Isolation and characterization of bacteria associated with the rhizosphere of halophytes (Salsola stocksii and Atriplex amnicola) for production of hydrolytic enzymes

Abstract

Microbes from hypersaline environments are useful in biotechnology as sources of novel enzymes and proteins. The current study aimed to characterize halophilic bacteria from the rhizosphere of halophytes (Salsola stocksii and Atriplex amnicola), nonrhizospheric, and brine lake-bank soils collected from Khewra Salt Mine and screening of these bacterial strains for industrially important enzymes. A total of 45 bacterial isolates from the rhizosphere of Salsola, 38 isolates from Atriplex, 24 isolates from non-rhizospheric, and 25 isolates from lake-bank soils were identified by using 16S rRNA gene analysis. Phylogenetic analysis showed that bacterial strains belonging to Bacillus, Halobacillus, and Kocuria were dominant in the rhizosphere of halophytes (Salsola and Atriplex), and Halobacillus and Halomonas were dominating genera from non-rhizospheric and lake-bank soils. Mostly identified strains were moderately halophilic bacteria with optimum growth at 1.5-3.0 M salt concentrations. Most of the bacterial exhibited lipase, protease, cellulase, amylase, gelatinase, and catalase activities. Halophilic and halotolerant Bacilli (AT2RP4, HL1RS13, NRS4HaP9, and LK3HaP7) identified in this study showed optimum lipase, protease, cellulase, and amylase activities at 1.0-1.5 M NaCl concentration, pH 7-8, and temperature 37°C. These results indicated that halophilic and halotolerant bacteria can be used for bioconversion of organic compounds to useful products under extreme conditions.

Streptomyces sp. strain TOR3209: a rhizosphere bacterium promoting growth of tomato by affecting the rhizosphere microbial community

“…Then 1.0 g of seedling roots were put in 20 mL 0.85% saline solution and were shaken at 200 rpm/min for 30 min to release the rhizosphere soil for obtaining a microbial suspension 2 7 . Then the roots were surface sterilized and grinded with 5 mL of physiological saline as the original extraction of root endophytes 28 , 29 . The original solutions of rhizosphere microbes and root endophytes were diluted to 10 –4 and every dilution was plated onto NA4 plate (0.1 mL per plate), which contained (g/L): K 2 HPO 4, 1.0; KH 2 PO 4, 1.0; Sodium pyruvate, 0.5; peptone, 10.0; beef extract, 3.0; glucose, 3.0; NaCl, 5.0; agar, 15.0 and yeast, extract 1.0.…”

Comparative Study of the Rhizosphere and Root Endosphere Microbiomes of Cholistan Desert Plants

“…Recent studies about rhizosphere microbiome of desert halophytes revealed a high portion of halophilic bacteria as compared to rhizosphere microbiome of salinity sensitive plants ( Marasco et al, 2016 ; Tian and Zhang, 2017 ). A number of halophilic bacterial genera including Bacillus, Halomonas, Halobacillus, Oceanobacillus, Marinobacter, Marinococcus , and Nesterenkonia have been identified from the rhizosphere and roots of halophytes and xerophytes ( Ramadoss et al, 2013 ; Zhao et al, 2016 ; Etesami and Maheshwari, 2018 ; Mukhtar et al, 2019 ).…”

“…PGPRs also provide plant protection against fungal and bacterial diseases by production of a variety of antifungal and antibacterial compounds ( Bulgarelli et al, 2013 ). Halophiles are able to produce different industrially important enzymes such as protease, lipase, amylase, laccase, xylanase, and cellulase with polyextremophilic properties ( Kumar et al, 2012 ; Mukhtar et al, 2019 ). Halophilic enzymes have potential for different industrial applications including textile, paper and pulp, pharmaceutical, baking, and detergent industries ( Liszka et al, 2012 ; Mukhtar et al, 2019 ).…”

“…Halophiles are able to produce different industrially important enzymes such as protease, lipase, amylase, laccase, xylanase, and cellulase with polyextremophilic properties ( Kumar et al, 2012 ; Mukhtar et al, 2019 ). Halophilic enzymes have potential for different industrial applications including textile, paper and pulp, pharmaceutical, baking, and detergent industries ( Liszka et al, 2012 ; Mukhtar et al, 2019 ). Halophilic bacteria can also be used for bioremediation of a variety of hazardous compounds in saline and arid environments ( Liszka et al, 2012 ; Castillo-Carvajal et al, 2014 ; Tian and Gao, 2014 ).…”

Effects of Enterobacter cloacae HG-1 on the Nitrogen-Fixing Community Structure of Wheat Rhizosphere Soil and on Salt Tolerance

“…Salinity is one of the major abiotic stresses, with a total of 3% of the world’s land mass being affected by salinity ( Mukhtar et al., 2018 ). Global increase in soil salinization constitutes a most devastating environmental threat for crop yield and food quality ( Asrar et al., 2017 ).…”