Effect of tetracycline on lemna minors population growth biology essay

This probe was designed to analyze the consequence of low concentrations of Achromycin on population growing rate of Lemna child.

Lemna fronds were cultured in solutions made up of Sach alimentary solution of fixed volume and Achromycin of variable concentrations at 0 % , 0. 00125 % , 0. 0025 % , 0. 005 % , 0.

01 % and 0. 02 % for seven yearss under the same temperature and light strength. On the 7th twenty-four hours, frond figure in each Petri dish was recorded and growing rate was determined utilizing expression. Consequences indicated that the higher Achromycin ‘ s concentration, the lower the growing rate. At 0.

02 % , growing was wholly inhibited. Pearson Product-Moment Correlation Coefficient analysis proved a statistically important negative linear relationship between Achromycin concentration and population growing rate at 5 % important degree, back uping the experimental hypothesis. Hence it can be concluded that Lemna minor population growing rate lessenings as tetracycline concentration additions. Cardinal words: Tetracycline ; Lemna child ; growing rate

Research and Rationale

This probe aims to execute a bio-assay to analyze the relationship between low concentrations of Achromycin and population growing rate of Lemna child. Bioassay refers to a scientific process to mensurate the extent of toxic effects of a specific chemical contamination on a figure of one specific sensitive species by exposing them to a scope of concentrations of the chemical over a period of clip [ 1 ] .

Increasing figure of scientific publications about the happening and impacts of pharmaceuticals in the aquatic environment [ 5 ] is reflecting concerns on these substances being of import beginnings of chemical pollution in this modern age. Among all curative categories, antibiotics have been actively studied owing to their comparative important sums detected in the environment. Figure Relative per centums of therapeutics detected in the environment. [ 5 ]Antibiotics are curative agents capable of killing or suppressing growing of micro-organisms including bacteriums, Fungis and protozoa [ 6 ] . Extensive use in aquaculture, human and veterinary medical specialty means that both excreted metabolites and unchanged parent compounds of antibiotics can easy come in the aquatic ecosystem through the discharge of human, farm animal, infirmary and pharmaceutical industry wastes every bit good as the disposal of unwanted or expired merchandises.

Despite of utile curative application antibiotics offer, the same belongingss are frequently reported to post negative impacts on other non-target beings in the ecosystem. hypertext transfer protocol: //www. informaworld. com/ampp/image? path=/713610645/769414508/bose_a_198494_o_f0001g.

pngFigure Pathways of Pharmaceutical Contamination of Aquatic Environment [ 2 ]hypertext transfer protocol: //xray. bmc. uu. se/~kurs/BiostrukfunkX2/practicals/practical_4/practical_4_files/Tetracycline. gifFigure Chemical construction of tetracycline [ 3 ]Tetracycline is a protein synthesis inhibitor with a basic construction of four amalgamate six-membered rings. Tetracyclines are wide scope antibiotics which are effectual against many aerophilic and anaerobiotic Gram-positive and Gram-negative bacteriums. They interfere with protein synthesis in bacteriums by forestalling aminoacyl-tRNA from adhering to the acceptor ( A ) site on 30S ribosomes [ 4 ] .

This is done by altering the forms of proteins and ribosomal RNA in the ribosomes so that aminoacyl-tRNAs are no longer compatible to the binding sites. Consequently, codons on courier RNA can non be translated into polypeptide sequences. Without proteins, bacteriums are halted from turning and reproducing but non killed – Achromycins are bacteriostatic.

In the USA, Achromycins have been detected at a concentration of 110 ngl-1 in surface H2O [ 5 ] . Although this concentration is still low to do any important effects on aquatic species at the present minute, Achromycins ‘ happening in the environment, like any other pharmaceuticals should be given considerable attending since their sum might increase in the hereafter. Previous plants have reported some beliing grounds about the consequence of Achromycins on Lemna species ‘ growing.

One reported stimulatory consequence for concentration between 1 to 10 I? gl-1 and strong inhibitory consequence at 1000 I? gl-1 [ 14 ] while another survey utilizing a mixture of Achromycins indicated no repressive consequence on Lemna child ‘ s close comparative, Lemna gibba ‘ s growing rate [ 10 ] . Lemna child is a member of household Lemnaceae ( duckweed ) . This emergent species reproduces by vegetive budding – turning more foliages ( fronds ) and finally divide into new persons. Lemna child is an ideal index species for this survey due to several grounds. First, its short life anticipation allows the experiment to be designed for a short period of clip. Due to aggressive belongings under nutrient-rich conditions and demand of minimum infinite for growing, Lemna child can be easy cultured in nutrient-rich solution in Petri dishes. More significantly, a old survey has found that Lemna child is the most sensitive species towards pharmaceuticals in many instances in comparing to other trial species, viz.

Daphnia Magma and Desmodesmus subspicatus [ 7 ] . Figure Lemna minor construction from top positionThere are assortments of methods in mensurating the growing of Lemna minor including root figure, works figure, frond figure, root length, frond diameter, dry mass and wet mass. Frond ( leaflike construction ) figure was chosen as the parametric quantity for this probe since this method is simple, fast and non-destructive.

Growth rate can be calculated utilizing the undermentioned equation [ 8 ] : Where R = ( population ) growing rate per twenty-four hoursxt1 = concluding figure of frondsxt0 = initial figure of frondst1 = concluding twenty-four hours of experimentt0 = first twenty-four hours of experimentTo let computation of growing rate based on this expression, a species must be density independent, small-sized, develops quickly, reproduce early, and has a short lifetime [ 15 ] [ 16 ] . Lemna minor fulfil all these standards. Therefore, this probe is an effort to use the construct of index species to research the side consequence of antibiotics on non-target being in the aquatic environment.

Experimental Hypothesis

The higher the concentration of Achromycin, the lower the population growing rate of Lemna child.

Null Hypothesis

There is no correlativity between different concentrations of Achromycin and population growing rate of Lemna child.


Trial 1This is to corroborate Achromycin ‘ s repressive consequence on Lemna child ‘ s growing. Lemna minor fronds were cultured in two Petri dishes with the first containing mixture of pool H2O and tetracycline solution and the 2nd incorporating merely pool H2O for 5 yearss.

The figure of fronds was counted and recorded on a day-to-day footing. TableConsequence of Trial 1SolutionFrond figure on twenty-four hours01234Pond H2O ( control )1010181920Pond H2O + 2 cm3 of 1 % Achromycin1010101010Tetracycline wholly inhibited Lemna child ‘ s growing and the fronds even turned brown on the really first twenty-four hours. Meanwhile in the control, Lemna minor continued turning new fronds and remained green throughout the 5-day-period. The span of the experiment should be increased to better see the consequence of Achromycin on the species ‘ growing. To supply optimal nutrition status for Lemna child, pool H2O was decided to be replaced by Sach mineral solution. Trial 2This is to work out a suited scope of tetracycline concentrations to be used in the experiment every bit good as to find suited twenty-four hours for t1.

Similar method as in Trial 1 was applied. Concentrations chosen were 0. 1 % , 0. 075 % , 0. 05 % , 0. 025 % , 0. 0125 % and 0 % . For each concentration, 22.

5 cm3 of Sach mineral solution was assorted with 2. 5 cm3 tetracycline solution of 10 times the needed concentration. Different concentrations of Achromycin were prepared by consecutive dilution method. Lemna minor were allowed to turn for 7 yearss. TableConsequence of Trial 2Concentration ( % )Initial frond figureFrond figure on the 7th twenty-four hoursGrowth rate ( n day-1 )0. 000010260. 13650. 012510150.

05790. 025010100. 00000. 050010100. 00000. 075010100. 00000.

100010100. 0000The population growing of Lemna child was wholly inhibited even at a concentration every bit low as 0. 0250 % . Hence it was decided that the scope should be farther lowered. Seven yearss was found to be a suited span for the experiment. For the existent experiment, 15 fronds would be used for each Petri dish in order to increase the statistical significance of informations obtained.


Manipulated: Concentration of Achromycin ( % )Reacting: Growth rate per twenty-four hours, R ( n day-1 )Changeless: Initial figure of fronds ( 15 per Petri dish ) , initial size of fronds, volume of Sacch ‘ s solution in each Petri dish ( 22. 5 cm3 ) , light strengthand temperature ( placed in same country outside the research lab ) .


Petri dishes, 10 cm3 and 25 cm3 mensurating cylinders, calibrated dropping pipette, forceps and beakers.


1 % tetracycline solution, Sacch ‘ s alimentary solution, distilled H2O, Lemna child workss and labelling spines.

Experimental Procedure

Six Petri dishes were labelled as 0 % , 0. 00125 % , 0. 0025 % , 0.

005 % , 0. 01 % and 0. 02 % . Consecutive dilution method was used to fix tetracycline solutions of concentrations 0. 0125 % , 0. 025 % , 0.

05 % , 0. 1 % and 0. 2 % from 1 % Achromycin. 25 cm3 mensurating cylinder, 10 cm3 mensurating cylinder and calibrated dropping pipette were used to mensurate out Sach alimentary solution and tetracycline solution into each Petri dish as follows: TableConcentration required ( % )Volume of Sach Nutrient Solution ( cm3 )Concentration of tetracycline solution used ( % )Volume of tetracycline concentration used ( cm3 )0. 0000025.

00. 00000. 00. 0012522. 50. 01252.

50. 0025022. 50. 02502. 50. 0050022. 50.

05002. 50. 0100022.

50. 10002. 50. 0200022. 50. 20002. 515 Lemna fronds of similar sizes were picked out from pool H2O, rinsed in a beaker of distilled H2O and placed in Petri dish labelled 0 % .

Measure 4 was repeated for concentrations 0. 00125 % , 0. 0025 % , 0. 005 % , 0. 01 % and 0. 02 % .

Stairss 1 to 5 were repeated to bring forth another two set of replicates. All Petri dishes were placed in a bright country and left for seven back-to-back yearss. Frond figure was counted on the 7th twenty-four hours and recorded. P1010811. JPGFigure Set up of experiment

Hazard Appraisal

Eyelids of Petri dishes were ever put on except when reassigning Lemna child into the civilization solutions. This is to forestall taint of civilization solutions. Lemna minor fronds were rinsed in a beaker of distilled H2O before being placed in civilization solution to forestall any unnoticed little buds sticked to them from making false image of new frond growing.

Baseball gloves were worn when covering with Lemna child from pool H2O to forestall bacterial infection. During frond numeration, any seeable protruding bud was counted as single frond regardless of size to avoid prejudice. If any uncertainness arises, numeration was repeated to obtain accurate consequences.


TableConcentration ( % )Initial frond figureFrond figure on the 7th twenty-four hoursAverage frond figure on the 7th twenty-four hoursReplicate 1Replicate 2Replicate 30. 0000015383233340. 0012515252521240.

0025015222323230. 0050015202121210. 0100015182018190. 020001515151515Sample computation of growing rate per twenty-four hours: Graph

Statistical Analysis

Pearson product-moment correlativity coefficient ( PMCC ) was chosen to mensurate the extent of additive dependance between concentration of Achromycin and growing rate of Lemna child.

Coefficient R indicates the strength of relationship which ranges from -1 to +1. 0 value means no correlativity. The scope between -1 and 0 represents negative correlativity ; the further the value lies to the left, the stronger is the negative correlativity with -1 stand foring the perfect negative correlativity value. The opposite is true for the positive scope.

TableTable for computation of PMCC valueten00. 001250. 00250. 0050. 010. 02I? x= 0. 03875Y0.

116900. 067140. 061060. 048070.

033770. 00000I? y= 0. 32694×201. 562×10-66.

25×10-60. 0000250. 00010. 0004I? x2= 0. 000533y20. 0136660.

004507780. 0037280. 0023110. 001140. 0000I? y2= 0. 025353XY00. 0000839250.

0001530. 000240. 0003380I? xy= 0. 000815*SS = Sum of SquaresFormula to happen correlativity coefficient, RR = 0. 8886 & gt ; 0. 0811 ( critical value ) for 5 % important degreeAnalysis utilizing PMCC showed a statistically important negative linear relationship between concentration of Achromycin and Lemna ‘ s population growing rate since the deliberate R value was greater than critical value at 5 % important degree.

Therefore, void hypothesis can be rejected.

Datas Analysis

From Table 4 and Graph 1, it is clear that the general tendency shows a diminution in Lemna child ‘ s growing rate per twenty-four hours as the concentration of Achromycin increased. This negative correlativity is verified by statistical analysis utilizing PMCC. At 0 % , Lemna child recorded growing rate of 0. 1169. This is the normal growing rate under nutrition-rich fortunes. The graph shows a steep diminution in growing rate when Achromycin concentration increased to 0. 00125 % where growing was inhibited up to about 43 % .

This is followed by a slower and about additive lessening in subsequent concentrations. At 0. 02 % , Lemna child was wholly inhibited from turning new fronds. Although no noticeable anomalousnesss were found in the information, the lessening in growing rate from 0. 00125 % to 0. 0025 % might non be needfully uncovering a true diminution since the average Numberss of fronds between the two concentrations merely differ by 1 and the per centum lessening in growing rate was merely approximately 5 % . Several beginnings of mistakes that could give rise to incompatibilities in the set of informations were noted. First of wholly, the concentrations of tetracycline solutions prepared might non be exact due to restrictions in truths of mensurating cylinder and dropping pipette.

Besides, solutions evaporated faster in some Petri dishes and slower in others, taking to changes in concentrations of Achromycin throughout the seven yearss.


The information does non uncover the part of stimulatory consequence on growing as found in old survey. This is because the scope of tetracycline concentration used is far above the concentrations matching to this part, i. e. 1-10 I? gl-1.

Hence, it can be said that there might be hidden tendencies in the alteration in Lemna child ‘ s growing rate between 0 % and 0. 00125 % , the steep part of the graph. Apart from that, the diminution in growing rate at higher concentrations supported repressive consequence of Achromycin found in old survey.

Hence the findings of this survey could be considered valid. Although old surveies have proven Achromycin ‘ s toxicity towards aquatic macrophytes like Lemna child, the exact mechanism is still an uncertainness. It is interesting that receptors for Achromycins have been identified in workss, proposing an uptake mechanism [ 6 ] . It is really likely that tetracycline inhibits Lemna child ‘ s growing by the same manner of action against bacteriums – protein synthesis suppression, harmonizing to several published diaries. For case, the yellowing consequence of Achromycin in some workss was related to the suppression of translational activity of chloroplast [ 9 ] . Chlorotetracycline, which is similar in construction to tetracycline, was found to be able to suppress protein synthesis including chloroplast synthase [ 9 ] .

Furthermore, when tested with several photosynthetic beings, Achromycin was found to be toxic [ 10 ] . Another suggestion is that Achromycin complex mineral foods, forestalling soaking up by Lemna, therefore doing mineral lack and inhibits growing [ 10 ] . Tetracyclines are besides known to act upon the production of abscisic acid ( ABA ) , a type of works emphasis endocrine involved in growing ordinance [ 14 ] . An of import restriction in this experiment was that no information could be obtained about the destiny of Achromycin in civilization solutions throughout the 7-day-period.

There are findings saying that Achromycin is an unstable compound which is easy hydrolysed in H2O and interrupt down by sunlight [ 11 ] ; this could be measured utilizing HPLC-UV/VIS spectrophotometer [ 10 ] . However, in another survey the efficiency of debasement has been proven low, runing from 10-20 % [ 12 ] . Another beginning stated that Achromycin is non-biodegradable in 28 yearss [ 17 ] . If Achromycin did undergo debasement, the concentration of Achromycin would diminish over clip.

However, this should non significantly affect the consequence since the span of the experiment was comparatively short and the rate of debasement should be reasonably unvarying in all samples since they were subjected to the same temperature and light strength. Besides, although fronds chosen ab initio were of similar sizes and consisted of one foliage merely, they were non all at the same degree of adulthood. Therefore, new fronds could develop faster in some and slower in others. However this is compensated by adequate figure of replicates. Frond numeration method has a few disadvantages.

To avoid prejudice, little buds that protrude were wholly counted as single fronds. A little bud may be less than 5 % the biomass of a healthy normal frond but both were considered equal when frond numbering method was applied [ 13 ] . Therefore, frond figure is non an accurate step of growing in footings of biomass. Meanwhile, frond numeration did non reflect the position of fronds – alive or dead [ 13 ] . Alteration can be done to this experiment by increasing figure of fronds used and mensurating dry or wet mass of fronds on the seventh twenty-four hours. This is a more accurate agencies of finding growing rate.

Excluding dead fronds in measurings should break bespeak population growing since merely populating persons are considered to be included in any population. To farther widen this probe, similar set up can be applied to compare effects of same concentrations of different categories of antibiotics on Lemna child, for illustration sulphonamides, macrolides, glycopeptides and quinolones [ 6 ] . Different antibiotics may either stimulate or inhibit Lemna child ‘ s population growing.

In add-on, mixtures of pharmaceuticals could be tested on Lemna child. This gives a better image of existent state of affairss in the aquatic ecosystem because a drug usually does non be entirely in the environment. Besides, different species such as algae and Daphnia magma could replace Lemna child as the trial species since different species have different sensitivenesss towards pharmaceuticals, although the usage of Daphnia magma may raise ethical issues.


The survey showed that as tetracycline concentration additions, Lemna child ‘ s population growing rate lessenings.

PMCC statistical analysis has proven a statistically important negative correlativity between tetracycline concentration and growing rate. A 100 % growing suppression was achieved at 0. 02 % . Although the mechanism has non been confirmed, it is clear there are underlying physiological causes behind Achromycin ‘ s toxicity towards Lemna child. Hence, the experimental hypothesis is accepted and the void hypothesis is rejected.

Beginning Evaluation

This single probe was greatly referred to a figure of on-line scientific diaries from Science Direct from subscribed by UiTM Library EZAccess service.

Science Direct is a world-leading online database supplying more than 2, 500 peer-reviewed diaries, more than 11, 000 books and more than 9 million full-text articles. Thus it is a extremely dependable beginning of diaries. Beginning 5 from Science Direct has provided a great trade of information about antibiotics, their use, happening and effects these on the environment. Data summarised in this diary were besides derived from beginnings 11 and 14, bespeaking that these diaries are of import mentions among the scientific community. Beginning 16 summarised of import standards in choosing index species for ecological impact appraisals, assisting the procedure in taking Lemna child as the most suited being to be used in this probe.

These include copiousness, biogeographic distribution, population stableness, length of service, organic structure size, ecological importance and sensitiveness which cross-refer to identify points highlighted by on-line beginning 13 which stated that macrophytic species such as Lemna are “ of import in O production, alimentary cycling, control of H2O qualityaˆ¦ ” ( ecological importance ) and “ relevant to many aquatic environments including lakes, streamsaˆ¦ Duckweed workss are widely distributed in the worldaˆ¦ ” ( biogeographic distribution ) .