JWSS - Journal of Water and Soil Science

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Carotenoids are one of the most important and widely distributed pigments in nature and have essential biological functions in organisms. They also impart distinctive and attractive coloration to the breeding animals. Over the past two decades, application of microbial carotenoids has attracted the attention of researchers due to their natural and economic advantages. However, carotenoid producing yeasts with lactose assimilating capacity have rarely been studied and there are few references on the use of lactose as a carbon substrate, such as whey, for the biosynthesis of yeast carotenoids. In this study, a red carotenoid-producing yeast, Rhodotorula acheniorum, was isolated from the sap of birch trees at Masseh Chal in the Taleghan village. The yeast thus isolated was identified through microscopic, macroscopic and biochemical tests.

The yeast has both the abilities of lactose assimilation and carotenoid production. The optimal conditions of culture were determined and maximum biomass and carotenoid production were 9.9 g/lit, 290 µg/g, respectively. Chemical analyses of extracted carotenoids have shown that the major portion of the yeast consists of β-carotene, torulene and torularhodin. With regard to the fact that whey is one of the by-products of cheese industries and that its proper disposal has long been a major problem, the most desirable way of handling this waste is to utilize it as a substrate in the production of useful products such as carotenoids.

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Producing food colors from natural sources, such as tomatoes, which could be used instead of synthetic colors, is important in relation to health and safety aspects of the consumers. In this research, solvent extracting was carried out by using three non-polar solvents, including petrolium ether (bp=55°C), n-hexane (bp=60°C) and a mixture of n-hexane: ethanol: aceton (1:1:2, bp=50°C). Also, two different temperatures (room temperature and boiling point of the solvent) and three different periods of time (2,4 and 6 hours) of extraction were tried. Using mixture of the solvents (at boiling point) for six hours showed to be the optimum conditions for extraction and there were significant differences between this treatment and other conditions for extractions. In addition to the above results, the same volumes of the solvent and samples were found to be the best ratio in comparison with the other volumes ratios. It was significant at P .05.. The yield of color extraction from tomatoes and tomato powder was 0.14 and 0.24% (w/w), respectively. Also, the purity of the extracted color was 82.65% lycopen. The extracted color showed a good stability in sunflower oil for three months at 4°C.

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Iron chlorosis is an important disorder of plane trees (Plantanus orintalis L.) in green space of Isfahan city. Before using reclamation methods for correcting Fe chlorosis, it is necessary to find a suitable index for evaluating plant Fe status. Therefore, activity of glutathione peroxidase (GP) enzyme and concentration of carotenoids and chlorophyll a and b pigments, as physiological indices of active Fe, were compared to total Fe concentration in leaves to evaluate Fe status in plane trees. For this purpose, severity of chlorosis of plane trees at different regions of Isfahan city was recorded. Then, 73 trees with different severity of chlorosis symptoms were selected and their leaves were sampled on July 2009 and 2010. Concentration of Fe, chlorophyll a and b and carotenoids in leaves as well as activity of GP enzyme were measured. Results showed large variation in leaf Fe concentration between young and old leaves and also between leaves with different chlorosis severity symptoms. No correlation was found between leaf Fe chlorophyll concentration and severity of chlorosis symptoms. Also, concentrations of chlorophyll a in young and old leaves with very severe chlorosis symptoms were 44 and 37% smaller than that in young and old leaves with slight chlorosis symptoms, respectively. Concentration of chlorophyll b in young and old leaves with very severe chlorosis symptoms were 40 and 37% smaller than that in young and old leaves with slight chlorosis symptoms, respectively. Concentration of carotenoids varied among young and old leaves with different severity of chlorosis symptoms. Activity of GP in young leaves was also reduced by intensifying severity of chlorosis symptoms. According to the result of the present study, activity of GP enzyme and leaf concentration of carotenoids and chlorophyll a, as suitable physiological indices of active Fe, had close correlation with severity of Fe chlorosis in plane trees. Also, deficiency of active Fe in leaves is a probable reason of chlorosis symptoms in plane trees.