Volume 05 Issue 03-2025
1
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
05
ISSUE
03
Pages:
1-8
OCLC
–
1368736135
A
BSTRACT
The emergence of antibiotic resistance in aquatic ecosystems, especially in fish, poses significant public
health risks, especially when these bacteria are transferred to humans through the food chain. This study
aimed to investigate antibiotic resistance patterns of bacteria isolated from the gut of fish and assess the
antibacterial potential of Lactic Acid Bacteria (LAB) against multiple drug-resistant (MDR) strains. A total
of 100 fish samples from various aquatic environments were analyzed, and the presence of antibiotic-
resistant bacteria was identified. Lactic acid bacteria, primarily Lactobacillus spp., were isolated from
fermented food products and tested for antibacterial activity. Results showed a high prevalence of MDR
bacteria in the fish gut. Furthermore, LAB exhibited promising antibacterial activity against these resistant
strains, suggesting their potential as natural alternatives to antibiotics in controlling fish-associated
pathogens.
K
EYWORDS
Antibiotic Resistance, Fish Gut Microbiota, Multidrug-Resistant Bacteria, Lactic Acid Bacteria (LAB),
Aquaculture, Antibacterial Activity, Probiotics in Aquaculture, Aquatic Pathogens, Antibiotic Alternatives,
Microbial Resistance, Aquatic Ecosystems, Fish Farming, Lactic Acid Production, Antimicrobial Peptides,
Research Article
Antibiotic Resistance in Fish Gut Microbiota and the
Antibacterial Potential of Lactic Acid Bacteria Against
Multidrug-Resistant Isolates
Submission Date:
January 03,
2025,
Accepted Date:
February 02, 2025,
Published Date:
March 01, 2025
Ravi Kumar
Jawaharlal Nehru Centre For Advanced Scientific Research, Bengaluru, Karnataka, India
Priya Nair
Jawaharlal Nehru Centre For Advanced Scientific Research, Bengaluru, Karnataka, India
Journal
Website:
http://sciencebring.co
m/index.php/ijasr
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Volume 05 Issue 03-2025
2
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
05
ISSUE
03
Pages:
1-8
OCLC
–
1368736135
Sustainable Aquaculture, Fish Health Management, Antibiotic Use in Aquaculture, Fish Disease Control,
Bacteriocins, Gut Microbiota Modulation.
I
NTRODUCTION
The increasing reliance on antibiotics in
aquaculture has contributed to the rise of
antibiotic-resistant
bacteria
in
aquatic
ecosystems, including fish guts. These resistant
bacteria not only pose a threat to fish health but
can also have serious implications for human
health when transmitted through seafood. The
development of novel antimicrobial strategies is
critical in combating this growing problem. Lactic
Acid Bacteria (LAB), which are generally
considered beneficial microorganisms in food
fermentation, have been shown to possess
antimicrobial properties against a variety of
pathogens. This study focuses on investigating
the antibiotic resistance patterns of bacteria
isolated from the gut of fish and evaluating the
antibacterial potential of LAB against multiple
drug-resistant (MDR) strains.
M
ETHODS
Sample Collection
A total of 100 fish samples were collected from
different aquatic environments, including
freshwater and marine water sources. Fish were
obtained from local markets and fish farms. The
samples were kept under sterile conditions and
transported to the laboratory for analysis.
Isolation and Identification of Bacteria
Fish guts were aseptically removed and
homogenized, and serial dilutions were plated on
selective media for the isolation of bacterial
colonies. Bacterial isolates were cultured on
MacConkey agar and Nutrient agar, followed by
Gram
staining,
biochemical
tests,
and
identification using molecular methods such as
16S rRNA sequencing.
Antibiotic Susceptibility Testing
Antibiotic susceptibility was determined using
the disk diffusion method, following the
guidelines set by the Clinical and Laboratory
Standards Institute (CLSI). A panel of 10
commonly used antibiotics was tested, including
ampicillin, tetracycline, ciprofloxacin, and
streptomycin. The resistant strains were
classified as multidrug-resistant (MDR) if they
exhibited resistance to at least three different
antibiotic classes.
Isolation of Lactic Acid Bacteria
LAB were isolated from fermented food products
such as yogurt and pickles using MRS agar (de
Man, Rogosa, and Sharpe agar) and incubated at
37°C for 48 hours. Identification of LAB was
confirmed by morphological, biochemical, and
molecular methods, including 16S rRNA
sequencing.
Antibacterial Activity of LAB
Volume 05 Issue 03-2025
3
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
05
ISSUE
03
Pages:
1-8
OCLC
–
1368736135
The antibacterial activity of LAB against MDR
bacteria was evaluated by the agar well diffusion
method. LAB isolates were cultured and
centrifuged, and the supernatant was collected.
The supernatants were added to wells in agar
plates inoculated with MDR bacterial strains. The
presence of a clear zone of inhibition around the
wells was measured after incubation, indicating
antibacterial activity.
R
ESULTS
Prevalence of Antibiotic-Resistant Bacteria in
Fish Gut
Out of the 100 fish samples, 85% yielded bacterial
growth, and 70% of the isolates were identified as
Gram-negative bacteria. The most commonly
isolated bacterial genera were Escherichia,
Salmonella, and Pseudomonas. Among these,
60% were found to be multidrug-resistant. The
most common resistances observed were against
ampicillin, tetracycline, and chloramphenicol.
Antibacterial Potential of LAB
Among the 20 LAB isolates obtained, 15 showed
antibacterial activity against MDR bacterial
strains. The most effective LAB species were
Lactobacillus acidophilus and Lactobacillus
rhamnosus, which exhibited significant inhibition
zones ranging from 12 to 20 mm. The
antimicrobial activity was attributed to the
production of organic acids (lactic acid) and other
antimicrobial peptides.
Correlation Between Antibiotic Resistance and
Fish Gut Microbiota
There was a significant correlation between the
presence of antibiotic-resistant bacteria and the
fish gut microbiota. Fish sourced from
aquaculture
environments
with
frequent
antibiotic use had a higher prevalence of MDR
bacteria. This suggests that the aquaculture
environment may serve as a reservoir for
resistant pathogens, which could potentially
transfer to humans.
D
ISCUSSION
The rise of antibiotic resistance in aquatic
environments is a critical issue for both
environmental health and human safety,
especially as resistant bacteria in fish guts can
potentially enter the human food chain through
seafood consumption. This study found a
significant prevalence of multidrug-resistant
(MDR) bacteria in the gut microbiota of fish,
which supports the growing concern of the
misuse of antibiotics in aquaculture.
Antibiotic Resistance in Fish Gut Bacteria
The high rate of antibiotic resistance observed in
this study, where 60% of bacterial isolates from
fish were MDR, highlights the extensive presence
of resistance in fish populations. The most
commonly observed resistances were to widely
used antibiotics like ampicillin, tetracycline, and
chloramphenicol, which are frequently employed
in aquaculture to prevent or treat bacterial
infections in fish. These antibiotics, while
beneficial for controlling disease outbreaks in
farms, also contribute to the selection of resistant
strains within the fish microbiota.
Volume 05 Issue 03-2025
4
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
05
ISSUE
03
Pages:
1-8
OCLC
–
1368736135
In particular, the high prevalence of Escherichia
coli, Salmonella, and Pseudomonas in the fish gut
is noteworthy. These are common bacterial
genera found in both the aquatic environment
and human gut, and their resistance to multiple
antibiotics raises significant concerns. Not only
do these bacteria pose a risk to fish health, but
they also represent a potential public health
threat if they are transferred to humans through
contaminated seafood.
Additionally, the findings indicate that fish
sourced
from
aquaculture
environments,
especially those with frequent antibiotic use,
harbored a higher prevalence of MDR bacteria
compared to those from wild or less intensively
farmed environments. This correlation suggests
that intensive aquaculture, where antibiotics are
routinely used, may exacerbate the selection
pressure for antibiotic-resistant strains. The
closed environments and high-density conditions
of many fish farms provide a perfect breeding
ground for resistant bacteria, leading to the
persistence and propagation of resistance genes
within these systems.
Role of Lactic Acid Bacteria (LAB) in Controlling
MDR Strains
The antibacterial potential of LAB observed in
this study is promising and suggests that these
microorganisms could serve as a viable
alternative to antibiotics in controlling MDR
pathogens in aquaculture systems. LAB,
particularly Lactobacillus acidophilus and
Lactobacillus rhamnosus, exhibited significant
inhibitory effects against MDR strains of bacteria
isolated from the fish gut. This antibacterial
activity is likely due to the production of organic
acids, such as lactic acid, which lowers the pH of
the environment and inhibits bacterial growth.
Additionally, LAB can produce antimicrobial
peptides (such as bacteriocins) that target and kill
pathogenic bacteria.
The antimicrobial properties of LAB have been
well documented in human and animal health,
especially in the context of gut health and
infection prevention. In aquaculture, LAB could
be used as probiotics to enhance fish immunity
and suppress harmful bacteria in the gut. LAB
could potentially replace or reduce the need for
antibiotics, thus reducing the risk of further
developing antibiotic resistance in aquatic
systems.
Furthermore, the use of LAB in aquaculture could
improve the overall health and growth of fish by
promoting a balanced and diverse gut microbiota.
By
introducing
beneficial
bacteria,
the
competition for resources between harmful and
helpful bacteria can be enhanced, potentially
reducing the colonization of pathogens in the gut
and preventing infections.
Environmental and Public Health Implications
The issue of antibiotic resistance in aquatic
environments has significant implications for
both environmental and public health. The
development and spread of resistant bacteria in
fish guts is a direct result of the overuse and
misuse of antibiotics in aquaculture. Given that
antibiotic-resistant bacteria can transfer from
fish to humans through the consumption of
Volume 05 Issue 03-2025
5
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
05
ISSUE
03
Pages:
1-8
OCLC
–
1368736135
contaminated seafood, it is crucial to address this
issue not only for the health of aquatic organisms
but also for the safety of the global food supply.
The findings in this study underline the necessity
of adopting alternative strategies to reduce the
reliance on antibiotics in aquaculture. Probiotics,
such as LAB, may offer a safer and more
sustainable solution, reducing the risk of
resistance development while promoting healthy
fish farming practices. By using LAB in
aquaculture, it may also be possible to enhance
the microbial diversity of the fish gut, which could
improve overall fish health and resilience to
infections.
Moreover, as the world’s population continues to
grow and the demand for seafood increases,
sustainable and safe practices in aquaculture are
imperative. The use of LAB as a natural biocontrol
agent could help mitigate the risks associated
with antibiotic resistance while also reducing the
environmental footprint of antibiotic use in
aquaculture.
Challenges and Future Research
Despite the promising results, several challenges
remain for the broader application of LAB in
aquaculture. One of the key challenges is the
variability in the efficacy of LAB across different
fish species, water conditions, and farming
practices. Future studies should focus on
evaluating the strain-specific effects of LAB and
determining the most effective dosages and
delivery methods for aquaculture applications.
Another challenge is the need for regulatory
frameworks that ensure the safe use of LAB in
aquaculture. While LAB are generally recognized
as safe (GRAS) for use in food and agriculture, the
long-term effects of LAB supplementation in
aquaculture
need
further
investigation.
Additionally, potential interactions between LAB
and other microorganisms in the fish gut should
be studied to assess any unintended
consequences on gut health and fish physiology.
Finally, more research is needed to explore the
mechanisms
behind
LAB’s
antimicro
bial
properties, including the identification of specific
antimicrobial peptides and their potential to
target specific pathogens. Understanding the
molecular mechanisms will be essential for
optimizing LAB-based treatments and ensuring
their effectiveness in combating MDR bacteria.
The growing issue of antibiotic resistance in fish
microbiota, particularly in aquaculture systems,
is a pressing concern that needs immediate
attention. This study highlights the prevalence of
multidrug-resistant bacteria in fish guts and
demonstrates the potential of Lactic Acid Bacteria
as a natural alternative to antibiotics in
controlling these pathogens. LAB's antibacterial
properties offer a promising approach for
reducing antibiotic reliance in aquaculture and
mitigating the spread of resistant bacteria. As
such, LAB could play a crucial role in the
development of sustainable aquaculture practices
that promote both fish health and food safety.
Further research into optimizing the use of LAB in
aquaculture and understanding the long-term
Volume 05 Issue 03-2025
6
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
05
ISSUE
03
Pages:
1-8
OCLC
–
1368736135
effects of their application is necessary to ensure
the success of this approach.
The study demonstrated a high prevalence of
antibiotic-resistant bacteria in the fish gut,
highlighting the need for better management
practices in aquaculture. The isolation of multiple
drug-resistant strains from fish suggests that the
use of antibiotics in fish farming contributes to
the dissemination of resistance genes within
aquatic environments. The findings also
emphasize the potential of LAB as a natural, safe
alternative to synthetic antibiotics in controlling
pathogenic bacteria in aquaculture. LAB's
antimicrobial activity against MDR bacteria is
promising and supports their application in
probiotics or as part of an integrated disease
management strategy in aquaculture.
C
ONCLUSION
The findings of this study underscore the growing
challenge of antibiotic resistance in aquaculture,
particularly in the gut microbiota of fish, which
can pose a significant risk to both aquatic health
and public safety. The high prevalence of
multidrug-resistant (MDR) bacteria found in the
gut microbiota of fish is a direct consequence of
the widespread and often indiscriminate use of
antibiotics in aquaculture. This issue not only
threatens the sustainability of fish farming but
also highlights a potential pathway for the
transfer of antibiotic-resistant pathogens to
humans through the consumption of seafood.
This study also demonstrated the promising
potential of Lactic Acid Bacteria (LAB) as a
natural
and
sustainable
alternative
to
conventional antibiotics in combating antibiotic-
resistant pathogens in aquaculture. LAB,
particularly Lactobacillus acidophilus and
Lactobacillus rhamnosus, exhibited significant
antibacterial activity against the MDR strains
isolated from fish, offering hope for the
development of safer aquaculture practices.
LAB's antimicrobial properties, which include the
production of lactic acid and antimicrobial
peptides, can help mitigate the risk of antibiotic
resistance while promoting a healthier fish gut
microbiota. This approach may lead to reduced
dependence
on
antibiotics,
lower
the
environmental impact of antibiotic use in
aquaculture, and reduce the risk of resistant
bacteria entering the human food chain.
Importantly, the results of this study emphasize
the need for a shift in the way antibiotics are used
in aquaculture. The overuse and misuse of
antibiotics in fish farming systems create
environments that select for resistant bacteria,
which, if left unaddressed, can contribute to the
global issue of antimicrobial resistance.
Therefore, adopting alternative strategies like
LAB-based probiotics presents an opportunity to
improve the health and sustainability of
aquaculture systems while maintaining the safety
of seafood products.
Furthermore, the positive effects of LAB in
enhancing fish health and immunity should be
considered as part of an integrated disease
management strategy. LAB supplementation
could reduce the occurrence of pathogenic
infections in fish, improve fish welfare, and
Volume 05 Issue 03-2025
7
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
05
ISSUE
03
Pages:
1-8
OCLC
–
1368736135
increase
overall
farm
productivity.
By
incorporating LAB into regular aquaculture
practices, the aquaculture industry can help curb
the development of resistance without
compromising the health of aquatic ecosystems.
Despite the promising potential of LAB,
challenges remain in optimizing their use in real-
world aquaculture settings. More research is
needed to determine the most effective LAB
strains, their optimal dosages, and the best
methods of administration in different
aquaculture
environments.
Furthermore,
understanding the interaction between LAB and
other microorganisms in the fish gut, as well as
any long-term effects of LAB supplementation,
will be crucial in determining the broader
applicability of this approach.
In conclusion, this study highlights the urgent
need for innovative solutions to combat antibiotic
resistance in aquaculture and the role that LAB
can play in addressing this issue. With the
growing global demand for sustainable and safe
seafood, integrating LAB into aquaculture
systems presents a promising and natural
alternative to antibiotic use. Continued research
into LAB’s efficacy and safety, coupled with more
sustainable antibiotic practices, will be essential
in ensuring the future health of both aquatic
organisms and the consumers who rely on them.
Ultimately, adopting probiotic-based approaches
could significantly contribute to the reduction of
antibiotic resistance, ensuring the long-term
sustainability of the aquaculture industry and the
safety of seafood for human consumption.
This study highlights the growing concern of
antibiotic resistance in fish gut microbiota and
underscores the potential of Lactic Acid Bacteria
as a natural antibacterial agent against multidrug-
resistant pathogens. The use of LAB in
aquaculture could offer a viable solution to
reduce the reliance on antibiotics, enhancing both
fish health and food safety. Further research is
necessary to explore the underlying mechanisms
of LAB's antimicrobial activity and to develop
practical
applications
in
aquaculture
management.
R
EFERENCES
1.
Binh, C.T.T., Tran, L., & Minh, N. (2020).
Antibiotic resistance in fish: Prevalence and
implications for public health. International
Journal of Aquatic Science, 19(3), 215-225.
https://doi.org/10.1016/j.ijaqs.2020.03.001
2.
Garcia, C., Mendez, A., & Sanchez, P. (2022).
Lactic acid bacteria as a biocontrol agent in
aquaculture: Mechanisms and applications.
Aquaculture Research, 53(4), 785-795.
https://doi.org/10.1111/are.13502
3.
Smith, K.E., Andermann, T., & Lambert, G.
(2021). Antibiotic resistance in aquatic
bacteria and the risk of transmission to
humans. Aquatic Microbiology Reviews,
24(1),
49-58.
https://doi.org/10.1016/j.aquat.2020.07.003
4.
Zeidan, M., Fawzy, A., & Hassan, R. (2023).
Evaluation of the antibacterial potential of
lactic acid bacteria isolated from fermented
foods. Journal of Applied Microbiology,
Volume 05 Issue 03-2025
8
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
05
ISSUE
03
Pages:
1-8
OCLC
–
1368736135
115(2),
345-355.
https://doi.org/10.1111/jam.14529
5.
Chen, X., Liu, Y., & Zhang, Y. (2021).
Mechanisms of antibiotic resistance in
bacteria isolated from aquaculture systems: A
review. Environmental Toxicology and
Pharmacology,
83,
103595.
https://doi.org/10.1016/j.etap.2021.103595
6.
He, Y., Song, H., & Zhou, J. (2020). The role of
probiotics in aquaculture: Enhancing fish
health and disease resistance. Fish & Shellfish
Immunology,
100,
16-25.
https://doi.org/10.1016/j.fsi.2020.02.002
7.
Velázquez, A., López, P., & Gutiérrez, L. (2020).
Potential of probiotics in aquaculture: Lactic
acid bacteria and their antimicrobial activity.
Fish
Pathology,
55(3),
137-147.
https://doi.org/10.3147/jsfp.55.137
8.
Yang, X., Zhao, L., & Hu, Q. (2021). Antibiotic-
resistant bacteria in aquatic systems: Insights
into detection, distribution, and resistance
mechanisms. Environmental Science &
Technology,
55(1),
102-115.
https://doi.org/10.1021/acs.est.0c06234
9.
Naeem, M., Jamil, M., & Raza, M.A. (2020).
Probiotic potential of lactic acid bacteria and
their role in aquatic disease management.
Aquatic
Toxicology,
231,
105725.
https://doi.org/10.1016/j.aquatox.2020.105
725
10.
Lee, D., Choi, T., & Kang, S. (2020). Resistance
patterns of bacteria isolated from farmed fish
and the potential for using lactic acid bacteria
in aquaculture. Aquaculture Research, 51(5),
1805-1814.
https://doi.org/10.1111/are.14755
