Abstract
As knowledge of sulphur oxidising bacterial communities in mangrove sediments is very sparse and sulphur oxidizers have wide application such as in treatment of wastewater containing high sulphate levels which causes unwanted H 2 S production by sulfate reducing bacteria (SRB), oxidation of elemental sulphur to plant available sulphate for plant growth promotion, bio leaching, biocontroling agent etc. Hence, in the present study an attempt has been made to explore the diversity of sulphur oxidizing bacteria from mangroves of Mahanadi delta, Odisha to evaluate their biotechnological potential. Two sulphur oxidising bacteria (SOB-7and SOB-8) were isolated from mangrove soils of Mahanadi river delta, based on the change of colour of the thiosulphate broth medium from purple to colour less by reducing the pH. Based on morphological, biochemical and 16S rRNA gene sequencing the two strains (SOB-7) and (SOB-8) were identified as Klebsiella sp., and Micrococcus sp. respectively. The gene bank accession number of the strains are KR632644 (SOB-7) and KR632643 (SOB-8). The strain Klebsiella sp. and Micrococcus sp showed sulphate ion production ability of 243 mg/ml and 240 mg/ml respectively with decrease in pH from 7.0 to 4.0. Among these two isolates, SOB-8 showed higher sulphide oxidase production ability (126.83 U/ml) than the isolate, SOB-7 (126.0 U/ml). Maximum sulphide oxidase by both the strains were obtained at temperature 45℃, peptone as nitrogen source, thiosulphate concentration of 10 mg/ml. pH 9.0 for the isolate SOB-8 whereas pH 7.0 for the isolate, SOB-7. Partially purified enzyme of both the isolate showed higher activity at same substrate concentration of 1.5mg/ml, but varies with pH and temperature.
Highlights
Sulphur is the fourth major plant nutrient after N, P and K, and is one of the sixteen nutrient elements which are essential for the growth and development of plants, especially in the agricultural crop production [1]
Sulphide oxidase is the key enzyme produced by these microorganisms, responsible for sulphide ions oxidation [6]
Two sulphur oxidising bacteria were isolated from mangrove soil sample of Mahanadi delta, Odisha using sulphur oxidizer-agar medium
Summary
Sulphur is the fourth major plant nutrient after N, P and K, and is one of the sixteen nutrient elements which are essential for the growth and development of plants, especially in the agricultural crop production [1]. The majority of sulphur taken up by plant roots is in the form of sulphate (SO4), which undergoes a series of transformations prior to its incorporation into the original compounds [3]. The soil microbial biomass is the key driving force behind all sulphur transformation. Biological oxidation of hydrogen sulphide to sulphate is one of the major challenges of the global sulphur cycle [4]. Sulphur oxidizing bacteria present in soil oxidize various sulphur compounds and improve soil fertility. It results in the formation of sulphate, which can be used by plants, while the acidity produced by oxidation helps to solubilise plant nutrients [5]. Sulphide oxidase is the key enzyme produced by these microorganisms, responsible for sulphide ions oxidation [6]
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