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Characterization of a Bioflocculant (MBF-UFH) Produced by Bacillus sp. AEMREG7.

Okaiyeto K, Nwodo UU, Mabinya LV, Okoli AS, Okoh AI - Int J Mol Sci (2015)

Bottom Line: The production of the bioflocculant was observed to be closely associated with cell growth.The bioflocculant retained high flocculating activity of 90% after heating at 100 °C for 1 h.MBF-UFH appears to have immense potential as an alternative to conventional chemical flocculants.

View Article: PubMed Central - PubMed

Affiliation: South Africa-Medical Research Council (SA-MRC), Microbial Water Quality Monitoring Centre, University of Fort Hare, 5700 Alice, South Africa. okaiyetofranciskunle@yahoo.ca.

ABSTRACT
A bioflocculant named MBF-UFH produced by a Bacillus species isolated from sediment samples of Algoa Bay of the Eastern Cape Province of South Africa was characterized. The bacterial identification was through 16S rDNA sequencing; nucleotide sequences were deposited in GenBank as Bacillus sp. AEMREG7 with Accession Number KP659187. The production of the bioflocculant was observed to be closely associated with cell growth. The bioflocculant had the highest flocculating activity of 83.2% after 72 h of cultivation, and approximately 1.6 g of purified MBF-UFH was recovered from 1 L of fermentation broth. Its chemical analyses indicated that it is a glycoprotein composed of polysaccharide (76%) and protein (14%). Fourier transform infrared spectroscopy (FTIR) revealed that it consisted of hydroxyl, amide, carboxyl and methoxyl as the functional moieties. Scanning electron microscopy (SEM) revealed the amorphous structure of MBF-UFH and flocculated kaolin clay particles. The maximum flocculating activity of 92.6% against kaolin clay suspension was achieved at 0.3 mg/mL over pH ranges of 3-11 with the peak flocculating rate at pH 8 in the presence of MgCl2. The bioflocculant retained high flocculating activity of 90% after heating at 100 °C for 1 h. MBF-UFH appears to have immense potential as an alternative to conventional chemical flocculants.

No MeSH data available.


Time course of bioflocculant production by Bacillus sp. AEMREG7.
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ijms-16-12986-f001: Time course of bioflocculant production by Bacillus sp. AEMREG7.

Mentions: Figure 1 shows the relationship between MBF-UFH production and cell growth over a cultivation time of 192 h. Most microorganisms produced bioflocculant during the exponential growth phase [12]. The flocculating activity of the bioflocculant increased gradually with an increase in cultivation time. Generally, the production of MBF-UFH by Bacillus sp. AEMREG7 was observed to correspond with cell growth. Nonetheless, the highest flocculating activity of 83% was attained at 72 h in the late exponential growth phase, thus indicating that the production of MBF-UFH was closely associated with cell growth [21]. However, the decrease in the flocculating activity observed after 72 h may be due to the deflocculating enzyme released by the microorganism during the death phase of the cells. These results were similar to the findings of Wu and Ye [22] in which the bioflocculant production was synchronous with cell growth and reached maximum flocculating activity in the late logarithmic growth phase and early stationary phase. Furthermore, an increase in cultivation time led to a decrease in bioflocculant production as the flocculating activity decreased steadily. This decrease in flocculating activity of MBF-UFH might be due to deflocculating enzymatic activities or accumulation of toxic metabolic wastes affecting the produced bioflocculant [9]. Therefore, a cultivation time of 72 h was chosen for the subsequent experiments. It is apparent that MBF-UFH biosynthesis occurred during different microbial growth phases for different organisms [23]. Additionally, under optimum culture conditions, about 1.6 g of purified MBF-UFH was recovered from 1 L of fermentation broth of Bacillus sp. AEMREG7, which is higher than 0.4 g of the purified bioflocculant produced by Aspergillus flavus [24]. On the contrary, the bioflocculant production by Chryseobacterium daeguense W6 was released into the culture broth in the death phase of cell growth, when the nutrient in the medium had been depleted [10].


Characterization of a Bioflocculant (MBF-UFH) Produced by Bacillus sp. AEMREG7.

Okaiyeto K, Nwodo UU, Mabinya LV, Okoli AS, Okoh AI - Int J Mol Sci (2015)

Time course of bioflocculant production by Bacillus sp. AEMREG7.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490482&req=5

ijms-16-12986-f001: Time course of bioflocculant production by Bacillus sp. AEMREG7.
Mentions: Figure 1 shows the relationship between MBF-UFH production and cell growth over a cultivation time of 192 h. Most microorganisms produced bioflocculant during the exponential growth phase [12]. The flocculating activity of the bioflocculant increased gradually with an increase in cultivation time. Generally, the production of MBF-UFH by Bacillus sp. AEMREG7 was observed to correspond with cell growth. Nonetheless, the highest flocculating activity of 83% was attained at 72 h in the late exponential growth phase, thus indicating that the production of MBF-UFH was closely associated with cell growth [21]. However, the decrease in the flocculating activity observed after 72 h may be due to the deflocculating enzyme released by the microorganism during the death phase of the cells. These results were similar to the findings of Wu and Ye [22] in which the bioflocculant production was synchronous with cell growth and reached maximum flocculating activity in the late logarithmic growth phase and early stationary phase. Furthermore, an increase in cultivation time led to a decrease in bioflocculant production as the flocculating activity decreased steadily. This decrease in flocculating activity of MBF-UFH might be due to deflocculating enzymatic activities or accumulation of toxic metabolic wastes affecting the produced bioflocculant [9]. Therefore, a cultivation time of 72 h was chosen for the subsequent experiments. It is apparent that MBF-UFH biosynthesis occurred during different microbial growth phases for different organisms [23]. Additionally, under optimum culture conditions, about 1.6 g of purified MBF-UFH was recovered from 1 L of fermentation broth of Bacillus sp. AEMREG7, which is higher than 0.4 g of the purified bioflocculant produced by Aspergillus flavus [24]. On the contrary, the bioflocculant production by Chryseobacterium daeguense W6 was released into the culture broth in the death phase of cell growth, when the nutrient in the medium had been depleted [10].

Bottom Line: The production of the bioflocculant was observed to be closely associated with cell growth.The bioflocculant retained high flocculating activity of 90% after heating at 100 °C for 1 h.MBF-UFH appears to have immense potential as an alternative to conventional chemical flocculants.

View Article: PubMed Central - PubMed

Affiliation: South Africa-Medical Research Council (SA-MRC), Microbial Water Quality Monitoring Centre, University of Fort Hare, 5700 Alice, South Africa. okaiyetofranciskunle@yahoo.ca.

ABSTRACT
A bioflocculant named MBF-UFH produced by a Bacillus species isolated from sediment samples of Algoa Bay of the Eastern Cape Province of South Africa was characterized. The bacterial identification was through 16S rDNA sequencing; nucleotide sequences were deposited in GenBank as Bacillus sp. AEMREG7 with Accession Number KP659187. The production of the bioflocculant was observed to be closely associated with cell growth. The bioflocculant had the highest flocculating activity of 83.2% after 72 h of cultivation, and approximately 1.6 g of purified MBF-UFH was recovered from 1 L of fermentation broth. Its chemical analyses indicated that it is a glycoprotein composed of polysaccharide (76%) and protein (14%). Fourier transform infrared spectroscopy (FTIR) revealed that it consisted of hydroxyl, amide, carboxyl and methoxyl as the functional moieties. Scanning electron microscopy (SEM) revealed the amorphous structure of MBF-UFH and flocculated kaolin clay particles. The maximum flocculating activity of 92.6% against kaolin clay suspension was achieved at 0.3 mg/mL over pH ranges of 3-11 with the peak flocculating rate at pH 8 in the presence of MgCl2. The bioflocculant retained high flocculating activity of 90% after heating at 100 °C for 1 h. MBF-UFH appears to have immense potential as an alternative to conventional chemical flocculants.

No MeSH data available.