Selection of Rhodobacter sphaeroides P47 as a useful source of single cell protein.

Abstract

Rhodobacter sphaeroides P47 was selected as a potent microorganism for SCP production. The selection criteria were: high growth rate, high growth yield from consumed sugar, ability to consume various sugars, high protein content with a balanced amino acid composition, and acceptable contents of vitamin B12 and carotenoids. When the cells grew aerobically on minimal medium containing glucose, fructose and xylose as sole carbon sources, they grew at the relatively high specific growth rate of 0.12-0.161/hr. Also, the growth yield from sugar, 0.52-0.55 g of cells/g of sugar, was high compared with Rb. sphaeroides S as a standard. In the sugar uptake test, strain P47 not only preferably consumed glucose, fructose, xylose and mannose, but also consumed maltose, sucrose, cellobiose and treharose. Strain S consumed only glucose, fructose, xylose and mannose. Strain P47 cells cultured on pineapple waste medium had a relatively high protein content (66.6%) with balanced amino acid composition. The intracellular contents of vitamins B12 and E and carotenoids were 7.9, 21, and 80 mg/ 100 g of dry cells, respectively. f hese values were considerably higher than those of other photosynthetic bacteria.To be suitable for single cell protein (SCP) production (1), microorganisms should: grow fast with efficient growth yield from carbon substrates; attain a high cell density with diverse substrate utilization; and contain balanced nutrients. Regarding potential microbial resources for SCP, several researchers (2-6) have attempted to cultivate photosynthetic bacteria on agroindustrial waste materials, eg. soybean whey, polluted water from soybean curd manufacture, swine excreta (2), wheat bran (3), soybean waste (5) and cassava starch (6). This should be feasible since the bacteria can grow on various carbon substrates under either phototrophic or heterotrophic conditions and their protein content is relatively high

Chemical composition of Rhodocyclus gelatinosus biomass produced in poultry slaughterhouse wastewater

“…Productivity is typically lower for phototrophic bacteria biomass production than it is for heterotrophic organisms because cell densities achieved are low (Kobayashi and Kurata, 1978;Litchfiled, 1983). This is in agreement with other authors' works carried out with different photosynthetic bacteria Nagai, 1979, Sasaki et al, 1981;Noparatnaraporn et al, 1983;Balloni et al, 1986;Noparatnaraporn and Nagai, 1986;Balloni et al, 1987;Prasertsan et al, 1993 a,b ). Cultivation of Rhodocyclus gelatinosus R 1 in poultry slaughterhouse wastewater was feasible due to the simple incubation conditions (Kobayashi and Kurata, 1978) R. gelatinosus (Sasaki et al, 1981) R. gelatinosus A1 (Sasaki et al, 1981) R. sphaeroides P47 (Noparatnaraporn and Nagai, 1986) …”

“…According to Andriguetto et al (1988), these are considered essential amino acids to lead to a maximum yield in poultry nutrition. R. gelatinosus R 1 biomass amino acid composition was very similar to the findings of other authors for most amino acids, except to methionine and phenylalanine, which were in slightly lower concentrations (Kobayashi and Kurata;1978;Sasaki et al, 1981;Noparatnaraporn and Nagai, 1986). The essential amino acids contents of R. gelatinosus R 1 biomass may be considered similar to those of egg and soybean (Sasaki and Nagai, 1979), algae , yeast, animal and plant proteins (Noparatnaraporn and Nagai, 1986).…”

“…R. gelatinosus R 1 biomass amino acid composition was very similar to the findings of other authors for most amino acids, except to methionine and phenylalanine, which were in slightly lower concentrations (Kobayashi and Kurata;1978;Sasaki et al, 1981;Noparatnaraporn and Nagai, 1986). The essential amino acids contents of R. gelatinosus R 1 biomass may be considered similar to those of egg and soybean (Sasaki and Nagai, 1979), algae , yeast, animal and plant proteins (Noparatnaraporn and Nagai, 1986). Some researchers have investigated photosynthetic bacteria biomass production in industrial effluents, such as sugar refinery wastewater (Balloni et al, 1987), miso factory wastewater (Sasaki et al, 1981) and pineapple peel waste (Noparatnaraporn and Nagai, 1986).…”

“…The essential amino acids contents of R. gelatinosus R 1 biomass may be considered similar to those of egg and soybean (Sasaki and Nagai, 1979), algae , yeast, animal and plant proteins (Noparatnaraporn and Nagai, 1986). Some researchers have investigated photosynthetic bacteria biomass production in industrial effluents, such as sugar refinery wastewater (Balloni et al, 1987), miso factory wastewater (Sasaki et al, 1981) and pineapple peel waste (Noparatnaraporn and Nagai, 1986). While serving as a substrate, the pollutant load of the waste is reduced, as it happens in a sewage treatment.…”

“…Rhodocyclus gelatinosus, a PNSB, is of common occurrence in many industrial effluents where it grows well photoautotrophically because of the ability to hydrolyze starch and gelatin due to peculiar hydrolyzing enzymes it produces. It also produces carotenoid pigments of the spirilloxanthin alternative series, which confers red color to its cultures (Trüper and Imhoff, 1992;Brock et al, 1994;Holt et al, 1994) and may find application in animal feed due to the possibility of intensifying animal tissue color (Kobayashi and Kurata, 1978;Noparatnaraporn and Nagai, 1986). This work investigated the chemical composition of Rhodocyclus gelatinosus biomass produced in poultry slaughterhouse wastewater aiming at a further use in the supplementation of broiler and laying hens rations.…”