Pengaruh faktor fisikokimia terhadap pembentukan pigmen oleh bakteri laut Mesophilobacter sp.

Abstract

It has been conducted an observations on the effect of environmental factors especially physicochemical factors on the growth and pigment formation by a marine bacteria Mesophilobacter sp. The objectives of this research were to study the effect of : 1) cultivation temperature (25oC, 30oC and 35oC); 2) pH of growth medium (5, 7, and 9); 3) salinity of growth medium (0 ppt, 10 ppt, 20 ppt, 30 ppt and 40 ppt), 4) carbon sources (glucose, acetate, citrate, and maltose), and 5) nitrogen sources (peptone, yeast extract, sodium nitrate, and ammonium sulfate) on the growth of bacteria and the pigment formation. Bacteria were cultivated in 500 ml flasks with a working volume of 250 ml in marine broth and incubated on a shaker incubator with the agitation speed of 120 rpm for seven days. Variables that were observed during the cultivation process involved bacterial growth (cell concentration), pigment concentration, and pH. Observations were carried out up to 168 hours. The cell and pigment concentrations were monitored spectrophotometrically. The results indicated that Mesophilobacter sp. grew well and formed the highest concentration of pigment (P) at temperature 30oC, with value of P 0.12 + 0.003 (λ 463 nm). At pH experiment the highest average P was obtained from medium with pH 9 was 0.14 + 0.006 (λ 463 nm) and significantly different from pH 7 (p <0.5). At salinity experiment, the highest average P obtained from the growth medium with 10 ppt salinity is 3.54 + 0.11 in λ 368 nm. At carbon source experiment, the highest average of P were obtained from maltose, with value 12.13 + 1.33 (λ 232 nm) and 15.86 + 0.52 (λ 258 nm), while in λ 312 nm, λ 368 nm and λ 656 nm that obtained from glucose were 11.59 + 0.28, 7.22 + 0.44 and 1.50 + 0.05. At nitrogen source experiment, the result showed that Mesophilobacter sp. grew rapidly in the medium with yeast extract. The pigment has a maximum absorbance at five wavelengths, namely λ 232 nm, 258 nm, 312 nm, 368 nm, and 658 nm. The average concentration of cells and pigment, showed that yeast extract is the best nitrogen source in cell growth and pigment formation (p <0.05). The highest average P is 12.49 + 0.22 (λ 232 nm); 12.86 + 0.21 (λ 258 nm); 11.09 + 0.56 (λ 312 nm) ; 11.88 + 0.97 (λ 368 nm) and 1.29 + 0.04 (λ 656 nm).