Study of microbial isolation from soil of leguminous plants collected from pattoki

Background: Soil isthe region where most of the physical, biological and biochemical reactions related to decomposition of organic matter, degradation, cycling of nutrients, mineral and metal transformation occur.The soil environment with diverse microbial population responsible for nitrogen fixation, decomposition and mineral transformation which aid in maintaining a sustainable soil environment.All nutrients that plants absorb have to pass a region of intense interactions betweenroots, microorganisms and animals, termed the rhizosphere.Leguminous plants belong to family Fabaceaeand includes peas, lentils, beans, chickpeas and soybeans etcSome groups of bacteria grow in roots of legumes which aid in crop rotation. The study aims are to isolation, identification and characterization of nitrogen fixing bacteria. Determine prevalence of high number of Rhizobium in soil samples of leguminous plants.
Methods:The observational and prospective study was conducted on soil samples collected from Pattoki pea, soybean, chickpeas, lentil and beans field in the period of two days and examined from 1st March to 30thMay 2019. For prevention of contamination, glass wares (such as conical flask, test tube, pipette, petri dish etc) was washed and sterilized before taking bacterial sample.Media are the synthetic mixtures of bacto-peptone 10g, NaCl 5g, Yeast extract Powder 0.5g in a liter of distilled water, Agar powder of 105g was added in 100 ml for solidification of liquid medium. These were used for culturing the bacteria in glass- tubes and in petri dishes.
Results:E.coli, Rhizobium, Pseudomonas and Proteus specie of bacteria were identified in soil samples. E.coli obtained in highest quantity (35%) then Rhizobium (33%), Pseudomonas (28%)and Proteus species (4%) as shown in graph.Their presence confirm by Catalase, Oxidase, Voges- Proskauer and Indole tests. The biochemical tests performed on the isolates (Rhizobium, E.coli, Proteus and Pseudomonas)showed that most were positive for Catalase, Oxidase, Voges – Proskauer and Indole tests. Sugar tests positive during isolation and characterization of Rhizobium meliloti on most of leguminous plant roots. All identified species are motile and gram negative rods in nature. Pseudomonas and Rhizobium are aerobic while Proteus and E.coli are facultativeanaerobe and aerobe respectively. Colony morphology of E. coli on blood agar was slightly convex, grey and moist with hemolytic property of some strains. Proteusshowed swarming over entire surface and the ripples on water on blood agar. The colonies of Pseudomonaswere observed to slightly opaque colony while showed large, flat, spreading colonies with clear zones of hemolysis. Rhizobium with mucoid colony characteristics has morphology onblood agar was non hemolytic and on MecConkey agar was non lactose fermenting. Complex microbial and faunal interactions with plant roots accompanied and shaped the evolution of land plants. In future we recommend to use these beneficial bacteria instead of organic or synthetic fertilizers.
Conclusion:Rhizobium is an important microorganism for the environment because of its nitrogen-fixing ability when in symbiotic relationship with plants (mainly legumes). This study confirmed that the root nodules of leguminous plant harbour the nitrogen-fixing bacterium- Rhizobium. It also showed that leguminous plants when inoculated with Rhizobium isolates perform better. This organism will greatly enhance agricultural production, if they are often used to inoculate legume plants, thereby reducing the environmental threat of synthetic nitrogen fertilizers.