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Assam Agricultural University, Jorhat
Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level.
Genesis of AAU -
The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati.
Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.
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ThesisItem Open Access GENETIC STUDIES FOR IMPROVING YIELD UNDER DROUGHT STRESS ENVIRONMENTS IN RICE OF ASSAM(2019-07) PARRAY, ROUF AHMAD; Baruah, Akhil RanjanDrought is a major limiting factor for rice under rainfed ecosystem in Assam. In this context, thirteen rice cultivars with varied level of drought tolerance were chosen from a set of 272 different rice genotypes based on a field experiment conducted during 2014-15 season under drought. The thirty days old seedlings of 13 cultivars were tested for extensive morpho-physiological, biochemical parameters, relative transcript accumulation and global gene expression using next generation sequencing (NGS) method, and data were recorded at fifth, tenth and fifteenth day of withholding water (DWW) in order to obtain detail trait based gene architecture and to improve high yielding variety of Assam using transcript dynamics. Among the physiological traits studied, stomatal conductance decreased as the dehydration stress increased but the effect was minimum in Apo, Dumai and Tepi Dumai compared to others. Photosynthetic rate decreased with increasing water deficit, but the effect was less pronounced in Apo, Dumai and Tepi Dumai. The rate of transpiration decreased upto 5DWW but gradual increase was observed in later stage. Moreover, the fall in transpiration rate was less in Apo. Water use efficiency (WUE) of rice plants was enhanced significantly under moisture stress at all the three periods of stress (5DWW, 10DWW, 15DWW) in Apo, Tepi Dumai and Dumai. Reduction in RWC was experienced across all genotypes but the decrease was less prominent in Apo, Dumai and Tepi Dumai. Drought stress condition led to increased proline content across genotypes as compared to irrigated condition. Apo, Tepi Dumai, Dumai and Kali Murali showed rapid increase compared to others. Increase in root length was observed across all cultivars with Apo being the longest followed by Dumai and Ranjit. Then, five drought responsive pathway genes (OsDREB2, OsNAC1, bZIP16, OsbZIP 23, OsbZIP72) were chosen to check the differential expression patern in the cultivars at the same data point as mentioned above. Expression profiling of OsDREB2 showed significant increase in gene expression with increase in drought stress in the case of Apo and Dumai. Significant expression of the OsNAC1 was found in Apo, Dumai at different time points of dehydration stress whereas expression of ARC 10372 was prominent in 15DWW. Apo showed significant difference in expression of bZIP16 under all the three stages of water stress whereas Dumai and Ranjit showed enhanced expression compared to other cultivars. Expression profile of OsbZIP23 showed significant accumulation of transcripts in Apo in all stages followed by Dumai. Significant expression of OsbZIP72 was observed in Apo at 10DWW and 15DWW followed by Ranjit and Dumai. Based on the results of morpho-physiological, biochemical and expression analysis, three cultivars, viz., Ranjit, Apo and Dumai were chosen to study the detailed transcriptome at only 10DWW. Transcriptome profile revealed highest mapped genes in Dumai followed by Ranjit and Apo, however, only 14.5% genes were in common. Ranjit was found to be more responsive to abiotic stimulus including water stress. Gene ontology (GO) suggested no significant change of pathway genes upto 10 DWW among the three cultivars. The transcriptome data were validated using five differentially expressed genes in these three cultivars along with a F4 mapping population. It revealed similar trend, suggesting the present transcriptome data set was in good fit. However, detail transcriptome study in vital plant parts at different stages under drought stress will throw more light about the interaction of pathway genes to adress the problem better.ThesisItem Open Access Molecular characterization and nutritional equivalence evaluation of transgenic chickpea expressing either a cry1Ac or cry2Aa gene(AAU, Jorhat, 2019-10) Gupta, Rubi; Sarmah, Bidyut KumarBiosafety assessment of transgenic chickpeas having B.thuringiensis genes for resistance to pod borers is a regulatory requirement and mandatory to document before releasing in the field. Therefore, Bt chickpea lines harbouring either a cry1Ac or cry2Aa gene were characterized for the presence and expression of the transgene in their advanced generations, biosafety assessments and transcript profile were studied. The homozygous lines were selected for comparative nutritional equivalence assay. Biochemical estimations of major nutritional components such as proximates, vitamins, minerals, fatty acids and anti nutrients confirmed that the Bt chickpeas lines are nutritionally equivalent to their non-transgenic counterparts and the seed composition is similar or within the range reported, previously. Seed protein quality was investigated by separating the proteins in PAGE and eluted proteins after mass spectrometry (MS) showed expected fractions of 11S legumin, 7S vicilin, and 2S albumin of chickpea storage proteins in the transgenic lines. The protein digestibility was assayed using the multi-enzyme system and transient pepsin hydrolysis to mimic simulated gastric fluid followed by trypsin hydrolysis to mimic simulated intestinal fluid. Total seed proteins of both the transgenic and nontransgenic lines were digested at a similar rate and enzyme-resistant peptides were not observed in transgenic Bt chickpea lines. The unintended changes in the whole transcriptome profile of Bt chickpeas were surveyed using a homozygous transgenic line expressing a cry1Ac gene. The differentially expressed genes (DEGs) profiling confirmed a low (0.69%, log2fold change≥2) frequency of differentially expressed in the transgenic chickpea line. Only a small (34 upregulated) proportion of genes showed > 2 fold (P-value of 0.05, FDR of 0.05) change in their expression, while only 23 genes down-regulated by >2 fold. Furthermore, no transcripts for potential allergenic proteins were represented in the DEGs. Most of these genes appeared to be developmentally regulated or stress-related which was expected because absolute synchronous growth and development even under a controlled environment are challenging. A few upregulated (AT-hook motif nuclear-localized protein 17-like, probable inactive 2-oxoglutaratedependent dioxygenase AOP2, protein EXORDIUM-like) and down-regulated (histone H2B, gonadal, embryonic abundant protein VF30.1-like, fasciclin-like arabinogalactan protein 12) genes were subjected to qPCR. The qPCR data validated the fold change of the up-regulated (>2) and down-regulated (>-2) genes. Thus, the above data revealed no potential alterations in the nutritional equivalence or transcript profile of transgenic Bt chickpeas.ThesisItem Open Access A study on the role of exopolysaccharide in conferring acid tolerance in Bacillus sp.(AAU, Jorhat, 2018-01) Deka, Priyadarshini; Barooah, MadhumitaSoil bacteria have evolved various mechanisms to adapt to stress environmental conditions such as temperature, salinity, drought and low pH condition of soil. Among the several environmental stress conditions, soil acidity an important factor influencing physicochemical and biological properties of soil along with microbial diversity and crop production is an emerging issue of immense concern due to its wide spread distribution across the globe. Although low soil pH restricts the number and diversity of bacteria, it is known that some soil bacteria are able to thrive in such conditions having evolved various mechanisms including production of biofilm to circumvent acid stress. Bacterial exopolysaccharide (EPS) are high-molecular-weight complex polymers composed of sugar moieties that form the main component of the biofilm which aid the bacteria to colonize substrata. In the present study, a total of 28 isolates were identified and characterized as acid tolerant EPS producing bacteria among which, B. amyloliquefaciens p16 produce the highest EPS (219.96 μg/ml). A culture medium containing sucrose (3.5%) as carbon source with pH 5.0 and incubated for 24 hrs was optimal for maximum production of EPS. The HPLC analysis of monomeric units of EPS produced by B. amyloliquefaciens p16 revealed the abundance of galactose at pH 7.0 which however, changed to arabinose when shifted to acidic condition (pH to 5.0 and 4.5). The isolate B. amyloliquefaciens p16, significantly improved soil physical properties in terms of greater soil aggregation (80.59 mm diameter aggregates) and water holding capacity (53.90%) when inoculated into soil over the control (31 mm diameter aggregates and 18.21%, respectively). The differential expression of epsA and epsB, the first two genes of the eps operon showed a 7 and 9 fold increased expression in pH 5.0 compared to pH 7.0 respectively. Disruption of the epsB gene in B. amyloliquefaciens p16 using integration vector pMUTIN4 generated mutants that produced significantly lesser EPS (33.23 μg/ml) when compared to the WT (223.87 μg/ml). The generated mutant of B. amyloliquefaciens p16 lacking the wrinkled morphology had an extended lag phase of 24 hrs and was barely able to survive in acidic medium (pH 4.5) unlike that of the WT type. Soil inoculated with generated mutants formed smaller soil aggregates (42.41±1.70 mm) and had decreased water holding capacity (27.67±1.94%) compared to the WT (80.59± 0.22 mm and 53.90± 1.66%, respectively). This study indicates that EPS secreted by acid tolerant bacteria (B. amyloliquefaciens p16) imparts acid tolerance and also aids in improving the soil physical structure through increased soil aggregation and water holding capacity.ThesisItem Open Access Molecular characterization and nutritional equivalence evaluation of transgenic chickpea expressing either a cry1Ac or cry2Aa gen(AAU, Jorhat, 2019-10) Gupta, Rubi; Sarmah, Bidyut Kumariosafety assessment of transgenic chickpeas having B.thuringiensis genes for resistance to pod borers is a regulatory requirement and mandatory to document before releasing in the field. Therefore, Bt chickpea lines harbouring either a cry1Ac or cry2Aa gene were characterized for the presence and expression of the transgene in their advanced generations, biosafety assessments and transcript profile were studied. The homozygous lines were selected for comparative nutritional equivalence assay. Biochemical estimations of major nutritional components such as proximates, vitamins, minerals, fatty acids and anti nutrients confirmed that the Bt chickpeas lines are nutritionally equivalent to their non-transgenic counterparts and the seed composition is similar or within the range reported, previously. Seed protein quality was investigated by separating the proteins in PAGE and eluted proteins after mass spectrometry (MS) showed expected fractions of 11S legumin, 7S vicilin, and 2S albumin of chickpea storage proteins in the transgenic lines. The protein digestibility was assayed using the multi-enzyme system and transient pepsin hydrolysis to mimic simulated gastric fluid followed by trypsin hydrolysis to mimic simulated intestinal fluid. Total seed proteins of both the transgenic and nontransgenic lines were digested at a similar rate and enzyme-resistant peptides were not observed in transgenic Bt chickpea lines. The unintended changes in the whole transcriptome profile of Bt chickpeas were surveyed using a homozygous transgenic line expressing a cry1Ac gene. The differentially expressed genes (DEGs) profiling confirmed a low (0.69%, log2fold change≥2) frequency of differentially expressed in the transgenic chickpea line. Only a small (34 upregulated) proportion of genes showed > 2 fold (P-value of 0.05, FDR of 0.05) change in their expression, while only 23 genes down-regulated by >2 fold. Furthermore, no transcripts for potential allergenic proteins were represented in the DEGs. Most of these genes appeared to be developmentally regulated or stress-related which was expected because absolute synchronous growth and development even under a controlled environment are challenging. A few upregulated (AT-hook motif nuclear-localized protein 17-like, probable inactive 2-oxoglutaratedependent dioxygenase AOP2, protein EXORDIUM-like) and down-regulated (histone H2B, gonadal, embryonic abundant protein VF30.1-like, fasciclin-like arabinogalactan protein 12) genes were subjected to qPCR. The qPCR data validated the fold change of the up-regulated (>2) and down-regulated (>-2) genes. Thus, the above data revealed no potential alterations in the nutritional equivalence or transcript profile of transgenic Bt chickpeas.ThesisItem Open Access Cloning, Characterization and RNAi mediated silencing of gene encoding 1-deoxy-D-xylulose 5-phosphatereductoisome rase (DXR) in Centella asiatica(AAU, Jorhat, 2019-01) Sharma, Richa; Sen, PriyabrataCentella asiatica (L.) is one of the most valuable medicinal plants which belong to the family Apiaceae. The medicinal importance of this green leafy vegetable is known since prehistoric times. The pharmaceutical importance of this herb is due to the accumulation of large quantities of pentacyclic triterpenoid saponins, collectively known as centelloids synthesized by the isoprenoid biosynthesis pathway. Biosynthesis of triterpenoid in the plants proceeds via either of the two pathways, viz. Mevalonate (MVA) pathway (in the cytosol) or 2-C-methyl-Derythritol 4-phosphate (MEP) pathway (in plastid). In Centella, the pathway leading to the accumulation of triterpenoid is still not known. Thus, to know whether the MVA or MEP pathway or contribution of both has a role in the biosynthesis of triterpenoid, silencing the key regulatory enzyme gene using RNAi tool, of each of the pathway and then to analyze a metabolite is an efficient approach. In our lab, HMGR (a key enzyme of MVA pathway) RNAi construct has already been designed, confirmed by RT-PCR and validated by Agro-infiltration. 1-deoxy-D-xylulose-5- phosphate reductoisomerase (DXR) play a role in catalyzing the first committed step of the MEP pathway. The present study is the first step aimed to delineate the MEP pathway using RNAi silencing approach to knock down rate limiting 1-deoxy-Dxylulose- 5-phosphate reductoisomerase (DXR) enzyme. The full-length DXR gene sequence (JQ965955) of Centella has been characterized using in silico approach. CaDXR is a 1425bp ORF encoding a peptide of 474 amino acids and of molecular weight of 51.5 KDa. Multiple sequence comparison using MEGA tool showed the presence of two NADPH binding motif, two substrates binding motif, and one cleavage site motif. In this study, the 3-D structure of CaDXR was identified and validated along with this molecular dynamics simulation and finally docking with cofactor NADPH was done. The expression analysis suggests that CaDXR is differentially expressed in different tissues (with maximal expression in node and lowest in the roots). Our result suggests that nodes may be crucial to terpenoid biosynthesis in Centella asiatica. The RNAi-DXR construct was designed using the pHANNIBAL vector and subsequently cloned into a binary vector pART27. The binary vector pART27 containing RNAi-CaDXR construct was transformed into Agrobacterium strain AGL1. The transient analysis of the RNAi-CaDXR using semiquantitative RT-PCR confirmed the silencing of the endogenous DXR gene in Nicotiana and further confirmed in Centella asiatica. Thus, further incorporation of both the RNAi construct (HMGR and DXR) in transformed Centella shall shed light into the pathway that leads to the synthesis of principal secondary metabolites i.e centelloids.ThesisItem Open Access GENETIC STUDIES FOR IMPROVING YIELD UNDER DROUGHT STRESS ENVIRONMENTS IN RICE OF ASSAM(AAU, Jorhat, 2019-07) PARRAY, ROUF AHMAD; Baruah, Akhil RanjanDrought is a major limiting factor for rice under rainfed ecosystem in Assam. In this context, thirteen rice cultivars with varied level of drought tolerance were chosen from a set of 272 different rice genotypes based on a field experiment conducted during 2014-15 season under drought. The thirty days old seedlings of 13 cultivars were tested for extensive morpho-physiological, biochemical parameters, relative transcript accumulation and global gene expression using next generation sequencing (NGS) method, and data were recorded at fifth, tenth and fifteenth day of withholding water (DWW) in order to obtain detail trait based gene architecture and to improve high yielding variety of Assam using transcript dynamics. Among the physiological traits studied, Photosynthetic rate decreased with increasing water deficit, but the effect was less pronounced in Apo, Dumai and Tepi Dumai. The rate of transpiration decreased in all the cultivars under study. Moreover, the fall in transpiration rate was less in Apo. Water use efficiency (WUE) of rice plants was enhanced significantly under moisture stress at all the three periods of stress (5DWW, 10DWW, 15DWW) in Apo, Tepi Dumai and Dumai. Reduction in RWC was experienced across all genotypes but the decrease was less prominent in Apo, Dumai and Tepi Dumai. Drought stress condition led to increased proline content across genotypes as compared to irrigated condition. Apo, Tepi Dumai, Dumai and Kali Murali showed rapid increase compared to others. Increase in root length was observed across all cultivars with Apo being the longest followed by Dumai and Ranjit. Then, five drought responsive pathway genes (OsDREB2, OsNAC1, bZIP16, OsbZIP 23, OsbZIP72) were chosen to check the differential expression patern in the cultivars at the same data point as mentioned above. Expression profiling of OsDREB2 showed significant increase in gene expression with increase in drought stress in the case of Apo and Dumai. Significant expression of the OsNAC1 was found in Apo, Dumai at different time points of dehydration stress whereas expression of ARC 10372 was prominent in 15DWW. Apo showed significant difference in expression of bZIP16 under all the three stages of water stress whereas Dumai and Ranjit showed enhanced expression compared to other cultivars. Expression profile of OsbZIP23 showed significant accumulation of transcripts in Apo in all stages followed by Dumai. Significant expression of OsbZIP72 was observed in Apo at 10DWW and 15DWW followed by Ranjit and Dumai. Based on the results of morpho-physiological, biochemical and expression analysis, three cultivars, viz., Ranjit, Apo and Dumai were chosen to study the detailed transcriptome at only 10DWW. Transcriptome profile revealed highest mapped genes in Dumai followed by Ranjit and Apo, however, only 14.5% genes were in common. Ranjit was found to be more responsive to abiotic stimulus including water stress. Gene ontology (GO) suggested no significant change of pathway genes upto 10 DWW among the three cultivars. The transcriptome data were validated using five differentially expressed genes in these three cultivars along with a F4 mapping population. It revealed similar trend, suggesting the present transcriptome data set was in good fit. However, detail transcriptome study in vital plant parts at different stages under drought stress will throw more light about the interaction of pathway genes to adress the problem better.ThesisItem Open Access MAPPING AND DISSECTION OF GENETIC EFFECTS INTO QTLs FOR GRAIN YIELD UNDER DROUGHT IN ELITE RICE VARIETY OF ASSAM(AAU, Jorhat, 2017-01) VERMA, RAHUL KUMAR; Modi, M. K.Two traditional drought tolerant cultivars were crossed with Ranjit in the present study in order to identify QTLs and improved lines for various yield traits under drought stress. The allelic distribution of 45 SSR markers associated with major grain yield QTLs under drought stress were studied in 115 ahu rice cultivars. The cluster analysis distinguished cultivars into 2 major clusters. The drought tolerant cultivars (ARC10372 and Banglami) were grouped with tolerant check (Nagina22) and high yielding cultivars were grouped with susceptible check (Ranjit). A total of 110 polymorphic SSR markers were identified across the parents, Banglami and Ranjit. These SSR markers were used for segregation analysis in 180 F2 plants. Among 110 polymorphic SSR markers, 88 fitted the expected Mendelian segregation, whereas 22 (20.0%) significantly deviated from it (P<0.01). Only 89 SSR markers could be assigned to 12 linkage groups covering a total of 1628.7 cM of the rice genome. The F2:4 population consisting of 2460 F4 plants were evaluated for various yield traits under two hydrological conditions viz., irrigated control (non stress) and drought stress created in rainout shelter. The drought stress was imposed from panicle initiation to panicle emergence period (reproductive stage). A total of seven QTLs, viz., qNOT2.1 (number of tillers), qEBT6.2 (effective booting tillers), qPNL1.1, qPNL6.1 (panicle length), qNGP12.1 (number of grains per panicle), qNCP6.1 (number of chaff per panicle) and qGYP7.1 (grain yield), were identified under drought stress whereas, four QTLs viz., qEBT6.1 (effective booting tillers), qNCP4.1 (number of chaff per panicle), qSFP6.1 (spikelet fertility) and qGYP9.1 (grain yield), were identified under irrigated conditions. The cultivar ARC10372 was crossed with Ranjit and 180 F2 plants were raised. Among these, only 36 F2 plants carrying tolerant parent allele for the SSR markers RM431 and RM11943 associated with the major grain yield QTL (qDTY1.1) were selfed to raise F2:3 population. Only 10 F3 plants were selected on the basis of yield and root traits. These were selfed to raise F4 population. The F2:4 population consisting of 217 F4 plants were evaluated for various yield traits under drought stress and irrigated conditions. Two F2:4 lines (B-42, B-106) from ‘Banglami x Ranjit’ and one F2:4 line (A-78) from ‘ARC10372 x Ranjit’ were selected on the basis of improved yield and grain quality traits under drought stress. The selected plants may be used for the development of drought tolerant rice variety.ThesisItem Open Access STUDY ON MOLECULAR MECHANISM OF BRUCHID BEETLE (Callosobruchus chinensis) RESISTANCE IN BLACK GRAM (Vigna mungo L.)(AAU, Jorhat, 2017-01) Kakati, Indrani; Sarmah, Bidyut KumarBruchid beetles, (Callosobruchus spp.,) are a devastating stored grain pest of black gram. The interaction between bruchid and black gram genotype has not yet been demonstrated. In the present investigation, an attempt has been made to understand the molecular basis of resistance in a mild tolerant genotype (IC8219) of black gram through two molecular techniques, Suppression Subtractive Hybridization (SSH) library preparation and RNA Sequencing (RNASeq). This is the first report on elucidation of the molecular basis of defense during black gram-bruchid interaction. The changes related to generation of ROS and expression of defense related genes in a mild tolerant (IC8219 genotype) of black gram was studied after releasing bruchids. After 7 days of releasing bruchids, RNA from developing seeds of the pods oviposited by bruchids were collected. The generation of ROS was detected by using 3, 3’ diaminobenzidine (DAB) staining on the pods oviposited by bruchids. For suppression subtractive hybridization (SSH) the pods oviposited by bruchids were used as tester population, while RNA from seeds of control plants were used as driver population. A forward subtractive cDNA library was prepared from tester and driver population and subtracted cDNAs were cloned and transformed in JM109 competent cells. In all, 277 clones in an EST library were sequenced and analyzed. High quality ESTs (244) were submitted to the NCBI database (Acc. No. JZ917400-JZ917463). Based on CAP3 assembly, 134 genes were computationally annotated. The majority of the ESTs belonged to ‘Biological Process’ of gene ontology category. A total of 18 defense related genes were identified and were subjected to quantitative PCR analysis (qPCR). Of these 12 genes showed up-regulation in developing seeds. Few major defense genes like defensin, pathogenesis related protein (PR), lipoxygenase (LOX) showed high expression in the oviposited plants when compared with the non-oviposited plants. In order to obtain a greater representation of defense genes, de novo transcriptome assembly of RNA extracted from the pods oviposited by bruchids was also performed. RNASeq analysis revealed a total of 12,081 differentially expressed genes (DEGs) out of which 258 were up-regulated and 310 were down-regulated during black gram- bruchid interaction. In all, 20 defense related genes were identified of which 9 were represented both in the SSH library and RNASeq data. This is the first report on defense related gene expression study in developing seeds of black gram during upon egg laying by bruchid beetles.ThesisItem Open Access OPTIMISATION OF ETHNIC FERMENTED RICE BEER (XAJ) PRODUCTION OF ASSAM, INDIA(AAU, Jorhat, 2017-07) Keot, Jyotshna; Barooah, M.“Xaj”, the popular rice based alcoholic beverage is produced by the Ahom community of Assam using fermentation starter, Xaj pitha. The methodology of Xaj brewing is almost similar among the Ahom community residing in different localities of Assam, however, the concoction of the fermentation starters differ in terms of varieties and number of herbs or plant parts resulting in variation of the quality and acceptability of the final product. Fermentation starters are mixed cultures of fungi, yeasts and bacteria that are maintained on substrates like rice powder, supplemented with various herbs. Both fungi and yeasts present in the starter cultures are involved in rice based alcoholic beverage fermentation. Fungi are primarily involved in the initial liquefaction and saccharification process that breaks down the rice starch to fermentable sugars that is subsequently converted into alcohol by the yeasts. Based on traditional starter manufacturing method, defined fermentation starter culture was developed with the compatible microbial cultures consisting of fungus Amylomyces rouxii (NCBI accession number KP790015) Wickerhomomyces anomalus (NCBI accession number KX904346 ) and yeasts Saccharomyces cerevisiae (NCBI accession number KX904349) isolated from collected Xaj pitha samples. Selected plant extracts of Leucas aspera Spreng. Lygodium flexosum Vent. Polygonum strigosum L., Centella asiatica Urban and Alstonia scholaris (L.) R. Br. was added as representative herb for standard production of rice based alcoholic beverage based on their use value and frequency of use. Performance of defined starter culture in alcohol production and other biochemical properties of alcoholic beverage produced by defied starter culture were compared with that of Xaj produced using traditional starter culture, Xaj pitha. The rice based alcoholic beverage brewed using defined starter culture contained 10.23% (v/v) alcohol with 23.99% protein, 61.79% antioxidant activity, 0.48% acidity and a pH value of 3.79 after one month of fermentation whereas, the traditional starter culture was able to produce 12.3% alcohol, 22.27% protein, 60.23% antioxidant activity, 0.789% acidity and pH value of 3.33 after one month of fermentation. Fermentation was stabilised in the laboratory prepared rice based alcoholic beverage through the addition of sulphur dioxide (20ppm/L) and turbidity of standard alcoholic beverage was removed by filtration techniques that could be stored for 3 months without any major changes in the physical and chemical properties or taste. It also scored higher in Hedonic sensory attributes such as acidity, colour and overall acceptability. This study indicates the potential of defined starter to produce high quality standard Xaj pani which will pave the way to produce the product in commercial scale the near future.
