and mutagenic characterization of liquid industrial wastes from Fertilizer Factory [FF] and Oils and Soap Company [OSC] has been performed using 3 short-term assays [the incorpo-Ames-fluctuation test, plate ration and preincubation tests] with Salmonella TA strains and E. coli. The expression of ecotoxicity data in terms of survivors demonstrate the dose-response toxic range for both effluents. The strains TA102 and TA1537 were found to be more sensitive to FF effluents-induced mutagenesis in a plate assays as well as TA102 and TA1538 with OSC effluents. The effluents of OSC was found to be excessively toxic to the revertants of TA1537. In the fluctuation tests, the maximum sensitivity for mutagenicity was achieved by the effluents of OSC other than of FF; in contrast, the effluents of FF were found to be weakly mutagenic and strongly toxic other than the wastes of OSC. However, the fluctuation technique using modified media was shown to detect a wider range of mutagenic effect of effluents than tests with standard media