Exploration of bioactive compounds and antibacterial activity of marine blue-green microalgae (Oscillatoria sp.) isolated from coastal region of west Malaysia

Abstract

Cyanobacteria is blue-green microalgae that produces a variety of secondary metabolites such as antibiotic, cytotoxic and antimicrobial agents. Present investigation proposed to study an extraction of active agents from Cyanobacteria and its antibacterial activity. The Cyanobacteria were collected, and isolated colony was found to be Oscillatoria sp. and it was grown in BG 11 medium for mass cultivation. Then the centrifuged biomass was weighed and used for extraction of bioactive compounds. GCMS analysis from Oscillatoria sp. determines fatty acid, triazine derivatives, pyridine derivatives , acridine derivatives. The result revealed that Oscillatoria sp. can play crucial roles as antibacterial agents because the methanolic extract are inhibiting the growth of S. aureus for gram-positive whereas P. aeruginosa for gram-negative bacteria. The crude extract was effective against S. aureus with the highest concentration, 100 mg/ml where area of the zone was 14.10 ± 0.8 mm. The crude extract actively inhibited P. aeruginosa at 75 and 100 mg/ml with highest area of inhibition were in the average of 13.23 ± 0.1 and 15.43 ± 0.2 mm. Finally, the antimicrobial activity was carried out by disc diffusion method with different concentrations of active compounds shows the MIC value in gram-positive bacteria was 30 µg/ml whereas for gram-negative bacteria was 25 µg/ml. Cyanobacteria extract should be preferred and considered to be new natural drug or antibiotics in pharmaceutical and health care industry. This coastal region should be studied further by researchers to study more information and benefits in the future.

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Short Communication
Exploration ofbioactive compounds andantibacterial activity
ofmarine blue‑green microalgae(Oscillatoria sp.) isolatedfromcoastal
region ofwest Malaysia
PrakashBhuyar1,2· MohdHasbiAb.Rahim1· GaantyPragasManiam1· RameshprabuRamaraj2·
NatanamurugarajGovindan1
Received: 9 May 2020 / Accepted: 13 October 2020
© Springer Nature Switzerland AG 2020
Abstract
Cyanobacteria is blue–green microalgae that produces a variety of secondary metabolites such as antibiotic, cytotoxic
and antimicrobial agents. Present investigation proposed to study an extraction of active agents from Cyanobacteria
and its antibacterial activity. The Cyanobacteria were collected, and isolated colony was found to be Oscillatoria sp. and
it was grown in BG 11 medium for mass cultivation. Then the centrifuged biomass was weighed and used for extraction
of bioactive compounds. GCMS analysis from Oscillatoria sp. determines fatty acid, triazine derivatives, pyridine deriva-
tives, acridine derivatives. The result revealed that Oscillatoria sp. can play crucial roles as antibacterial agents because
the methanolic extract are inhibiting the growth of S. aureus for gram-positive whereas P. aeruginosa for gram-negative
bacteria. The crude extract was eective against S. aureus with the highest concentration, 100mg/ml where area of the
zone was 14.10 ± 0.8mm. The crude extract actively inhibited P. aeruginosa at 75 and 100mg/ml with highest area of
inhibition were in the average of 13.23 ± 0.1 and 15.43 ± 0.2mm. Finally, the antimicrobial activity was carried out by disc
diusion method with dierent concentrations of active compounds shows the MIC value in gram-positive bacteria was
30µg/ml whereas for gram-negative bacteria was 25µg/ml. Cyanobacteria extract should be preferred and considered
to be new natural drug or antibiotics in pharmaceutical and health care industry. This coastal region should be studied
further by researchers to study more information and benets in the future.
Keywords Oscillatoria sp.· GCMS· MIC· Pathogen
1 Introduction
Microalgae are the photosynthetic organisms found
in littoral habitats and throughout the ocean waters
known as phytoplankton. Phytoplankton include such
as diatoms (Bacillariophyta), Dinoagellates (Dinophyta),
green, yellow brown flagellates, and cyanobacteria
(blue–green algae) [1–3]. Cyanobacteria is an incredible
old group of prokaryotic organisms that produces a vari-
ety of secondary metabolites such as antibiotic, cytotoxic,
immunosuppressive and enzyme inhibiting agents [4–6].
Bioactive compounds are dened as the secondary metab-
olites that can be isolated and puried from the microal-
gae, plant, microbes and other organisms that has abil-
ity in biological activities [7]. The production of bioactive
compounds from microalgae can be benecial in pharma-
ceutical industry [8, 9]. Algae also contain several bioac-
tive compounds that are benecial as antimicrobial agent
like terpenoids, steroid, phenolic compounds, alkenes and
pholorotannins [10, 11].
* Natanamurugaraj Govindan, natanam@ump.edu.my | 1Algae Biotechnology Laboratory, Faculty ofIndustrial Sciences andTechnology,
Universiti Malaysia Pahang, Lebuhraya Tun Razak, 26300Gambang,Kuantan, Pahang, Malaysia. 2School ofRenewable Energy, Maejo
University, ChiangMai50290, Thailand.

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Microalgae contain variety compounds that can react
to inhibit the microbes like bacteria and function as anti-
bacterial agent. This antibacterial agent can be found in
variety of natural sources like in animal, plant and micro-
algae. Marine algae contribute to the biomass produc-
tion in marine environment and they can also produce
a variety of chemically active metabolite compounds to
protect themselves against other microorganisms in their
surrounding environment [10, 12]. The marine microalgae
are one of the main focuses to new function as the anti-
microbial agents.
In this research, the marine microalgae were cultured
in BG 11 medium. The antibiotics like Streptomycin, Penicil-
lin and Vancomycin were supplemented in culture media
to avoid or reduce the growth of the undesired microbes
that will disturb the growth of the marine microalgae [6,
13, 14]. The aim of the study is to focus on the isolation of
extract form of Oscillatoria sp. that possesses various bio-
logical active compounds which may play crucial roles as
antibacterial agents against various type of gram-positive
(S. aureus and B. subtilis) and gram-negative (P. aeruginosa
and E. coli) pathogenic bacteria. Moreover, the statistical
data was determined by applying one-way ANOVA using
Statistical Program for Social Sciences (SPSS) 16.0 software.
2 Materials andmethods
2.1 Sample collection followed byidentication
The sample collection was done at the Kuantan (3.812601–
103.372003.3°48′45.36″N, 103°22′19.21″E) costal region of
east coast of west Malaysia. The sampling was done in the
month of august in 2019. The marine water samples were
collected with microalgae by plankton net and brought to
laboratory. Serial dilution was carried out to get isolated
colonies. The pH value of the medium was adjusted to pH
7.5 and the temperature was maintained at room tempera-
ture 25°C ± 2°C [15]. The sample was observed and identi-
ed by using uorescent microscope. The morphological
observations and referred to Algae manual it conrmed
that algae belong to blue–green algae group as shown in
Fig.1. The cell diameter is 3.6–4.8µm and the cell length is
1.2–1.8µm. Algae cell trichome aggregation was solitary
with the granulated of cell [16]. According to algae manual
the sample was conrmed that belong to Oscillatoria sp.
2.2 Microalgae mass cultivation
The single colony of cyanobacteria was cultured into 10ml
BG 11 medium. After that, it was transferred into 250ml
medium and adjusted to 500ml for mass culture. Cyano-
bacteria was cultivated in 2-L Erlenmeyer’s ask contained
BG-11 medium and incubated in the racks sourced with
uorescent lamps as a light source. The photo-incubation
was carried out at 30°C and with illuminated at light inten-
sities 12h dark period measured by LI-250 Light meter
[17].
2.3 Culturing ofpathogenic bacteria
The sterile inoculation loop was dipped in the bacterial
suspension and the loopful of suspension streaked over
the surface of the nutrient agar to obtain uniform growth.
A nal sweep was made around the rim of agar. The culture
was grown at 37°C for 18h [15]. The both gram positive
and gram-negative pathogenic bacteria were used for the
study. The gram-negative bacteria used were S. aureus
(CP019117) and B. subtilis (AL009126); and gram-positive
Fig. 1 Species of microalgae cyanobacteria Oscillatoria sp. a uorescent microscopic images and b scanning electron microscope photo-
graph

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bacteria used for the antimicrobial study were E. coli
(U00096) and P. aeruginosa (PAO1).
2.4 Preparation ofcrude extract ofmicroalgae
Algal mass culturing using BG II medium were separated
from centrifugation at 5000rpm for 15min and their pel-
lets were dried at 60°C for 24h. The dry algal mass was
dissolved in methanol (ratio 1:15g/ml) and extracted
throughout 24h [18]. The supernatant was collected after
being centrifuged at 10,000rpm for 10min. The solvent
extracts were concentrated under reduced pressure at
40°C. The dried extracts were resuspended in 3ml of sol-
vent with dierent concentration (50, 75 and 100mg/ml)
and preserved at 4°C till further use in antimicrobial assays
[6, 19].
2.5 Antibacterial activity
The antimicrobial activity was measured and determined
using a well diffusion test [15]. The antibiotic 50µl of
Streptomycin was used in this test as the control. The disks
(6mm) containing 30µg/ml the extract form of the Oscil-
latoria sp. were placed on the surface of agar. The ame
sterile forceps were used to dispense the antibiotic and
extract disk one at a time. The distribution of the disks
should be apart from each other and not close to the
edge of plate. The bacteria inoculum was swabbed and
inoculated on the media plates. The inoculated plates were
then incubated for 24h at 37°C and zone of inhibition was
measured in millimeter (mm) [20].
2.6 Minimum inhibitory concentration (MIC)
The 96 well microtiter plates were swept with ethanol
before used. After that, the rst row of well was pipetted
with 50µl methanol as positive control, second row of well
was pipetted with 50µl of nutrient broth and 50µl bac-
teria culture as negative control. Third row until seventh
rows were lled with dierent concentration of sample in
the range of 10, 15, 20, 25 and 30µg/ml mixed with 50µl
bacteria culture each. After leaving for 24h, the sample
was analyzed with micro plate reader (TECAN, INFINITE
M200PRO). The minimum inhibition concentration value
was determined as the lowest concentration of the extract
in the broth medium that inhibit the visible growth of the
test microorganism [21].
2.7 Gas‑chromatography withmass spectrometer
analysis
The bioactive compounds present in the extracts of
the Oscillatoria sp. which played important roles in the
antimicrobial activity was measured and determined
using the Gas Chromatography-Mass Spectroscopy
[22]. The chromatographic column used HP-5 column
(30m × 0.25mm ID × 0.25µm lm thickness), Agilent Tech-
nologies 7890A (GC system) model. The Chromatographic
conditions were follows: The one micro liter of algae
extract was injected into the GC–MS with Helium carrier
gas and was maintained at a ow rate of 1.50ml/min;
injector and column oven temperature of 280 × and 80°C;
injection mode ‘split’ and split ratio 20:1. Oven tempera-
ture was held isothermal at 80°C for 1min, then increased
to 300°C at a rate of 4°C /min and held isothermal for
5min. MS, (Agilent Technologies 5975C model) conditions
were followed: ion source temperature of 200°C; interface
temperature of 300°C; mass range of 40–1000 mass units
[17, 23]. The individual peaks formed were identied by
comparing their retention time, as well as their mass spec-
tra with the Fienn. Library and NIST 11 (National Institute
of Standard and Technology, Gaithersburg, United States)
library.
2.8 Statistical analysis
The result obtained from the experiment was statistically
analyzed by applying one-way ANOVA with Turkey’s Test
by using SPSS 16.0 (Statistical Program Social Sciences)
software.
3 Results anddiscussion
3.1 Antibacterial activity
Data and results for the zone of inhibition of crude extract
of cyanobacteria against 4 dierent types of bacteria were
illustrated in Table1. The sample of crude extract of Oscil-
latoria sp. was tested with three dierent concentrations
which were 50, 75 and 100mg/ml. The streptomycin was
used as the control for this inhibition. Each reading was
taken as three replicates. The two dierent gram-positive
bacteria (S. aureus and B. subtilis) and 2 type of gram-neg-
ative bacteria (E. coli and P. aeruginosa) had shown slightly
dierent area of inhibition when reacted with dierent
concentration of extract from Oscillatoria sp. The antibac-
terial activity of microalgae was usually assayed using vari-
ous organic solvent for eective extraction of biological
active compounds. The commonly used organic solvent
were methanol, acetone, ether and chloroform–methanol
[24]. Most of all indicated that the methanol extraction
yielded more compared to hexane and ethyl acetate.[7, 25,
26]. Ethyl acetate and methanol were determined as the
most eective organic solvent for the isolation of antibac-
terial compounds [27, 28].

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3.1.1 Zone ofinhibition ofStaphylococcus aureus
Table1 indicated the result for zone of inhibition when
crude extract of Oscillatoria sp. reacted with gram-positive
bacteria S. aureus. The crude extract was eective against
S. aureus with the highest concentration, 100mg/ml where
area of the zone was 14.10 ± 0.8mm. However, for con-
centration 50mg/ml, there was still inhibition, but it was
slightly lower, only in the average of 4.23 ± 0.2mm. The
methanolic extract of microalgae show antibacterial activ-
ity inhibited in the S. aureus with maximum zone of inhi-
bition of 12mm at the concentration of 0. 2mg/ml [29].
The zone of inhibition produced in reaction of methanol
extract of Oscillatoria sp. with 2mg/disk in S. aureus was
27mm [14]. The most sensitive gram-positive bacteria to
the methanolic extract of Oscillatoria sp. was S. aureus with
the zone of inhibition of 13.8 ± 0.8mm [28].
The area for zone of inhibition increases as the concen-
tration of cyanobacteria extract increases. The extract of
Oscillatoria sp. was most eectively in the inhibited growth
of S. aureus with high concentration of 100mg/ml (Fig.2).
3.1.2 Zone ofinhibition ofBacillus subtilis
The zone of inhibition for the reaction of crude extract
of Oscillatoria sp. against B. subtilis was indicated as in
Table1. The crude extract was actively inhibited B. sub-
tilis at 75 and 100mg/ml with the highest area of inhi-
bition, 9.10 ± 0.7mm. Other concentration of 50mg/ml
zone of inhibition was only in average 3.17 ± 0.4mm. The
maximum zone of inhibition of methanol extract of marine
microalgae with 2mg/disk in against B. subtilis was 22mm
[14]. The previous study by [27] proved similar result for
the zone of inhibition of microalgae against B. subtilis.
In Fig.2, shows the area for zone of inhibition of crude
extract of Oscillatoria sp. against B. subtilis which was
active with the concentration 100mg/ml which almost
close to the zone of inhibition produced by Streptomycin
Table 1 Zone of inhibition
of Oscillatoria sp. against S.
aureus, B. subtilis, E. coli, P.
aeruginosa
Microbe Zone of inhibition (mm)
Streptomycin con-
trol (mm) Concentration microalgae extract
50mg/ml 75mg/ml 100mg/ml
Staphylococcus aureus 7.13 ± 0.9 4.23 ± 0.2 10.77 ± 0.7 14.10 ± 0.8
Bacillus subtilis 9.0 ± 0.3 3.17 ± 0.4 8.40 ± 0.5 9.10 ± 0.7
Escherichia coli 11.0 ± 0.2 3.03 ± 0.8 9.26 ± 0.6 10.17 ± 0.4
Pseudomonas aeruginosa 9.0 ± 0.5 7.50 ± 0.1 13.23 ± 0.1 15.43 ± 0.2
Fig. 2 Zone inhibition for
a Staphylococcus aureus b
Escherichia coli c P. aeruginosa
d B. subtilis

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(control). Besides 10 0mg/ml, the concentration of
75mg/ml also produced large zone of inhibition whereas
the 50mg/ml concentration showed the lowest activity
against B. subtilis.
3.1.3 Zone ofinhibition ofEscherichia coli
Based on Table1, it states that the crude extract of Oscil-
latoria sp. was highly responsible in inhibiting E.coli at
the concentration of 100mg/ml with area of inhibition
was 10.17 ± 0.4mm whereas for concentration 50mg/
ml, the area of inhibition was quite low which was only
3.03 ± 0.8mm. The zone of inhibition from this experiment
was similar with the previous study by Salem etal. [28]
who reported the zone of inhibition of E. coli when treated
with methanolic extract of microalgae form area of inhibi-
tion in the range of 8 ± 1–13.3 ± 1.2mm. However, in previ-
ous study of Anandhan etal. [27] it shows that the zone
of inhibition of methanolic extract of microalgae inhib-
ited E. coli was 12mm. The zone of inhibition reported by
Rebecca etal. [30] was 20mm for 100mg/ml and 15mm
for 50mg/ml.
In Fig.2, shows the increasing zone of inhibition against
E. coli as the concentration of Oscillatoria sp. extract
increased. The 75 and 100mg/ml slightly produced the
same area for zone of inhibition and eective inhibited
growth of E. coli whereas the 50mg/ml concentration
proved the lowest antibacterial activity against E. coli.
3.1.4 Zone ofinhibition ofPseudomonas aeruginosa
The zone of inhibition for reaction of crude extract of Oscil-
latoria sp. in against P. aeruginosa was indicated in Table1.
The crude extract actively inhibited P. aeruginosa at 75mg/
ml and 100mg/ml with highest area of inhibition were
in the average of 13.23 ± 0.1mm and 15.43 ± 0.2mm. For
the concentration of 50mg/ml, the area of zone of inhibi-
tion was slightly high in average 7.50 ± 0.1mm. The most
gram-negative bacteria that was sensitive to methanolic
extract of microalgae were P. aeruginosa with the zone of
inhibition was 15 ± 1mm [28]. The zone of inhibition of
methanol extract of microalgae inhibited in P. aeruginosa
obtained from this experiment was similar to the experi-
ment done by Anandhan etal. [27].
Based on Fig.2, the graph shows that the 100mg/
ml was the most active concentration of Oscillatoria sp.
extract that can inhibit growth of P. aeruginosa with larger
zone of inhibition compared to Streptomycin that act as
control. However, concentration at 50mg/ml showed the
lowest zone of inhibition compare to other concentration.
For concentration of 50mg/ml, the crude extract pro-
duced more eciency to inhibit the P. aeruginosa with
area of zone inhibition is 7.50 ± 0.1mm and less eciency
in inhibiting the B. subtilis and E. coli with zone of inhibi-
tion was 3.03 ± 0.8mm respectively as shown in Fig.2. The
crude extract with 75mg/ml concentration was also more
eective against P. aeruginosa and S. aureus with the read-
ing of 13.23 ± 0.1mm and 10.77 ± 0.7mm respectively and
less eective against B. subtilis where the area of inhibition
was 8.40 ± 0.5mm as shown in Fig.2. The crude extract of
Oscillatoria sp. with concentration 100mg/ml showed high
antibacterial activity against the gram-negative bacteria
that was P. aeruginosa which area of zone of inhibition was
15.43 ± 0.2mm as shown in Fig.2 whereas shows less anti-
bacterial activity against the gram-positive bacteria that
was B. subtilis which area of inhibition was 9.10 ± 0.7mm.
The similar study reported by Arnab Pramanik and
Joydeep Mukherjee [6] have revealed the Phormidium
sp. strongly acted as antibacterial agent against the P.
aeruginosa with 14mm zone of inhibition. The LPP group
B showed the effectiveness in inhibiting the S. aureus
(18mm), B. subtilis (15mm) and E. coli (15mm).
The microalgae extract was mostly active in gram neg-
ative bacteria compared to gram positive [28]. Previous
studies indicated that the methanol extraction yielded
more compared to hexane and ethyl acetate [25, 31]. In the
previous report of Rao etal. and Rajasulochana etal. [32],
they revealed similar investigation as in this experiment
where the active compounds in the extract of microalgae
was active against S. aureus for gram-positive bacteria and
P. aeruginosa for gram-negative bacteria. Oscillatoria sp.
proved the antibacterial activity against gram-negative
and gram-positive bacteria [33].
3.2 Minimum inhibitory concentration (MIC)
3.2.1 Gram‑negative bacteria: Pseudomonas aeruginosa
The results from 96-well micro titer plate analyzed by
micro titer plate reader. The positive control is the solvent
namely methanol that was used to extract the bioactive
compound from the crude extract of the Oscillatoria sp.
The negative control used was the culture of selected
bacteria with the nutrient broth. The dierent concentra-
tions of Oscillatoria sp. extract were prepared from 10, 15,
20, 25 and 30µg/ml (Fig.3). From the data, the reading
is slightly in ascending form of the inhibition level that
occurred in the micro plate between reactions of Oscil-
latoria sp. extract against the bacteria culture. The pattern
of inhibition level formed can be seen more clearly from
the graphical data.
Figure3 shows the level of inhibition produced from
the reaction of crude extract from Oscillatoria sp. against
the bacteria Pseudomonas aeruginosa. From the graph, it
shows the increasing level of inhibition. The most mini-
mal concentration that can cause this inhibition to occur

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eectively is 25µg/ml with the optimal density is 0.9391.
The Oscillatoria sp. extract depends on 25µg/ml to con-
trol the growth of gram-negative bacteria P. aeruginosa
because the active compounds which function to inhibit
growth of bacteria was active in this concentration.
Besides that, the graph also shows that the inhibition
level for each concentration started to increase at the con-
centration 5µg/ml. So, it shows that at the concentration
of 25µg/ml the antibacterial activity of crude extract from
Oscillatoria sp. against the gram-negative bacteria, P. aer-
uginosa is higher. The MIC result obtained from this experi-
ment was almost the same as the previous study by [28]
Salem etal. where the MIC for P. aeruginosa was 20µg/ml.
3.2.2 Gram‑positive bacteria: Staphylococcus aureus
Figure4 indicates the data analyzed by the micro titer
plate reader from the reaction of the gram-positive bac-
teria that is S. aureus with dierent concentration of crude
extract of Oscillatoria sp. The dierent concentration pre-
pared were 10, 15, 20, 25 and 30µg/ml.
The solvent methanol was used as the positive con-
trol whereas the selected bacteria culture within nutrient
broth was served as negative control. The reading of level
of inhibition produce was ascending for each concentra-
tion. The graphical data may present clear pattern pro-
duced from that reaction.
Figure4 above presents the increasing reading pattern
for the level of inhibition produced from the reaction of
crude extract of Oscillatoria sp. in inhibiting the gram-
positive bacteria S. aureus. The dierent concentration of
crude extract from Oscillatoria sp. studied in this experi-
ment were 10, 15, 20, 25 and 30µg/ml. Hence, from the
graph above the minimal concentration that may inhibit
the reaction of bacteria was 30µg/ml with the level of
optimum density was 0.4764. It proved that at concen-
tration of 30µg/ml, the crude extract of Oscillatoria sp.
can function as antibacterial agent eciently against the
gram-positive bacteria S. aureus. The minimal inhibitory
concentration (MIC) for microalgae against S. aureus was
25µg/ml because the di-phenolic metabolites like bromo-
phenols were found to be the most eective compound
as antimicrobial agents [34, 35].
The minimum inhibitory concentration (MIC) of marine
algae against S. aureus was 0.5mg/ml and maximum MIC
was 1mg/ml. (Selim, 2012). The MIC for S. aureus obtained
in this experiment was almost the same as the previous
study of Salem etal. (2011) which was in the range of
20–50µg/ml.
3.3 Statistical analysis
Figure5 shows the antibacterial activity of Oscillatoria sp.
extract with dierent concentrations (50, 75 and 100mg/
ml) in 2 dierent types of gram-positive bacteria (S. aureus
and B. subtilis) and 2 dierent types of gram-negative bac-
teria (E. coli and P. aeruginosa). Therefore, the antibiotic
Streptomycin was served as control. The result showed a
signicantly higher antibacterial activity (p < 0.05) which
was determined by a one-way ANOVA and the error bars
were by SEM, n = 3.
Fig. 3 Graph of level of inhibition (OD) against concentration of sample for minimal inhibitory concentration (MIC) for P. aeruginosa

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3.4 Bioactive compounds analysis ofcyanobacteria
extract
The bioactive compound identified in cyanobacteria
were fatty acid, amino acid derivative, indolizine deriva-
tive, ether derivative, cinchoninic acid, phenol, pyridine
derivative, benzyl alcohol derivative and triazine derivative
as shown in Fig.6 and Table2. Halogenated compounds
present in microalgae and macroalgae were indicated
as biological active compounds [36, 37]. The important
compounds that were indicated as antimicrobial are fatty
acid, acrylic acid, terpenes, phenol and halogenated com-
pounds [29]. Previous study by Kolanjinathan etal. [20]
found the most bioactive compounds that present in
microalgae extract was chemically classied as aromatics,
sulphate polysaccharide, brominated, nitrogen-heterocy-
clic, protein, peptides, dibutanoids, nitrosulphuric-heter-
ocyclic and sterols. The Oscillatoria sp. was active against
pathogenic bacteria with the presence of pyridine and
n-butanol [33].
Fig. 4 Graph of level of inhibition (OD) against concentration of sample for minimal inhibitory concentration (MIC) for against S. aureus
Fig. 5 Antibacterial activity
of Oscillatoria sp. extract with
dierent concentrations (50, 75
and 100mg/ml)

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The 1, 3, 5-triazine was the bioactive compound identi-
ed at retention time of 26.544min. Triazine was included
in chemical species of heterocyclic aromatic ring com-
pound where the three nitrogens replaced the carbon-
hydrogen units on the benzene ring. 1, 3, 5-triazine repre-
sent incredible class of compound with wide spectrum of
biological activities such as antimicrobial, anticancer, anti-
viral and fungicidal [38, 39]. The earlier report by Sarmah
and Patel [40] also had reported that the triazine deriva-
tives have potential against gram-positive bacteria such as
B. subtilis and S. aureus and gram-negative bacteria such
as P. aeruginosa and E. coli.
Fig. 6 Total ionic chromatogram biological active compound of methanol extract of Oscillatoria sp. with HP-5 column (30m × 0.25mm) with
helium as carrier gas
Table 2 Total ionic chromatogram biological active compound of methanol extract of Oscillatoria sp. with HP-5 column (30 × 0.25mm) with
helium as carrier gas
Compounds name Compound nature Molecular formula Retention
time (min)
4,6-bis(diethylamino)-1,3,5-triazine Triazine derivative C3H3N326.544
5-Nitro-3-cyano-2(1H)-pyridone Pyridone derivative C5H4NH(O) 32.401
Triphenylphosphine oxide Phenyl derivative C18H15OP 40.946
1,4 benzenedicarboxamide Phathalic acid derivative C6H4(COOH)247.525
Benzenemethanol Benzyl alcohol derivative C7H8O 49.460
trimethylsilyl ether Ether derivative C5H12OSi 49.927
2-Methyl-7-phenyl indole Indole derivative C8H7N 57.984
Acetic acid Fatty acid C2H4O258.026
Silicic acid Carboxylic acid Si (OH)458.292
9-Oxo-9,10-dihydro acridine-4-yl Acridine derivative C13H9N 59.823
2-(p-Fluorophenyl)-6-methylcinchoninic acid Cinchoninic acid C10H7NO260.003
5-Methyl-2-phenyl indolizine Indolizine derivative C15H13N 60.832

Vol.:(0123456789)
SN Applied Sciences (2020) 2:1906 | https://doi.org/10.1007/s42452-020-03698-8 Short Communication
4 Conclusion
The result obtained from this experiment clearly revealed
that Oscillatoria sp. can play crucial roles as antibacterial
agents because the extract from Oscillatoria sp. showed
impressive result for zone of inhibition area against gram-
positive bacteria (S. aureus and B. subtilis) and gram-
negative bacteria (E. coli and P. aeruginosa). However, the
methanolic extract of Oscillatoria sp. from this experiment
proved to be more actively in inhibiting the growth of S.
aureus for gram-positive whereas P. aeruginosa for gram-
negative bacteria. The antibacterial activity from the same
extract of Oscillatoria sp. are for several bioactive com-
pounds which has also been reported in many studies
such as fatty acid, triazine derivatives, pyridine derivatives,
acridine derivatives and etc. which had proven to be very
eective in playing their role as antibacterial. The mini-
mal inhibitory concentration (MIC) value in gram-positive
bacteria was 30µg/ml whereas for gram-negative bacteria
was 25µg/ml. Oscillatoria sp. extract depends on those
concentrations to control the growth of bacteria because
of the bioactive compounds which function as antibacte-
rial agent active and high amount in those concentrations.
Based on the experiment, marine cyanobacteria (Oscil-
latoria sp.) have proven their potential as antimicrobial,
anticancer, antioxidant and antitumor activity. The extract
from cyanobacteria can be applied for various treatment
for several diseases instead of using chemical drugs or
treatments. Cyanobacteria extract should be preferred
and considered to be new natural drug or antibiotics in
pharmaceutical and health care industry. The authorities
and responsibility should come out with new alternative
in culturing microalgae in large scale for commercializa-
tion and improvement of the health care industry without
side eects.
Acknowledgements The authors gratefully acknowledged Univer-
siti Malaysia Pahang for the nancial assistance through the Internal
Research Grant No. RDU1903125 and Flagship Grant No. RDU182205.
Author (Prakash Bhuyar) is thankful to UMP for providing Doctoral
Research Scholarship DRS as a nancial support.
Compliance with ethical standards
Conflict of interest There are no conicts to declare.
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