NewBioWorld A
Journal of Alumni Association of Biotechnology (2020) 2(1):28-32
RESEARCH
ARTICLE
Biosorption of Iron by pretreated fungal biomass of Aspergillus niger and Aspergillus flavus
Tikendra Kumar Verma1*, Vijeyata Verma2,
S.K. Jadhav3
1Laxman
Prasad Baidh Govt. Girls College, Bemetara, Chhattisgarh, India
2Department
of KriyaSharir, N.P.A. Govt. Ayurved College, Raipur, Chhattisgarh, India
3School of
Studies in Biotechnology, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh,
India
Email: tiken03ymail.com;
drvijeyataverma@gmail.com; jadhav9862@gmail.com
*Corresponding Author Email- tiken03@ymail.com
ARTICLE INFORMATION
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ABSTRACT
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Article history:
Received
25 November 2019
Received in revised form
18 January 2020
Accepted
Keywords:
Iron;
pretreatment;
biosorption
capacity; Aspergillus niger; Aspergillus flavus
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The current biotechnology situation involves the
discovery of a novel class of biosorbents with a high capacity for heavy
metal removal. Iron (Fe2+) is one of the heavy metal, which is
commonly found in earth’s crust and also in industrial process like a mining
operation, steel and ferroalloy based industrial effluents. In the present
study, The ability of Aspergillus
niger and Aspergillus flavus
fungal biomass to biosorption of iron was examined in relation to the effects of
physical pretreatment such as heat, autoclaving, freeze-drying, and chemical
pretreatment such as sodium hydroxide, commercial laundry detergent,
formaldehyde, acetic acid, and dimethyl sulfoxide. In comparison to live
biomass, the maximum biosorption capacity of A. niger and A. flavus biomass
after physical pretreatment, subjected to freeze drying, was 1.79 mg/0.1 g
and 1.04 mg/0.1 g, respectively. After chemical pretreatment, subjected to
acetic acid, it was 1.89 mg/0.1 g and 1.61 mg/0.1 g.
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Introduction
The
unceasing growth of industrialization and urbanization has increased the demand
for natural resources. These kinds of human activities have also increased the
level of pollution in the present environment day by day. One of the major
pollution in present scenario is water pollution, which is due to the disposal
of industrial effluent or domestic wastewater, many of which contains high
levels of toxic substances including heavy metals. The metals such as Fe, Cu,
Zn, Mn, Pb, Hg, Cd and Cr etc. are widely distributed into earth’s surface.
These metal species are mobile in nature, which are released into the
environment by technological activities of human incline to keep on completely
accumulating throughout the food chain, ecosystem, humans and animals (Volesky
and Holan, 1995).Iron is one of the heavy metal, which is widely used in
electroplating industries, steel and ferroalloy units etc. Almost all organisms
and living cell require iron for the basic cellular process. However, excessive
iron causes iron toxicity. In humans, vomiting, diarrhea and damage in the
intestine are the symptoms of iron toxicity and it is also affecting the
aquatic life through getting precipitated in the gills of fishes (Binupriya et
al., 2006).These are a serious concern to seek a solution for the removal of
toxic elements from living organisms and provide them a healthy life cycle.
DOI: 10.52228/NBW-JAAB.2020-2-1-6
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“Biosorption may be simply defined as the removal of substances from
solution by biological material” (Gadd, 2009). There are various types of a
biological system like bacteria, yeast, algae and fungi etc. are already
investigated to remove heavy metals from aqueous solutions according to Wang
and Chen (2009). Apart from these, fungi have a great potential to remove
metallic substances, due to their easy availability, inexpensive growth media
and lower maintenance, relatively to other biomaterials (Viraraghavan and
Srinivasan, 2011).Huang and Huang (1996) suggested that pretreatment of fungal
biomass increased the metal biosorption capacity due to the removal of surface
impurities which reveals the available sites for metal binding. The present
study investigates the use of biomass of two fungal species known as Aspergillus nige rand Aspergillus flavus for the biosorption
of iron. The effects of different physical and chemical pretreatment of above fungal
species on biosorption of iron (Fe2+) were investigated.
Methods and material
Preparation of biomass and pretreatment
The
effluent from the steel industries was use for isolation of fungi. The fungi
were isolated by serial dilution technique on Potato Dextrose Agar (PDA) and
pure isolates were identified as Aspergillus
niger and Aspergillus flavus on the
basis of morphological and microscopic characteristics. These fungal cultures
were routinely maintained on PDA. A liquid medium (YPG) (Yan and Viraraghavan,
2000) with pH value adjusted to 4.5 was prepared, which contains the following:
yeast 3 gℓ-1, peptone 10 gℓ-1 and glucose 20 gℓ-1
for the production of fungal biomass. The culture was grown at 27°C in the
medium in conical flasks kept on a rotary shaking incubator at 100 rpm for
7days. All culture works were done in the sterile condition. Fungal biomass was
harvested by filtering the growth media through Whatman No. 1 filter paper for
biosorption studies.
The
harvested biomass washed with a generous amount of distilled water properly.
The live biomass thus obtained was referred as Type A. After that, 15 g of Type
A was pretreated with different physical and chemical methods as follow:
Physical treatment
·
Only dried at 60°C for 15h
in a drying oven (Type B).
·
Autoclaved for 30 min. at
121°C, 15 psi (Type C).
·
Freeze-dried using liquid
nitrogen to grind it (Type D).
Chemical treatment
·
250 ml of 0.5 N Sodium
Hydroxide Solution (Type E) was boiled for 15 minutes.
·
250 ml of water containing
1.25 g of commercial laundry detergent (Type F) was boiled for 15 minutes.
·
250 ml of formaldehyde
solution (Type G), 15% (vol/vol), boiled for 15 minutes.
·
200 ml of 10% (vol/vol)
acetic acid solution (Type H) were boiled for 15 minutes.
·
200 ml of 50% (vol/vol)
dimethyl sulfoxide solution (Type I) were boiled for 15 minutes.
After each
pretreatment with chemicals, the biomass was washed with a generous amount of
distilled water and then dried at 60°C in a drying oven for 15h. Sodium
hydroxide pretreated biomass was washed with distilled water up to the pH of
the wash solution was near in neutral range (pH 6.8-7.2). Dried biomass was
ground using mortar pestle.
Biosorption studies
Biosorption
experiment carried out using iron (Fe2+) containing solution (in the
form of Ammonium ferrous sulfate [(NH4)2Fe(SO4)2.6H2O])
prepared in distilled water and the initial metal ion concentration was
approximately 5 mgℓ-1 in the solution. Each type of pretreated
biomass (0.1g) was added to 50 mℓ of iron solution at pH 5.5. On a rotary
shaker, the reaction mixture was stirred at a speed of 100 rpm. After 15 hours
of contact, the reaction mixture was filtered using Whatman No. 1 filter paper
to separate the biomass, and the iron content of the filtrate solution was
assessed. Iron concentration was measured using an Iron test kit (Iron Test
0.005-5.00 mgℓ-1, Merck, Germany) and its absorbance level was measured by
Spectroquant NOVA 60 (Merck, Germany). Biosorption experiment was performed in
duplicates and average values were used in the analysis. The following equation
was used to compute biosorption capacity, or the amount of metal ion (mg) that
was biosorbed into each gramme (dry weight) of biomass:
Q = (Ci – Cf /m) V
Where, Q = amount of metal ion bisorbed per g
of biomass (mg); Ci=
initial metal ion concentration (mgℓ-1); Cf= final metal ion concentration (mgℓ-1); m = mass of biomass in the reaction
mixture (g); V = volume of the
reaction mixture (ℓ), (Kapoor and Viraraghavan, 1997).
Results
The live
biomass of A. niger (0.91mg/0.1g) showed
the highest biosorption capacity for Fe2+ ions in comparison with A. flavus (0.84 mg/0.1g). In comparison
to live biomass, the biosorption of iron either increased or reduced depending
on the pretreatment method. The results related to Fe2+ biosorption
by live and pretreated fungal biomass of A.
niger are presented in Figure 1. Pretreatment of live biomass using all
method heat, autoclaved, freeze-dried, NaOH, detergent, formaldehyde, acetic
acid and DMSO resulted in an enhancement of iron biosorption by A. niger compared to live biomass (from
0.91to 1.34-1.89 mg/0.1g).
The results
of pretreatment of A. flavus related
to biosorption of iron were shown in Figure 2. Pretreatment of biomass using
heat, freeze-dried, formaldehyde, acetic acid and DMSO resulted in an
enhancement of iron biosorption in comparison with live biomass (from 0.84 to
0.97-1.61mg/0.1g) while autoclaved, NaOH and detergent were significantly
reduced the iron biosorption by A. flavus
in comparison with live biomass (from 0.84 to 0.37-0.47 mg/0.1g).The actual
enhancement (%) of biosorption of iron by different physically and chemically
pretreated biomass of A. niger and A. flavus was shown in Table 1, in
comparison with live biomass of both fungi, respectively.
Table
1: Actual enhancement (%) of biosorption of iron by pretreated fungal biomass in
comparison with live biomass
Fungal biomass
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Pretreatment
Method
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B
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C
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D
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E
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F
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G
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H
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I
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A. niger
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55.05
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53.39
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97.43
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47.34
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91.38
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93.03
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108.44
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80.37
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A. flavus
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15.48
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-44.05
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23.81
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-55.95
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-48.81
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83.33
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91.67
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64.29
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Figure1: Fe2+biosorption
by live (Type A) and pretreated biomass (TypeB-I) of Aspergillus niger
Figure 2: Fe2+biosorption
by live (Type A) and pretreated biomass (Type B-I) of Aspergillus flavus
Discussion
It was
observed that Q values obtained from all the physically treated biomasses were
high in comparison to live biomass for both fungi A. niger and A. flavus,
except autoclaved biomass (Type C) of A. flavus
obtained low value. Freeze dried biomasses (Type D) showed maximum improvement
on iron biosorption for both fungi A.
niger and A. flavus, from 0.91 to
1.79 mg/0.1g and from 0.84 to 1.04mg/0.1g, respectively. During the process of
freeze drying, several microscopic pores would be formed inside the fungal
biomass due to the formation of ice crystals that channel which provide more
surface area for biosorption. Similar results found by Das et al. (2007) for
cadmium sorption. Cabuk et al. (2005) suggested that the drying and then grinding
of fungal biomass expose more sites for metal binding, therefore, the
probability of seizing metal ions could be increased. The finding showed that
heat and autoclaved biomass of A. niger
increased the biosorption capacity rather than biosorption capacity of A. flavus which reduced in autoclaved
biomass comparison with live biomass, respectively. Yan and Viraraghavan (2000)
also reported that pretreated with autoclaved biomass of Mucor rouxii reduced the biosorption capacity of heavy metal due to
the lake of intracellular uptake. In the same way, Kapoor and Viraraghavan (1998)
reported that A. niger pretreated
with autoclave decreased the biosorption of lead, cadmium, copper and nickel.
The Q
values obtained from all the chemically treated biomasses were maximum in
comparison with live biomass for both fungi A.
niger and A. flavus, except NaOH
and detergent treated biomass (Type E and F) of A. flavus obtained low value. Pretreatment with acetic acid (Type
H) significantly increased biosorption of iron for both fungi A. niger and A. flavus from 0.91 to 1.89 mg/0.1g and from 0.84 to 1.61mg/0.1g,
respectively. Kapoor and Viraraghavan (1998) also reported that A. niger pretreated with acetic acid
enhanced the biosorption capacity of lead and copper. In the same way, Cabuk et
al. (2005) were obtained that acetic acid pretreatment increased biosorption of
lead by fungal biomass of Metarrhizium anisopliae
var anisopliae and Penicillium verrucosum.
Pretreatment of live biomass using formaldehyde (Type G) and DMSO (Type I) also
increased biosorption of iron by A. niger (from 0.91 to 1.64-1.75 mg/0.1g) and
A. flavus (0.84 to 1.38-1.54 mg/0.1g).Similar
improvement in biosorption was reported by Cabuk et al. (2005) for the lead, Kapoor
and Viraraghavan (1998)for lead, cadmium and copper and Ilhan et al.(2004)for
copper metal ion using formaldehyde pretreated biomass. Pretreatment with DMSO of
fungal biomass was also suggested by Kiran et al. (2005) for lead and copper, Cabuk
et al. (2005) for lead and Kapoor and Viraraghavan (1998) for lead, cadmium and
copper to the improvement of biosorption capacity.
Pretreatment
of fungal biomass using NaOH (Type E) and detergent (Type F) were also
increased biosorption capacity of A.
niger (from 0.91 to 1.34-1.74 mg/0.1g)in comparison with live biomass. In
contrast, pretreatment using NaOH and detergent significantly reduced
biosorption capacity of A. flavus in comparison
with live biomass (from 0.84 to 0.43-0.37mg/0.1g). Kapoor and Viraraghavan
(1998) showed that similar results to enhance the biosorption capacity for
lead, cadmium and copper using NaOH and detergent except for nickel biosorption
which reduced in comparison with live biomass.
Yan and
Viraraghavan (2000) suggested that alkali treatment such as NaOH with boiling
caused heavy loss of biomass, therefore, the significant reduction of
biosorption capacity of metal ions in comparison with NaOH with autoclaved biomass.
Most of the detergent also contains alkalis as an ingredient; therefore,
pretreatment with alkaline detergent resulted in an enhancement of biosorption
of metal ions. The fungal species belong to different genera or same genera
have different chemical characteristics in their cell wall composition, which
is one of the reasons why metal biosorption capacities are different from each
other (Ilhan et al., 2004, Cabuk et al., 2005).
Conclusion
Biosorption
capacity of dead fungal biomass may be more useful than the use of live
biomass, depending upon the pretreatment method applied. The findings suggest
that iron can be removed from industrial effluents using biomasses of A. niger and A. flavus that have undergone physical and chemical pretreatment
procedures. Utilizing A. niger that
has already been treated with acetic acid may be useful if the removal of iron
(Fe2+) is necessary. It is also necessary to get the knowledge about
the chemical composition of fungal cell walls, which suits the best combination
of particular metal ions, pretreatment methods and other condition. Furthermore, details study should be required
to understand causes of enhancement or reduction in biosorption capacity of
microbial biomass.
Acknowledgment
The
authors gratefully acknowledge to the funding provided by DST, New Delhi in the
form of DST-FIST (Sl. No. 270 for tenure of 2013-18) and also acknowledge PRSU
Raipur, for providing financial assistance to T. K. Verma in the form of
University Research Fellowship.
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