ScienceAsia 13 (1987): 015-027 |doi: 10.2306/scienceasia1513-1874.1987.13.015

TENTATIVE UTILIZATION OF PHOTOSYNTHETIC BACTERIA AS A MULTIPURPOSE ANIMAL FEED SUPPLEMENT TO FRESH WATER FISH. I. THE UTILIZATION OF RHODOPSEUDOMONAS GELATINOSA FROM CASSAVA SOLID WASTES FOR GOLDFISH, CARASSIUS AURATUS

NAPAVARN NOPARATNARAPORN,^a SAVITR TRAKULNALEUMSAI AND SANTANA DUANGSAWAT^b

ABSTRACT: R. gelatinosacell mass cultivated on cassava solid waste under aerobic - dark condition contained 56% protein, 2.45% fat, 26.42% carbohydrate and 3.21%.ash. The protein. consisted of appreciable amounts of essential amino acids (methionine, lysine, leucine and phenylalanine) comparable with those of other single cell protein (SCP) sources. The contents of vitamins essential for animal feed were appreciable such as: (mg/kg dry cell) vitamin B₂, 33.2; vitamin B₁₂, 33.0; vitamin E, 50.7 and niacin, 135.8. The intracellular content of carotenoid was 0.09 mg/g dry cell.

     The bacterial cell mass was replaced for 50% (w/w dry basis) of the fish meal of the control diet and was fed to 2-month old goldfish, Carassius auratus in moist pellet form for a 122-day feeding period. There was no mortality and no overt toxicity observed with both isonitrogenous diets. Growth of fish fed with bacterial cell-supplemented diet was significantly superior in terms of specific growth rate and percentage weight gain: the latter was increased by as much as 22.62%. The most significant enhancement was in fecundity as measured by ovary weight, and numbers of total, mature and immature eggs, which showed increase of 8.57%, 41.18%, 68.48% and 34.77% repectively. There was no effect on muscle pigmentation, while the skin pigmentation was slightly increased. The overall positive feeding effects suggest that the bacterial cell mass may be useful as a multipurpose - animal feed supplement. However, costs of production must be decreased and longer term toxicity tests need to be performed.

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a Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
b Institute of Inland Fisheries, Ministry of Agriculture, Bangkok 10900, Thailand

Received 20 May 1986