The Potential of Proteolytic Bacteria Isolated from Peat Soil against

Salmonella Typhi and Escherichia Coli

Rizni Syahputri

, Rachmiati

, Sartini

and Kiki Nurtjahja

Department of Biology, Universitas Medan Area, Medan, Indonesia

Department of Biology, Universitas Sumatera Utara, Medan, Indonesia

Keywords: Proteolytic bacteria, Peat soil, Salmonella typhi, Escherichia coli

Abstract: Peat soil consisted of organic organic soil that developed of plant residue in wet condition. The aim of this

study was to investigate the ability of protelytic bacteria originated from peat soil in inhibiting pathogenic

bacteria (Salmonella typhi and Escherichia coli). The soil samples were obtained from an area ±200 m

Labuhan Batu, North Sumatera, Indonesia. Each soil samples (200 g) were homogenized and serial dilution

was conducted to isolate soil bacteria. All of the bacteria then were cultured in skim milk agar at 37°C for 48

h. Bacterial colony with clear zone were isolated and identified. Nutrient agar plate medium was used to

examine antagonist characteristics between pathogenic and proteolytic bacteria. Results showed that total 12

isolates bacteria were succesfully isolated. Among 12 isokates, six isolates (PSp7, PSp8, PSp9, PSp10, PSp11

dan PSp12) were proteolytic characteristics. Among the proteolytic isolates, PSp7b and PSp11 were the

highest clear zone. However, antagonism of isolate PSp10 (14.88 mm) againts E. coli was higher than that of

PSp9 (10.25 mm) againts S. typhi.

1 INTRODUCTION

As a tropical country and high rainfall, Indonesia has

high proportion of peat soil (Warren et al. (2017). The

distribution of peat soil in Indonesia were in Sumatera

(35%), Kalimantan (30%), Papua (30%) and

Sulawesi (3%) (Wahyumto et al. (2006). Mahdiyah

(2015) reported that peat soil contain microorganisms

and potential for health and agriculture development.

The presence of cellulolytic and proteolytic

microorganisms in peat soil is crucial in degrading

high organic compound. Peat soil bacteria is potential

source of antibiotic (Yuliar et al. (2011), Enzyme

production (Ravi et al. 2015). Mahdiyah (2015) was

reported the presence of proteolytic bacteria isolated

from peat swamp soil in Banjarmasin, South

Kalimantan. Afriyani et al. (2009) reported that

Lactobacillus brevis was proteolytic that potential to

inhibit Staphylococcus aureus. Whereas, Erlindawati

et al. (2015) was successful to isolate three isolates

peatsoil bacteria that inhibit Escherichia coli,

Enterobacter cloacae, Enterobacter gergoviae, and

Proteus rettgeri.

The importance peat soil that support ecosystem

can prevent damage by human activities (Warren et

al. (2017). High biodiversity of microorganism

pacticularly bacteria that potential for human life

required to be explored. The aim of recent study was

to isolate proteolytic bacteria from peat soil that

potential in inhibiting pathogenic bacteria Salmonella

typhi and Escherichia coli.

2 MATERIALS AND METHOD

2.1 Sampling of Peat Soil

The research was conducted from August to

Nopember 2020 at Microbiology Laboratory, Faculty

of Mathematics and Natural Sciences, Universitas

Negeri Medan. As much as 200 g from five sites of

peat soil as samples were obtained from sampling

area 200 m

at Labuhan batu, North Sumatera. Three

replicates for each site. All soil samples then were

packed in steril polyethylene bag.

2.2 Screening and Isolation of

Proteolytic Bacteria

Each soil sample was homogenized and 25 g of the

homogenized sample in 500 ml flask was mixed in

Syahputri, R., Rachmiati, ., Sartini, . and Nurtjahja, K.

The Potential of Proteolitic Bacteria Isolated from Peat Soil against Salmonella typhi and Escherichia coli.

DOI: 10.5220/0010612900002775

In Proceedings of the 1st International MIPAnet Conference on Science and Mathematics (IMC-SciMath 2019), pages 545-547

ISBN: 978-989-758-556-2

545

250 ml sterilized distilled water. The suspension was

shaken and 1 ml of the aliquot was poured with skim

milk agar on to petri dish (9 cm in diameter). Four

dilution was made (10

-1

, 10

-2

, 10

-3

, 10

-4

) for each

sample with three replicates. All plates were

incubated for 24 h at 37°C. Separate bacterial

colonies with clear zone were enumerated and

isolated in nutriet agar slant.

2.3 Examination of Proteolytic

Bacteria

Each isolate of proteolytic bacteria was examined in

skim milk plate agar. Each culture was incubated for

24 h at 37°C. The presence of clear zone surrounding

the colonies was determined.

2.4 Antimicrobial Activity of

Proteolytic Bacteria

Pathogenic bacteria, Escherichia coli and Salmonella

typhi used were culture collection of Laboratory

Microbiology, Pharmacy Department, Universitas

Sumatera Utara. Subculture each of the bacteria was

tested againts isolates of proteolytic bacteria using

Kirby-Bauer method in petri dish (9 cm in diameter).

Each suspension of the bacteria was spread out at

nutrient agar plate medium and paper disc containing

0.1 ml proteolytic bacteria was put on the plate. All

plates were incubated at 24 h for 37°C. Three

replicates for each culture. The presence of clear zone

surrouding paper disc was observed.

3 RESULTS AND DISCUSSION

3.1 Proteolytic Bacteria in Peat Soil

A total of 12 bacterial isolates (Psp1, PSp2, PSp3,

PSp4, PSp5, PSp6, PSp7, PSp8, PSp9, PSp10, PSp11,

PSp12) of proteolytic bacteria were successfully

isolated from peat soil. However, only 6 isolates

(PSp7, PSp8, PSp9, PSp10, PSp11, PSp12) were

proteolytic characteristics that indicated by the

presence of clear zone surrounding their colonies in

skim milk agar medium. The characteristic each of

the isolates was indicated by clear zone (Table 1).

Table 1: Isolates of proteolytic bacteria isolated from

peatland in skim milk agar medium after incubation 24 hour

at 37°C

Isolates of proteolytic

bacteria

Diameter of clear zone

(mm) in skim milk agar

PSp7 9.0

PSp8 8.5

PSp9 8.0

PSp10 8.5

PSp11 10.0

PSp12 8.5

As shown in Table 1 each isolate has different

proteolytic activity as indicated by different diameter

clear zone. However, isolates such as PSp11 and

PSp7 were the highest diameter 9.0 mm and 10.0 mm

respectively. Based morphological characteristic all

isolates has gram positive, streptococci except PSp11

has bacil form. Our results were in line with

Mahdiyah (2015) that most bacteria isolated from

peat soil with streptococci and gram negative.

Hidayat (2004) reported most bacteria isolates from

peat soil at Tanjung Puting, Kalimantan was genus of

Bacillus that rod shape and proteolytic activity.

Whereas, isolation of proteolytic bacteria from soil by

Ravi et al. (2015) stated most of the species was

Bacillus subtilis.

3.2 Antibacterial Activity of Proteolytic

Bacteria against Pathogenic

Bacteria

The potential of antibaccterial isolated from peatland

againts Salmonella typhi and Escherichia coli was

incated by the presence of clear zone Table 2.

Table 2: Antagonistic activity of proteolytic bacteria

Bacterial

isolates

Pathogenic bacteria/ Diameter of

inhibition (mm)

Salmonella typhi Escherichia coli

PSp7 0,00 12.45

PSp8 8.50 10.37

PSp9 10.25 10.10

PSp10 9.35 14.88

PSp11 0.00 10.50

PSp12 8.67 10.50

Table 2 showed that all proteolytic bacteria inhibit

both Salmonella typhi and Escherichia coli as

indicated by inhibition zone. The potential inhibition

of all isolates on E. coli is higher than that of S. typhi.

Even, two strain PSp7 and PSp11 both are proteolytic

and have no inhibition on S. typhi. However each

strain showed different inhibition, strain PSp9

IMC-SciMath 2019 - The International MIPAnet Conference on Science and Mathematics (IMC-SciMath)

546

showed the inhibition (10.25 mm) on S. typhi,

whereas, strain PSp10 on E. coli (14.88 mm). The

inhibition might occur the proteolytic have hydrolytic

compounds. Erlindawati (2015) and Agustono et al.

(2021) reported that peat soil bacteria produce

protease and anti-microbe. In our results indicate that

all isolate proteolytic bacteria were gram positive and

showed antibacterial activity as previously reported

by Ong et al. (2015).

4 CONCLUSION

Different strains of proteolytic bacteria isolated from

peat soil have antagonis activity againts Salmonella

typhi and Escherichia coli.

REFERENCES

Agustono, Suprapto, H., Muhajir. 2012, Strategi bakteri

probiotik untuk menekan pertumbuhan bakteri patogen

di dalam pencernaan kerapu Chromileptes altivelis

dengan memproduksi beberapa bakteri substansi,

Jurnal Ilmiah Perikanan dan Kelautan, vol. 4, no. 2, hal.

199-205

Erlindawati, Puji A., Afghani J. 2015. Identifikasi dan uji

aktivitas antibakteri dari tiga isolat bakteri tanah

gambut Kalimantan Barat. JKK, 4(1):13-17

Hidayat, I. 2004. Characteristics of the peat soil Bacillus sp.

Berk. Penelitian Hayati 10: 31-35.

Mahdiyah, D. 2015. Isolasi bakteri dari tanah gambut

penghasil enzim protease. Jurnal Pharmascience, 2( 2):

71-79.

Ong, K.S., Yule C.M., Lee S.M. 2015. Antimicrobial

producing bacteria isolated from tropical peat swamp

soil. Malaysian Journal of Microbiology 11(2): 170-

175.

Ravi, M., Rayudu K., Gaddad V.K.S.M., Jayaraj Y.M.

2015. Studies on the potent protease producing bacteria

from soil samples. International Journal of Current

Microbiology and Applied Sciences. 4:983-988.

Wahyunto, B. Heryanto, Hasyim Bekti dan Fitri Widiastuti.

2006. Sebaran gambut dan cadangan karbon bawah

permukaan di Papua, 2000-2001. Wetlands

International – Indonesia Programmed an Wildlife

Habitat Canada. Bogor. Indonesia.

Warren, W., Hergoualch, Kauffman J.B., Murdiyarso D.,

Kolka R. 2017. Ann appraissal of Indonesia’s immense

peat carbon stockusing national peatland maps:

uncertainties and potential lossesfrom conversion.

Carbon Balance and Management 12 (12): 1-12.

Yuliar, Abidin Z., Mangunwardoyo W. 2011. Potency of

biocontrol agents isolated from compost and peat soil

of tropical peat swamp forest in Kalampangan zone,

Central Kalimantan. Journal of Forestry Research 8(2):

144-157.

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