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International Journal of Aquaculture, 2014, Vol.4, No.18, 108
-
112
http://ija.biopublisher.ca
108
Research Article Open Access
Enzymatic Activities of Intestinal Bacteria Isolated from Farmed
Clarias
gariepinus
Ariole C. N. , Nwogu H. A., Chuku P. W.
Department of Microbiology, University of Port Harcourt, P.M.B. 5323, Port Harcourt, Rivers State, Nigeria
Corresponding author Email
International Journal of Aquaculture, 2014, Vol.4, No.18 doi: 10.5376/ija.2014.04.0018
Received: 03 Apr., 2014
Accepted: 18 May, 2014
Published: 04 Jun., 2014
Copyright © 2014
Ariole et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Ariole et al., 2014, Enzymatic Activities of Intestinal Bacteria Isolated from Farmed
Clarias gariepinus
, International Journal of Aquaculture, Vol.4, No.18:
108-112 (doi: 10.5376/ija.2014.04.0018)
Abstract
The culturable bacteria associated with the digestive tract of a freshwater cultured fish,
Clarias
gariepinus
, and their
degradative abilities were established. The spread plate method was employed for bacterial isolation. The bacterial isolates were
qualitatively screened for extracellular enzyme-producing ability using milk agar, starch agar, egg yolk agar and cellulose agar for
protease, amylase, lipase and cellulase activities respectively. A total of 18 bacterial isolates were identified. Bacteria of the genera
Bacillus
,
Staphylococcus
,
Vibrio
,
Aeromonas
,
Pseudomonas
,
Lactobacillus
,
Escherichia
,
Salmonella
,
Enterobacter
,
Micrococcus
and
Flavobacterium
were isolated from fish digestive tract at different frequencies with
Bacillus
predominating. Enzymatic studies
indicated that the bacterial isolates possess the ability to degrade proteins, starch, lipids and cellulose. The percentage composition of
enzyme-producing bacteria are - protease producing strains (72.2%), lipase producing strains (61.1%), amylase producing strains
(55.6%) and cellulose producing strains (38.9%). All the isolates possessed multienzyme activity. An isolate (
Bacillus
sp. B
1
) showed
activity for protease, amylase, lipase and cellulase enzymes. Therefore, the isolated indigenous multiple enzyme-producing strains
can be effectively exploited for use as probiotics while formulating aquafeeds.
Keywords
Gut bacterial flora; Freshwater cultured fish; Qualitative enzyme activity
Introduction
Aquaculture is an emerging industrial sector which
requires continued research with scientific and
technical developments and innovation (John and
Hatha, 2013). The African catfish,
Clarias
gariepinus
,
is of growing economic value in the African
aquaculture industry (Aldelhamid, 2009). The fish has
become one of the most important freshwater
aquaculture species in Nigeria and has a high market
value as table fish, being tasty and scaleless.
According to Thillaimaharani et al. (2012), the world
wide sustainability of the aquaculture industry
depends only on the inexpensive high quality feeds.
Therefore, microbial enzymes are very much essential
for the preparation of high quality functional feeds
through bioconversion of cost-effective feed materials.
The intestinal microflora and its metabolic activities
can be an important contributing factor in nutrition,
physiology and animal welfare (Tanu et al., 2012).
This is because the gut microflora in fishes and
crustaceans can metabolize several nutrients that the
host cannot and can convert them to end products that
are beneficial to the host (Suzer et al., 2007; Hoyoux
et al., 2009). It has been reported that intestinal
microorganisms have a beneficial effect on the
digestive process of fish such as in the microbial
breakdown of cellulose (Saha and Ray, 1998; Bairagi
et al., 2002; Saha et al., 2006; Mondal et al., 2008;
2010; Ray et al., 2010), starch (Sugita et al., 1997),
protein (Chong et al., 2002; Fu et al., 2005; Silvia et
al., 2006) and lipid (Tanu et al., 2012).
The gastrointestinal tract of fish, when compared with
the surrounding water, is rich in nutrients and confers
a more favourable environment for growth of
microorganisms (Saha et al., 2006). The bacterial flora
associated with the intestine of tropical estuarine fish
species such as
Tilapia
guineensis
has been
established (Ariole and Kanu, 2013). The intestinal
microflora of fish and shellfish has been reported to
aid in the secretion of inhibitory substances that
prevent colonization by bacterial pathogens (Berg,
1996; Sugita et al., 1998; Ariole and Anugwa, 2013;
Ariole and Nyeche, 2013; Ariole and Oha, 2013). The
microbial flora status in
Clarias
gariepinus
hatchery