Cyanobacteria were among the pioneer organisms of the early earth. They first colonized bare rock and had a strong ability to proliferate in infertile substrates, such as volcanic ash, desert sand, and rock. Cyanobacteria store enormous amounts of essential nutrients and metabolites within their cytoplasm. Those that grow in arid lands can be a very potent source of organic matter and nutrients that can be used to counteract desertification. In this study, we explored the potentiality of cyanobacterial strains collected from several regions of Asia (7 strains), Africa (3 strains), and Japan (6 strains). Some of the soils had salinity levels greater than 5 dS m-1 and an alkaline pH of 8.3-9.2. Cyanobacterial strains were screened for their potential to survive in such arid soils by quantifying individual salinity tolerance, ability to fix N2 in a medium containing 0.1M NaCl, and rates of photosynthesis and growth. The inoculation effects on the chemical properties of Alashan soils of Inner Mongolia (China) were evaluated using AL-S and Tateyama cyanobacterial strains. The soil pH of the surface and subsurface layers indicated that these strains can decrease pH to levels that are conducive to plant growth. These cyanobacterial strains have potential as anti-desertification agents for the bioreclamation of arid soils.
The ability of soil microorganisms to decolorize Reactive Red 141, an industrial textile dye used commonly in Southeast Asia, including Thailand, was analyzed. Incubation experiments showed that the dye was decolorized under a static anoxic condition of liquid medium inoculated with soil microorganisms, while it was not decolorized in a shaking aerobic condition. Fourteen isolated bacteria that decolorize the dye were identified and found to belong to Gram-positive bacteria, such as Bacillus, and Gram-negative bacteria, such as Stenotrophomonas. Attenuated total reflectance fourier transform infrared (ATR-FTIR) analysis suggested that the intermediate products of degradation of the dye were naphthalene derivatives and other smaller compounds produced by oxidative cleavage of the dye, irrespective of the difference of the strains. Together with the variety of the phylogenetic locations of the isolated strains, this suggested that the reaction is catalyzed by non-specific enzyme(s) under an anoxic condition.