The harmful effect of salinity stress on crops needs to be mitigated. Therefore, the application of microbial inoculum in combination with nanomaterials and methyl salicylate was investigated. Initially, different seeds were exposed to salinity levels treated with variable microbial treatments using different modes of applications. The microbial treatments included application of cyanobacterial strain Cyanothece sp. and the rhizobacterium Enterobacter cloacae, alone or in combination with one another, and a final treatment using combined microbial inoculum supplied with methyl salicylate. Later, different nanomaterials were used, namely, graphene, graphene oxide, and carbon nanotubes in combination with biofertilizers on the highest salinity level. The nanomaterial with microbial treatment and methyl salicylate were applied partly as a mixture in soil and partly as capsules. Results showed that salinity stress had a drastic inhibitory effect on growth parameters, especially at −5 MPa level. Nonetheless, the microbial treatments significantly alleviated the deleterious effect of salinity stress, especially when combined with methyl salicylate. When the nanomaterials were added to biofertilizers at highest salinity level, the inhibitory effect of salinity was mostly alleviated. Smart use of synergistic biofertilizers alongside the right nanomaterial, both encapsulated and in soil, would allow for mitigation and alleviation of inhibitory effect of salinity.

Chlorella vulgaris from Al-Ahsa, KSA was proved to be an active silver and gold nanoparticle producer. Nanogold and nanosilver particles were characterized using UV-visible spectroscopy, Fourier-transform infrared spectroscopy, and scanning electronmicroscopy. Both nanoparticles were used in the antimicrobial bioassay. The two nanoparticles showed antibacterial activities, with the silver nanoparticles being the most effective. To investigate the argumentative nature of their biosynthesis (i.e., whether it is a biotic or abiotic process), we isolated total ribonucleic acid RNA as an indicator of vitality. RNA was completely absent in samples taken after one week of incubation with silver nitrate and even after one or two days. However, successful extraction was only achievable in samples taken after incubation for one and four hours with silver nitrate. Most importantly, the gel image showed recognizable shearing of the nucleic acid after 4 h as compared to the control. An assumption can be drawn that the synthesis of nanoparticles may start biotically by the action of enzyme(s) and abiotically by action of reducing entities. Nonetheless, with prolonged incubation, excessive nanoparticle accumulation can be deadly. Hence, their synthesis continues abiotically. From the RNA banding profile, we suggest that nanosilver production starts both biotically and abiotically in the first few hours of incubation and then continues abiotically. Nanosilver particles proved to have more of an antimicrobial impact than nanogold and hence are recommended for different applications as antibacterial agents.

In this work, carbon-based nanomaterials including; carbon nanotubes (CNT) and graphene were combined with biofertilisers and tested their impact on germination of Hordeum vulgare. The interaction between nanomaterials and biofertilisers was analysed. Scanning electron microscopy (SEM) images revealed that the surface of algal cells was covered with carbon nanomaterials including graphene and CNTs. Raman studies showed the characteristic band of graphene, CNTs and Algal cells. The combination of carbon nanomaterials with biofertilizers resulted in significantly better growth than with nanomaterials individually. To prepare a more effective superfertiliser, zinc ferrites (ZnFe2O4) nanoparticles were added to the nanomaterials-biofertilisers combination. These zinc ferrites nanofertilisers had a size ranging from 8–12 nm and were prepared by co-precipitation method and used at two different doses. The results showed that the growth parameters were increased most significantly with addition of 0.25 ml of ZnFe2O4 nanoparticles. Increasing the dose caused a less increase in growth parameters. These results indicated that increase in growth parameters was dose-dependent. These results demonstrated a great promise for novel formulation of superfertiliser that significantly enhanced plant growth without pollution or excessive use of harmful chemicals for better food security and environmental sustainability.