Total bacterial load in the haemolymph of freshwater prawn Macrobrachium rosenbergii varied from 6.2x10⁴ to 1.9x10⁷ CFU/ml whereas in the hepatopancreas, bacterial load varied from 1.9x10³ to 2.9x10⁵ CFU/g. The total bacterial load in the pond water varied from 2.6x10² to 4.1x10⁵ CFU/ml. The isolated bacterial genera in the haemolymph and the hepatopancreas of prawn were Streptococcus, Acinetobacter, Micrococcus, Aeromonas, Vibrio, Flavobacterium,  Staphylococcus and Pseudomonas, whereas the detected bacterial genera in pond water were Micrococcus, Streptococcus, Vibrio, Flavobacterium,  Staphylococcus, Pseudomonas and Aeromonas. Among the detected genera, Vibrio and Staphylococcus were found to be dominant genera in the haemolymph of the sampled prawn throughout the study period whereas Staphylococcus and Pseudomonas were dominant in pond water

Chowdhury, M.B.R.

Hoq, M.E.

Islam, M.S.

Uddin, M.S.

Aquatic Commons

Bangladesh}. Fish. Res., 2(2), 1998 : 171-175 
Investigation on bacterial flora of farmed freshwater 
prawn (Macrobrachium rosenbergii de Man ) in 
Bangladesh 
M.S. Uddin, M.S. Islam, M.E. Hoq 1 and M.B.R. Chowdhury* 
Department of Aquaculture, Bangladesh Agricultural University 
Mymensingh- 2202, Bangladesh 
1 Fisheries Research Institute, Mymensingh-2201, Bangladesh 
* Corresponding author 
Abstract 
Total bacterial load in the haemolymph of freshwater prawn Macrobrachium 
rosenbergii varied from 6.2x1 a4 to 1.9x1 a7 CFU/ml whereas in the 
hepatopancreas, bacterial load varied from 1.9x1 a3 to 2.9x1 as CFU/g. The total 
bacterial load in the pond water varied from 2.6x1 a2 to 4.1 x1 as CFU/ml. The 
isolated bacterial genera in the haemolymph and the hepatopancreas of prawn 
were Streptococcus, Acinetobacter, Micrococcus, Aeromonas, Vibrio, 
Flavobacterium, Staphylococcus and Pseudomonas, whereas the detected 
bacterial genera in pond water were Micrococcus, Streptococcus, Vibrio, 
Flavobacterium, Staphylococcus, Pseudomonas and Aeromonas. Among the 
detected genera, Vibrio and Staphylococcus were found to be dominant genera 
in the haemolymph of the sampled prawn throughout the study period whereas 
Staphylococcus and Pseudomonas were dominant in pond water. 
Key words: M. rosenbergii, Haemolymph, Hepatopancreas, Bacterial flora 
Introduction 
Now-a.-.days freshwater prawn farming has turned to be a promising sector 
in Bangladesh since return from export earning of this commodity is 
considerable high. With the rapid development in Macrobrachium hatchery 
production and number of prawn grow-out farms, good husbandry and 
environmental problems developed as prawn were. stressed and weakened 
under adverse conditions. Moreover, shrimp is a highly putrescent fishery 
commodity as microbial activity is the most effective in producing undesirable 
odours and appearance in shrimp. Considering the importance of prawn fishery 
and the recent outbreak of shrimp disease in the country, a preliminary 
investigation was designed to investigate the bacteriological status in farmed 
prawn, Macrobrachium rosenbergii to know the monthlydistribution pattern of 
bacteria in different organs of prawn. 
M.S. Uddin eta/. 
Materials and methods 
Water and prawn samples 
Grow-out ponds under Jhalak Fish Farm- a private entreprenuer at Gouripur 
in Mymensingh were selected for sampling of freshwater prawn, 
Macrobrachium rosenbergii. Prawn samples were collected twice in a month 
and carried to the Fish Disease Laboratory of BAU in a plastic container 
containing the same pond water of the respective prawn samples. 
Prawn organs for bacterial isolation 
The prawn were stopped their movement by a simple hurt to the head. A 
disposable syringe was inserted into the cephalo-thorax region under the 
carapace to collect haemolymph from the heart of the prawn. An amount of 0.3 
ml haemolymph was mixed with 2.7 ml of physiological saline solution (0.85% 
NaCI) to make a stock suspension. Samples of hepatopancreas were collected 
with a sterile loop in a pre-weighted test tube. Suspension of hepatopancreas 
containing bacteria was made in physiological saline solution with the help of a 
vortex mixer. Necessary dilution were made by ten-fold dilution method. 
Inoculum (0.1 ml) was spread on TSA plates, incubated at 25°C and colonies 
were counted after two days of incubation. 
Determination of bacterial isolates 
Total number of bacteria were determined by counting the developed 
colonies on the triplicate plates of the same di I uti on after incubation. For 
determination of percentage composition, twenty colonies were seperated 
unbiasly from the total colonies grown in each of the plate having the number 
within 30 to 300 to obtain the pure culture and to characterize the isolates. From 
these plates of pure culture the isolates were preserved on TSA agar slant at a 
temperature of 4 °C and successive studies were performed for characterization 
of the isolates to identify them upto genus/group level according to the methods 
described by Cowan and Steel (1975) and Thoesen (1994) with slight 
modification. After the identification of bacterial genera/groups the percentage 
composition were determined on the basis of twenty isolates from pond water, 
haemolymph and hepatopancreas of the sampled prawn. 
Results and discussion 
The total bacterial load during the sampling period as varied from 6.2x1 0 4 to 
1.9x1 0 7 CFU/ml of haemolymph, 1.9x1 0 3 to 2.9x1 0 5 CFU/g of hepatopancreas 
and 2.6x1 02 to 4.1 x1 05 CFU/ml of pond water (Table 1 ). Total number of bacteria 
in the haemolymph of prawn varied with the months. The bacterial load of pond 
water was found to vary with months but they did not differ distinctly among the 
ponds studied. In pond water highest number of bacterial population was found 
in the month of July and the lowest in the month of November. 
172 
Bacterial flora in M. rosenbergii 
Table 1. Monthly variation of the total bacterial load in the haemolymph, hepatopancreas 
of M. rosenbergii and pond water 
Months 
July 
August 
September 
October 
November 
December 
Haemolymph 
(CFU/mi) 
5 
1.7x10 
7.0x10 4 
1.3x1 0 5 
2.3x1 0 6 
6.2x1 0 4 
3.9x1 0 
6 
Total load of the bacterial genera 
Pond-1 
Hepatopancreas Water Haemolymph 
(CFU/g) (CFU/mi) (CFU/ml) 
4 4 7 
4.9x10 2.5x10 1.9x1 0 
3.0x10 
3 
1.6x1 0 
3 
2.6x10 
6 
3 3 6 
4.6x10 2.2x1 0 1.3x1 0 
3 3 4 
4.6x10 1.7x1 0 9.6x10 
5.0x10 3 8.6x1 0 2 4.6x1 0
5 
1.9x1 0 
3 
2.3x1 0 
3 
2.7x10 
4 
Pond-2 
Hepatopancreas Water 
(CFU/g) (CFU/ml) 
2.9x10 
5 4.1x1 0 5 
3.7x10 4 1.9x1 0 
4 
3.6x1 0 4 8.5x1 0 
3 
4.2x10 4 2.4x1 0 
3 
8.4x1 0 3 2.6x1 0 2 
4 
3.3x1 0 1.6x1 0 3 
The bacterial genera/groups detected in the haemolymph and 
hepatopancreas of the prawn were tentatively Streptococcus, Acinetobacter, 
Micrococcus, Aeromonas, Vibrio, Flavobacterium, Staphylococcus and 
Pseudomonas (Table 2), whereas the detected bacterial genera in pond water 
were Micrococcus, Streptococcus, Vibrio, Flavobacterium, Staphylococcus, 
Pseudomonas and Aeromonas (Table 3). The identified bacterial genera 
recovered from the haemolymph were found throughout the study period 
except Acinetobacter, and Vibrio was found to be dominant genera in the 
month of August. Flavobacterium and Staphylococcus were found to be 
dominant in the hepatopancreas of prawn. 
Table 2. Monthly distribution of bacterial genera in the haemolymph and hepatopancreas 
of cultured M. rosenbergii 
Months Prevalence of the bacterial genera 
Haemolymph Hepatopancreas 
Str. Aci Mi. A e. Vi Fl. Sta Ps. Str Aci Mi. Ae Vi Fl Sta Ps. 
July. 11 Nd 14 14 20 19 08 12 15 03 13 12 03 24 26 08 
Aug. 12 Nd 13 14 37 03 20 OS 17 05 13 13 07 13 23 13 
Sep. 09 12 11 10 19 18 20 07 09 15 19 13 Nd 14 21 10 
Oct. 11 24 03 11 10 Nd 20 24 09 13 19 17 15 14 22 11 
Nov. 08 12 13 17 14 07 10 20 18 09 13 12 07 13 24 13 
Dec. 10 03 12 20 23 05 20 09 15 03 11 13 03 23 24 11 
Str Streptococcu Aci Aci netobacter Mi Micrococcus 
Ae Aeromonas Vi Vibrio Fl Flavobacterium 
Sta Staphylococcus Ps Pseudomonas Nd Not detected 
173 
MS. Uddin eta/. 
Table 3. Monthly distribution pattern of bacterial genera in pond water 
Months Prevalence of the bacterial genera 
Pond-1 Pond-2 
Mi. Str. Vi. Fl. Sta. Ps. Mi. Ae. Vi. Fl. Sta. Ps. 
July 07 06 20 07 30 30 22 12 Nd 28 38 Nd 
August 35 10 12 13 15 15 12 08 10 30 40 Nd 
September 20 08 12 15 22 23 13 15 08 27 32 05 
October 13 22 08 12 23 22 15 23 Nd 27 27 08 
November 15 30 10 15 15 15 03 22 OS 20 25 25 
December 10 12 18 20 20 20 10 27 Nd 22 18 23 
Mi: Micrococcus Str : Streptococcus Vi: Vibrio 
Fl Flavobacterium Sta : Staphylococcus Ps : Pseudomonas 
Ae : Aeromonas Nd : Not detected 
Qualitative and quantitative composition of bacteria in different organs of the 
prawn investigated were found to vary with months, organs and pond water 
also. In the study period, the bacterial load in the haemolymph of prawn were 
higher than those in hepatopancreas or pond water. Environmental factors such 
as water temperature, pH, dissolved oxygen, nutrients, organic substances etc. 
might be the causal factors of these variations. Besides these supplementary 
feed to prawn were the sources of organic substances. Bacterial growth in water 
was influenced by availability of carbon and energy source (Marshal 1985). Udea 
eta/. (1992) mentioned that the microflora associated with the growing prawn 
significantly influenced by the environmental conditions. Total load of bacteria in 
the haemolymph of prawn was higher in summer than in winter due to the 
differences in the ambient temperature (Zuberi eta/. 1992, Fonseka and Ranjini 
1995). 
Poor water quality and high organic loading are associated with shell lesion 
including bacterial growth in grow-out prawn. A variety of bacteria, producing 
extracellular lipases or protease such as Aeromonas, Pseudomonas, Vibrio, 
Benekea spp. have been implicated in shell disease (Cook and Lofton 1973). 
Organic matter supplied as feed to pond and manure increased the bacterial 
load in pond water (Moriarty 1986). In most of the months, Vibrio and 
Pseudomonas were high in the haemolymph of prawn investigated which is 
similar with the findings of Lombardi and Labao (1991 a and 1991 b), mentioned 
Pseudomonas, Vibrio etc. as the possible causative agents of prawn diseases. 
Although pathogenicity and antibiotic test were not performed in the present 
study, the isolated bacteria Pseudomonas, Vibrio and Aeromonas could be 
pathogens to the cultured prawns which needs further study. 
174 
Bacterial flora in M. rosenbergii 
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(Manuscript received 3 August 1997) 
175 


Investigation on bacterial flora of farmed freshwater prawn (Macrobrachium rosenbergii de Man) in Bangladesh

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Investigation on bacterial flora of farmed freshwater prawn (Macrobrachium rosenbergii de Man) in Bangladesh

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