Determination of the elemental composition of molasses and its suitability as carbon source for growth of sulphate-reducing bacteria

Discipline of Microbiology, University of KwaZulu-Natal, Private Bag X01, 3209, Pietermaritzburg, South Africa.
Journal of Hazardous Materials (Impact Factor: 4.33). 06/2008; 161(2-3):1157-65. DOI: 10.1016/j.jhazmat.2008.04.120
Source: PubMed

ABSTRACT Bioremediation of arsenic-contaminated water could be a cost-effective process provided a cheap carbon source is used. In this work molasses was tested as a possible source of carbon for the growth of sulphate-reducing bacteria (SRB). Its elemental composition and the tolerance of SRB toward different arsenic species (As (III) and As (V)) were also investigated. Batch studies were carried out to assess the suitability of 1, 2.5 and 5 g/l molasses concentrations for SRB growth. The results indicated that molasses does support SRB growth, the level of response being dependant on the concentration. The percentage of sulphate reduction with molasses at 1, 2.5 and 5 g/l was not significantly different. However, growth on molasses was not as good as that obtained when lactate was used as carbon source. Molasses contained the heavy metals Al, As, Cu, Fe, Mn and Zn in concentrations of 0.54, 0.24, 8.7, 0.35, 11.1 and 19.7 microg/g, respectively. Arsenic tolerance, growth response and sulphate-reducing activity of the SRB were investigated using arsenite and arsenate solutions at final concentrations of 1, 5 and 20 mg/l for each species. The results revealed that very little SRB growth occurred at concentrations of 20 mg/l As(III) or As(V). At lower concentrations (1 mg/l) the SRB grew better with As(V) than with As(III). Arsenic pollution in most groundwater sources is below this level (1 mg/l).

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    ABSTRACT: ABSTRAK: Pertumbuhan Spirulina platensis memerlukan nitrogen, fosfat, dan karbon. Semakin tinggi harga media komersial mendorong dilakukannya pencarian medium alternatif dalam pertumbuhan. Penelitian ini mencoba mengevaluasi rasio C:N dalam media dengan melakukan variasi penambahan molase serta urea untuk sebagai pengganti media komersial. Bibit Spirulina platensis dikultivasi sebagai kontrol yang terdiri dari 1000 ppm NaHCO 3 sebagai sumber karbon, 80 ppm urea sebagai sumber nitrogen, 20 ppm TSP (triple super phosphate) sebagai sumber phosphate, 1ppm FeCl 3 dan 50 µg L-1 vitamin B12 sebagai sumber mikronutrien. Spirulina platensis dikultivasi pada botol erlenmeyer 2 liter dengan mengubah komposisi urea dan molase pada media pertumbuhan dengan menambahkan 20% (w/w) medium kontrol. Urea divariasi antara 0; 16; dan 80 mg L-1. Sedangkan molase divariasi pada level 0,1 sampai 0,9 g L-1. Kondisi operasi selama kultivasi dengan variabel tetap adalah pH 9-10. Intensitas cahaya diatur pada 6000-7000 lux. Pompa mini aerator digunakan sebagai pengaduk media. Salinitas kultivasi dijaga pada kondisi 2 ppt dan suhu dijaga pada kondisi 28-30 0 C. Hasil terbaik diperoleh pada penambahan molase 0,1 g L-1 dengan urea 16 mg L-1 yaitu dengan laju pertumbuhan (growth rate) 0.230 hari-1 , rasio C:N 6,8 dan biomassa kering 0,333 g L-1. Kata Kunci: Spirulina platensis; evaluasi C/N; molase ABSTRACT: Growth of Spirulina platensis requiers nitrogen, phosphate, and carbon. Due to high price of commercial medium, it is necessary to find alternative and cheap medium in Spirulina cultivation. The purpose of this research was to evaluate C:N ratio of medium using different concentration of molase and urea addition as replacement of commercial medium. Spirulina platensis was cultivated as a control consist of 1000 ppm NaHCO 3 as source of carbon, 80 ppm urea as source oh nitrogen, 20 ppm TSP (Triple Super Phosphate) as source of phosphate, 1 ppm FeCl 3 and 50 µg/l B12 vitamin as source of micronutrients. Spirulina platensis was cultivated in 2-liter of erlenmeyer flask with variation composition of urea and molasses in growth media by adding 20% (w/w) control medium. Urea was varied between 0; 16; and 80 mg L-1 , molasses was varied at the level of 0,1-0,9 g L-1. Cultivation was maintained in pH 9-10, light intensity 6000-7000 lux and 28 0 C. Mini aerator pump is used as a medium stirrer. The best result were obtained at the medium varied of 0,1 g L-1 and 16 mg L-1
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