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Limnochemistry, diversity of plankton and ichthyofauna of some rivers of the Dooars region, West Bengal
(University of North Bengal, 2022) Sarkar Tapan; Pal Joydeb
The present study, entitled “Limnochemistry, diversity of plankton and ichthyofauna of some rivers of the Dooars region, West Bengal”, was conducted for a period of two years from March 2014 to February 2016. Three rivers, such as the Teesta, Jaldhaka, and Torsa, and two sites for each river, were selected for study. The study was conducted in three sections, such as physico-chemical parameters of river water, plankton diversity, and ichthyofaunal diversity. Temperature, pH, TS, TDS, TSS, DO, free CO2, chloride, TA, and TH were determined by standard methods. The Pearson’s correlation coefficient matrix, two-way ANOVA among seasons and sites, and one-way ANOVA between the two years were calculated using SPSS 16.0 and PAST 3.0 software. PCA was done by PAST 3.0 software.
The air temperature, water temperature, depth of water, pH, dissolved oxygen, electrical conductivity, total dissolved solid, total suspended solid, total solid, total alkalinity, total hardness and chloride showed seasonal variation in the three investigated rivers. The water temperature, pH, TDS, TSS, TS, total alkalinity, total hardness, and chloride did not show any significant differences among the six sites of the three investigated rivers, but the depth of water, DO, and FC showed significant differences among the six sites.
Water temperature is the most important parameter that controls other physico-chemical parameters of water. The pH, electrical conductivity, DO, TA, and TH of the three investigated rivers are within the optimum range, making them suitable for fish and other organisms. The DO and FC of the three investigated rivers indicate the good quality of water. Total alkalinity and total hardness indicate that the water of the three investigated rivers is soft in nature.
The PCA concentrates variances of the original data of physico-chemical parameters into two principal components (PC1 and PC2) in the case of rivers Jaldhaka and Torsa and three principal components (PC1, PC2 and PC3) in the case of the river Teesta. PC1 represents more physical and less chemical, while PC2 represents more chemical and less physical. WT, TDS, TH, and TA are the most influential factors.
A total of 24, 26, and 25 genera of phytoplankton belonging to five groups were recorded during the study period from the rivers Teesta, Jaldhaka, and Torsa, respectively. A total of 28 genera of phytoplankton were recorded from the three investigated rivers. Chlorophyceae was the most dominant group in all the three rivers.
Phytoplankton density, numbers of phytoplankton genera, Shannon-Wiener diversity index, and Margalef’s species richness index are positively correlated with pH, TDS, conductivity, dissolved oxygen, total alkalinity, total hardness, and chloride but negatively correlated with air temperature, water temperature, depth of water, TSS, and free CO2. Similar relations have been suggested by PCA.
A total of 17, 16, and 16 genera of zooplankton were obtained from the rivers Teesta, Jaldhaka, and Torsa, made up of protozoa, rotifera, cladocera, and copepoda. A total of 18 genera of zooplankton were recorded from the three investigated rivers. The density, number of genera, Shanon diversity index, and Margalef’s richness index of phytoplankton and zooplankton also showed seasonal variation in the three investigated rivers. The density and number of phytoplankton and zooplankton genera, Shannon-Wiener diversity index, and Margalef’s species richness index are positively correlated with pH, TDS, conductivity, dissolved oxygen, total alkalinity, total hardness, and chloride but inversely correlated with air temperature, water temperature, depth of water, TSS, free CO2. Similar relations have been suggested by PCA.
The density, number of genera, diversity index, and Margalef’s species richness index of phytoplankton and zooplankton are positively influenced by PC2, meaning affected by the chemical properties of water such as DO, TDS, TA, TH, and CL. The number of genera, diversity index, and Margalef’s species richness index of phytoplankton and zooplankton are negatively influenced by PC1. They are also negatively affected by the physical properties of water such as water temperature, TSS, TS, and free carbon dioxide. PCA biplots confirmed that phytoplankton and zooplankton density and/or number were the most influential factors which influenced the diversity indices.
A total of 147 fish species of ichthyoauna with remarkable variations in Teesta (140 species), Jaldhaka (119 species) and Torsa (131 species) were recorded. A total of 147 species belonging to 11 orders and 31 families were recorded over the study period from the three rivers. Out of 147 recorded species, 1 is Critically Endangered (0.68%), 20 (13.60%) are Endangered (EN) and 42 (28.57%) are Vulnerable (VU) (according to CAMP-NBFGR). But according to IUCN conservation status, 2 (1.36%) species are Endangered (EN) and 1 (0.68%) species is Vulnerable (VU). Out of 147 recorded species, 1 (0.68%) is Critically Endangered, 12 (8.16%) species are Endangered (EN), 23 (15.6%) species are Vulnerable (VU) and 33
(22.45%) species are near threatened (NT) (according to Barman). Of the total of fish species, only 10.20% (15 species) are endemic fish species recorded from the three rivers. Two endemic fish species are found only in North Bengal. CPUE, number of ichthyofauna genera, Shanon diversity index, and Margalef’s species richness index of ichthyofauna showed seasonal variation in the three investigated rivers.
CPUE, density, Shannon-Wiener diversity index, and Margalef’s species richness index exhibited significant and positive correlation with air temperature, water temperature, depth of water, TSS, TS, and free carbon dioxide but a significant and negative correlation with TDS, dissolved oxygen, conductivity, total alkalinity, total hardness, and chloride. Similar relations have been suggested by PCA. CPUE, NF, and DVF are influenced by PC1, meaning more physical parameters such as water temperature and depth of water, but negatively influenced by DO, TDS, TA, TH, and CL. PCA biplots revealed that CPUE and the number of fish genera were the most influential factors that influenced diversity indices.
Use of fine mesh size nets for fishing; river bed as an agricultural field; disposal of municipal waste; river embankment; presence of invasive fish species; mining of sand, gravel, and boulders from riverbed flood etc. are all threats to fish diversity.
Seedling Invigoration of Mung Bean Sprouts Through Matrix Bound Selected Elicitors Including Nano-Chitosan Under Salinity Stress
(University of North Bengal, 2023) Sen Sujoy Kumar; Bhandari Jnan Bikash
The short-duration leguminous warm-season crop, Vigna radiata (L.) R. Wilczek is now grown globally in a balanced manner, particularly in emerging nations. It maintains a special place in the human diet as a sprout, dahl, and in numerous other forms due to its wide nutritional range, speedy and easy preparation, excellent digestion, and anti-flatulent characteristics. Due to its high amounts of folate and iron and excellent protein content, mung bean is in high demand and commands a premium price, which makes the farmers happy. The lack of nutrient-dense food, specifically for poor vegetarians, combined with expanding population associated with increasing global food crises, and limited natural resources, made this nutritious food crop more crucial. Additionally, it has a symbiotic relationship with Rhizobium, which improves soil fertility by fixing atmospheric nitrogen and making it ideal for rice-based cropping systems and intercropping with other crops. Mung bean plants are occasionally broken up and buried in the soil to improve the nitrogen content of the soil. As a result, they also aid succeeding crop plants in meeting their own nitrogen needs. Despite having so many advantages, mung beans have received less attention than other pulse crops. Moreover, being a self pollinated pulse having a small sized genome, it might serve as a study model for other legumes.
But, the problem of rising salinity, one of the most serious global environmental issues, has been adversely hampering the overall mung bean productivity world-wide. An estimated 1.5 million hectares of agricultural area are lost to production annually due to high salinity levels present in the soil. More than 45 million hectares of the irrigated area have been ruined by salt globally. Alarmingly, it is anticipated that salinity will deteriorate over the next few decades. Plants are negatively impacted by salinity stress in many ways, including water stress, ion toxicity, nutritional issues, increased lipid peroxidation, metabolic process change, membrane disruption, reduced cell division, etc. These negative consequences altogether retard plant growth badly affecting its ultimate survivality. To provide humanity with a sufficient food supply and a balanced diet, scientists and researchers should show more interest in this subject. As a result, it's crucial to find and create mung bean cultivars with sustained resistance to this negative environmental pressure.
Numerous tactics were established over time to increase the quantity and quality of seedlings of various crop species. Seed priming is such a feasible, affordable, and successful method of reviving seeds. New priming techniques are constantly being developed around the world to improve the nutraceutical properties and yield of pulse crops. One such novel and innovative approach is Solid Matrix Priming (SMP). According to the literature review, SMP was relatively understudied compared to the other priming approaches and is being employed for the first time in mung bean (except our published papers). Impact of this less commonly used novel priming technique (SMP) in mung bean also demonstrates vast potential in seedling invigoration at a commercial scale that has yet to be investigated. Additionally, it is, in many ways, cost-effective, advantageous and superior to liquid priming as it is convenient to any seed size, very less amount of liquid is required (thus this is economical) and the slow absorption of liquid in this method allows to repair the damages, if any, occurred during liquid uptake (very fast liquid uptake in liquid priming frequently causes injury to cotyledons). Hence, farmers should be encouraged to use it on an extensive basis.
Moreover, going with the modern approach of seed nano-priming, assessment of the potential role of nano-chitosan as priming agent on mung bean is not investigated yet. Synthesizing novel nanoparticles like nano-chitosan using organic, biodegradable basic materials is gaining popularity because of its prospects for economical, ecologically friendly, and mass production. In the current study, after the synthesis of nano-chitosan using biodegradable chitosan as base material through the ionic gelation method in the laboratory, it was physiochemically characterized through Dynamic Light Scattering (DLS) and zeta potential studies, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray analysis (EDX), and Fourier Transmission Infrared Spectroscopy (FTIR).
The prepared nano-chitosan was then applied through SMP in mung bean under different concentrations of salinity stress to investigate its effect on the various seedling growth parameters, their biochemical and enzymological attributes, and salt-induced oxidative stress mitigation. The antioxidant activities of the treated mung bean seedlings under the said conditions were also studied. SMP noticeably enhanced the activities of antioxidant enzymes, namely Catalase (CAT), Peroxidase (POD), Superoxide dismutase (SOD), Polyphenol Oxidase (PPO), Ascorbate peroxidase (APX) activities in treated mung bean seedlings. At the same time, significant enhancement in the nutraceutical values of mung bean sprouts were also noted. Further, it noticeably reduces oxidative damages along with noteworthy
improvement in terms of tolerance capacity in mung bean seedlings exposed to salinity stress conditions.
The efficacy of nano-chitosan was also assessed for its antifungal activity against Aspergillus flavus, the most common mung bean seed-borne mycoflora, identified by the Indian Agricultural Research Institute (IARI), Delhi, India. Fungal spore germination and mycelial growth were rigorously examined after applying nano-chitosan in a dose-dependent manner with sterilization procedure modification.
To evaluate the effect of nano-chitosan following mung bean seed priming (SMP), Aspergillus flavus spore suspension was added to the seeds and allowed to germinate. After seven days of germination, various growth parameters of mung bean seedlings were measured, showing the highest antifungal activities with 571 mg/ml of nano-chitosan at a 10% matrix (Celite) moisture level. Accordingly, the current study revealed that SMP with nano-chitosan is an effective seedling invigoration treatment in saline settings, especially for mung bean seedlings in their early growth stages.
Thereafter, the treated and untreated mung bean seedlings under salt stress conditions were subjected to On-gel isozyme patterns of Native PAGE (α-Amylase, NADPH Oxidase, Superoxide dismutase, Peroxidase) and SDS-PAGE.
Orbitrap High-Resolution Liquid chromatography-mass spectrometry (OHR-LCMS) was conducted from SAIF, IIT- Bombay, to examine mung bean seedlings' most prominent and variably expressed SDS gel band particularly obtained in lane 3 represented by nano-chitosan treated seedlings in the gel image.
The High-Resolution Liquid chromatography-mass spectrometry (HR-LCMS) analysis of three significant isoflavones (Genistein, Formononetin, and Biochanin A) in control and chitosan and nano-chitosan treated mung bean seedlings grown under salt-stress conditions was conducted separately from SAIF, IIT-Bombay.
Further, the major mung bean isoflavones identified by the HR-LCMS study, were undergone through in-silico drug study (ADME and druggability test, prediction of pharmacological activities through PASS), and toxicity analysis (PRED SKIN, Pred-hERG Analysis, CarcinoPred-EL, Xenosite reactivity) using various online web tools in connection with their associated therapeutic implications. STRING and Cytoscape analysis were also performed to realize the interaction between the isoflavones and the salt stress genes in mung bean. The
metabolic shifts of chief isoflavones having therapeutic consequences were critically detected.
Further, to evaluate the impact of SMP with nano-chitosan in the genetic expression of some selected salt stress genes (SOS1, SOS2, SOS3, and NHX1) of mung bean, Quantitative Real Time PCR analysis of the treated (nano-chitosan primed) and untreated (control) mung bean seedlings was conducted from Credora, Life Sciences, Bengaluru, Karnataka. In every case, distinctly significant and enhanced expression of the selected salt stress genes were remarkably noted in the nano-chitosan treated seedlings compared to the untreated ones grown under salinity stress conditions. This clearly suggests that nano-chitosan (applied through SMP), is an ideal primer for seedling invigoration and salinity induced oxidative stress mitigation.
So, mung bean sprouts can be considered as a well-known healthier alternative and because of their prospective impacts on human healthiness and the industry's rapid growth, nutritional fortification of this functional food has become an important topic of study. Moreover, this work on mung bean may shed light on the functions of some associated salt-tolerant genes and the underlying molecular mechanisms of salt tolerance in mung bean crop plants.
Thus, in modern agricultural system, application of nano-chitosan through SMP might be a promising technique in stress mitigation, along with protecting and invigorating crop plants like mung bean against abiotic stress like salinity which in turn gives a conceptual foundation for the future study on the strengthening of mung bean's salt tolerance mechanism and the genetic resources. Further, based on the valuable characteristics like, antifungal and antioxidant activity, biodegradable and biocompatible nano-chitosan might be a potential substitute in place of commonly used toxic and non-degradable agrichemicals especially for the targeted beneficiaries and would also be helpful for the society and the environment in the long run.
Studies on the occurrence of antibiotic resistance and virulence in motile Aeromonas species from fish farming environments in sub-Himalayan West Bengal
(University of North Bengal, 2022) Mangar Preeti; Saha Aniruddha
Fisheries is an important source of commercial export in India and serves as a means of livelihood for the people at large. In India, West Bengal is a one of the leading producers of fish owing to its optimum agroclimatic conditions and inhabitants’ ingrained fondness for fish. Being placed at the foot hills of the great Himalayas, North Bengal holds unique endemism and icthyodiversity which set it as a class apart from rest of the state. Fishes are sometimes reared in small scale in homestead ponds, which forms the alternative sources of income among the rural population. However, fishes are reared without proper farm practices which leads to disease outbreaks with ultimate impact on the productivity.
The genus Aeromonas comprises of gram-negative bacteria widely disseminated in the aquatic environments. Mostly the members of these genus are opportunistic pathogens and capable of inducing diseases within a wide host range. Various researchers have reported the presence of these microorganisms in Epizootic-Ulcerative syndrome and haemorrhagic lesions in the fishes in Northern part of West Bengal. The primary goal of the present study comprised of analyzing the prevalence of Aeromonas sp. from water samples collected from fish farming environments of three districts of North Bengal. Secondly, the aeromonads were screened for virulence factors and its encoding genes responsible for pathogenic invasion of host. Thirdly, due to its abundance, the isolated aeromonads were evaluated for resistance against commonly used antibiotics and investigated for the underlying resistance genes.
The objectives of the present research were: (i) Isolation of Aeromonas spp. from fish farming environments in sub-Himalayan West Bengal. (ii) Biochemical characterization and phylogenetic analysis of bacterial isolates based on 16S rRNA gene sequence. (iii) Study of the virulence properties of the isolates of Aeromonas strains. (iii) Antibiotic sensitivity profiling of the bacterial isolates. (iv) Analyzing bacterial DNA for the presence of genetic
determinants of resistance and virulence. (v) Study the mobility of antibiotic resistance coding genes by in vitro conjugation.
For fulfilment of the objectives, water samples were collected from ten different small fish farming ponds distributed across three districts (Darjeeling, Jalpaiguri and Coochbehar) of North Bengal. The samples were subjected to microbiological processing which led to the isolation of total 83 putative Aeromonas strains in Aeromonas isolation medium. All these isolates were further screened by following the modified scheme of biochemical identification known as Aerokey-II which led to the identification of 34 strains as Aeromonas sp. The isolates were further confirmed to belong to this genus by PCR methods. The16S rRNA gene sequencing and BLAST similarity search revealed that the strains matched Aeromonas with percentage identity of the isolates as > 98%. The gene sequences were subjected to phylogenetic characterization and all the isolates rearranged to four reference strains: A. veronii (n=19), A. hydrophila (n=7), A. jandei (n=5) and A. caviae (n=3). The sequences were deposited in NCBI GenBank, and accession numbers were assigned to all the thirty-four isolates, viz. A. veronii (MT378391, MT379551, MT379645, MT379646, MT385145, MT380477, MT383121, MT383124, MT384421, MT384337, MT385097, MT396085, MT393933, MT393944, MT396230, MT396438, MT397061, MT397058, MT397063), A. hydrophila (MT378381, MT379550, MT379552, MT396436, MT396445, MT396437, MT395673), A. jandei (MT378390, MT393937, MT393941, MT393945, MT393942), A. caviae (MT393443, MT393930, MT393932).
The pathogenicity in Aeromonas is multifactorial and linked to a large number of genes that encode for various toxins and structural elements which aids proliferation within the host. In this study, six important virulence factors, hemolysin, protease, lipase, amylase, DNase and siderophore production were tested in all the 34 identified isolates of Aeromonas. Among the tested virulence traits, hemolytic and proteolytic activity was exhibited by 100% of the isolates. Amylase was detected in 70.6% of the isolates and DNase activity was detected in 44.10% of the isolates. Siderophore was
detected in 38.20% of the total isolates and a very small proportion of only 5.80% of isolates showed lipase activity.
Further, four important virulence genes aer/haem (encoding hemolysin), aspA (encoding alkaine serine protease), ascV (encoding type 3 secretion system) and flaA (encoding polar flagella) were analysed in all the 34 isolates identified as Aeromonas. PCR amplification of the genes revealed that 44.11% of the Aeromonas isolates carried the aer/haem and flaA genes. The ascV gene was found in 23.5% of the isolates. Only 8.82% of the aeromonads contained the aspA gene. The amplification products were cloned and sequenced. The sequences were subjected to similarity search using the BLASTn tool, annotated and submitted to the NCBI database through the BANKIT tool. The virulence genes have the following GenBank accession numbers: aer/haem (MT704303-MT704309; MT707932-MT707935; MH607886, MT591426, and MTT813045) aspA (MT909568-MT909570); ascV (MW001219-MW001222; MH607887-MH607890); and flaA (MT942623-MT942626, MT977537- MT977539).
Based on the combination of virulence genes found to be present in the Aeromonas isolates, the strains were classified into nine genotypic groups. Most of the Aeromonas strains belonged to group G that harboured only the flaA+ gene. The second common genotype among the isolates was aer/haem+, ascV+, flaA+. This study is the first to report the presence of such virulence genes from aeromonads isolated from this region. Furthermore, a virulent isolate of Aeromonas GP3 was able to transfer the aer/haem gene to E. coli DH5α via conjugation with an efficiency of 0.0394 X10-4 transconjugants per recipient cell. The detection of 23 kb plasmids in both donor and transconjugants corroborated to the transfer and gave an insight of the aer/haem being plasmid borne.
In order to validate the pathogenicity of the aeromonads six virulent isolates GP3, RB7, BP3, RJB1, MG8 and PP21 from different sampling sites and harboring atleast two virulence traits were injected into Anabas testudineus. The most harmful strain was GP3, which also possessed three of the four tested virulence-related genes (aer/haem+/ ascV +/flaA+) and five virulence
features (hemolysin, protease, DNase, siderophore, and amylase). On the other hand, strain PP21 which showed only two pathogenic phenotypes (protease and hemolysin) and the genes aerA/haem+ and flaA+, also showed 100% mortality. Contrarily, RB7, which exhibited four pathogenic phenotypes (hemolysin, protease, DNase, and amylase) and three genes (aerA/haem+/ascV+/aspA+), did not induce any mortality. In addition, BP3 was found to be very harmful to fishes despite only carrying one of the four genes under investigation which was ascV and exhibited four virulence characteristics. Therefore, in the current study it may be concluded that virulence phenotype expression and fish mortality were unrelated.
The isolated virulent Aeromonas sp. was further studied for its cytotoxicity in WRL-68 cell line (human, liver, embryonic). Results of this study revealed that the cell free culture filtrates of the Aeromonas strain GP3 were cytotoxic to human liver cells. Microscopic observation of the cells showed visible rounding off and detachment from the surface when compared against control cells, treated with cell free culture filtrate of Lactobacillus sp. (non-pathogen) with minor changes in morphology. The cell viability was reduced to 0.48% in GP3 filtrate treated cells as compared to 66% viability in Lactobacillus sp. treated cells. Hence the cytotoxic effect of GP3 on human cell lines implicating its pathogenic potential has been well established in this study.
In the current study, the partial nucleotide sequence of hemolysin amplified by PCR from GP3 was found to encode 185 amino acids. The 3D structure of the translated protein was constructed by homology modelling using a reference template 3COM (pro aerolysin of Aeromonas hydrophila) showing >90% homology. Further validation was done by PROCHECK software. Such modelling of the protein structure could prove to be beneficial for vaccine development and drug targeting of pathogenic aeromonads.
With the rise of diseases which hampers the fish productivity, numerous antibiotics are being used both as therapeutics and prophylactics that often leads to resistance among the bacterial populations. In this study resistance of the 34 isolates against 20 commonly used antibiotics for treatment of
diseases were assessed. In the current study 100% resistance was observed against penicillin and ampicillin followed by imipenem (85.29%), streptomycin (58.82%), cefoperazone (52.94%) and trimethoprim (50%). All the tested aeromonads exhibited resistance to three or more antibiotics. Intermediate level of resistance was observed against cefepime and cefuroxime (38.24%) and cefepime (23.53%). Maximum level of sensitivity was observed against chloramphenicol (91.18%) followed by norfloxacin (82.35%). Very high multiple antibiotic resistance (MAR) indices ranging between 0.15–0.7 in 94.1% of the isolates were observed which indicated that the aeromonads in fish farming environments have been exposed to antimicrobials. A MAR index > 0.2 indicates an environment with continuous exposure to antibiotics. A particular Aeromonas strain MG8 showing resistance against 14 antibiotics was found. Two strains, MG3 and HP6 showed resistance to 11 antibiotics, while strain PP19 showed resistance to 10 antibiotics.
Six significant clusters (C1-C6) were found using the Wards minimum distance approach in the hierarchical cluster analysis based on the antibiotic susceptibility phenotype represented as zone widths and sample sites of the 34 Aeromonas strains. The strains from different locations grouped to some extent under similar cluster depending on their levels of antibiotic resistance, like, all the Shivmandir isolates with low average MAR index value grouped in C2. However, variations in antibiotic resistance phenotype within a particular location was found to be the predominant feature. Therefore, it was concluded that resistance in aeromonads is irrespective of the location of sampling and the isolates had strain specific resistance pattern.
In the current study, genetic elements encoding antibiotic resistance known as integrons were screened for their presence in all 34 isolates. class I integrons (intI) were detected in 38.23% of the isolates with sizes ranging from 0.65 kb-2.5 kb. The integrons of 1.4 kb detected in FP2, MG8 and HP6 were cloned and sequenced. The NCBI accession numbers are MT424748, OP610544 and OP745416 respectively. The 1400 bp integron cassette of FP2 revealed the insertion of resistance gene cassettes of aadA4 and qacE providing resistance against aminoglycosides and quaternary ammonium
compounds respectively. The integron cassette of MG8 with a size of 1400 bp had the resistance gene casettes dhfrA1 and aadA1 providing resistance against sulfonamides and aminoglycosides respectively. The integron size of 1400 bp in isolate HP6 possessed dhfrA showing resistance against sulfonamides and a hypothetical protein of unknown function. Similarly, tetracycline resistance gene tetE encoding an efflux pump was detected in one isolate PP23 and the GenBank accession no. is given as OP745417.
Plasmids of sizes ranging between 1.6kb – 23 kb were present in a few isolates (PP7, RB5, GP1, MG9 and BP5) and all these plasmids were transferable to E. coli Dh5α by in-vitro conjugation experiments. Four isolates were able to transfer their 23 kb plasmid to E. coli Dh5α and the resistance markers of cefepime, cefuroxime, ampicillin, and oxytetracycline resistance could be traced in the recipients as well. Similarly, an isolate BP5 was capable of transferring 4.3kb and 1.6kb plasmids to the E. coli DH5α via conjugation. Conjugational transfer frequencies of 0.15 X 10-7 - 0.76 X 10-6 were obtained.
In conclusion, the current study reports the prevalence of Aeromonas sp. in small fish farming environments. The major findings of this study were the detection of virulence and antibiotic resistance in aeromonads along with underlying genes from three districts of West Bengal. The study has given a current scenario of the level of contamination of the fish farms by opportunistic pathogens like Aeromonas sp. The study may be helpful in spreading awareness among the fish farmers to adopt proper practices and avoid the disease outbreaks. Also, a clear picture regarding the level of antibiotic resistance in fish farms gives a picture about misuse of antibiotics. The data could be utilized to educate small scale farmers regarding the controlled use of drugs and antibiotics in fish culture.
Assessment of Therapeutic Potential and Phytochemical Profiling in Different Solvent Extracts of Centella asiatica
(University of North Bengal, 2023) Saran Kumar Gupta
Centella asiatica (L.) Urban, commonly known as Indian pennywort, a small perennial herb from the Apiaceae family has been used in traditional medicine for thousands of years. This study aimed to evaluate the effect of different extraction solvents on the therapeutic and phytochemical profiles of various parts of Centella asiatica. Among the various plant parts assessed, the leaves exhibited the best antioxidant and in vitro antidiabetic activity and the highest amount of phytoconstituents compared to petiole and root. Methanol was identified as the most effective solvent, yielding optimal IC50 values for DPPH (30.65 μg/ml) and ABTS (45.23 μg/ml). Additionally, the methanolic extract of leaves exhibited highest content of phenolics (65.49 mg GAE/g DW) and flavonoids (12.56 mg QE/g DW). The methanolic leaf extract also demonstrated a promising inhibition potential against α-amylase and α-glucosidase enzymes and possessed elevated levels of alkaloids, glycosides, tannins and terpenoids. This study demonstrated significant variations in the therapeutic potential of Centella asiatica, attributed to differences in the nature of the extraction solvents.
Morphological and Biochemical Characterization of Novel Cellulose and Starch Degrading Bacteria Isolated from the Rhizospheric Soil of Dendrocalamus minor and Musa sp.
(University of North Bengal, 2023) Chettri, Neha; Singh, Rishika; Misra, Megha; Sarkar, Sulagna; Toppo, Prabha; Bhandari, Jnan Bikash; Mathur, Piyush
The rhizosphere is the most active region of soil where plants and microorganisms live in close association and exhibit complex interactions. In the present study, rhizospheric soil samples were collected from bamboo and banana growing well in University of North Bengal campus. Cellulolytic and amylolytic bacteria were isolated from these samples through serial dilution technique and were identified on the basis of morphological and biochemical characteristics. The study showed presence of four isolates mostly from genera Bacillus sp. from rhizosphere of bamboo capable of degrading cellulose while five isolates (Rummeliibacillus sp., Lysinibacillus, Brevibacillus, and Bacillus) from rhizosphere of banana and degrade starch respectively. The study although preliminary but will prove valuable for the extraction of these enzymes from these rhizospheric isolates and will be highly appreciated for their application in biotechnology sector.