Chromium (Cr) (VI) has long been known as an environmental hazard that can be reduced from aqueous solutions through bioremediation by living cells. In this study, we investigated the efficiency of reduction and biosorption of Cr(VI) by chromate resistant bacteria isolated from tannery effluent. From 28 screened Cr(VI) resistant isolates, selected bacterial strain SH-1 was identified as Klebsiella sp. via 16S rRNA sequencing. In Luria–Bertani broth, the relative reduction level of Cr(VI) was 95%, but in tannery effluent, it was 63.08% after 72 h of incubation. The cell-free extract of SH-1 showed a 72.2% reduction of Cr(VI), which indicated a higher activity of Cr(VI) reducing enzyme than the control. Live and dead biomass of SH-1 adsorbed 51.25 mg and 29.03 mg Cr(VI) per gram of dry weight, respectively. Two adsorption isotherm models—Langmuir and Freundlich—were used for the illustration of Cr(VI) biosorption using SH-1 live biomass. Scanning electron microscopy (SEM) analysis showed an increased cell size of the treated biomass when compared to the controlled biomass, which supports the adsorption of reduced Cr on the biomass cell surface. Fourier-transform infrared analysis indicated that Cr(VI) had an effect on bacterial biomass, including quantitative and structural modifications. Moreover, the chickpea seed germination study showed beneficial environmental effects that suggest possible application of the isolate for the bioremediation of toxic Cr(VI).

Tomatoes (Solanum lycopersicum L.) have highmoisture content (93–95%), making them more vulnerable to various types of spoilage fungi. Numerous medicinal plants' essential oils are known to have antifungal properties that combat these spoilage fungi. Therefore, this study aimed to investigate the potential antifungal activity of essential oils from some indigenous plants in Bangladesh to prevent the fungal attack on tomatoes. Using potato dextrose agar medium, 4 species of spoilage fungi from tomatoes were identified. ITS (Internal transcribed spacer) region-specific sequencing was used to identify the fungal species as Aspergillus welwitschiae, Aspergillus tamari, Penicillium citrinum and Rhizopus arrhizus. Assessment on antifungal activity was conducted for four essential oils extracted from plants: turmeric leaf (Curcuma longa), patchouli (Pogestemon cablin), palmarosa (Cymbopogon martini) and lemongrass (Cymbopogon citratus). The GC-MS method was used to analyze these essential oils to ascertain their chemical content. A pathogenicity test determined the severity and % of rot on tomatoes. A. welwitschiae caused the most severe spoilage (80%) after 21 days, while R. arrhizus damaged 26% of the tomatoes within 5 days. The minimal fungicidal concentration (MFC) and minimal inhibitory concentration (MIC) of the essential oils were determined after analysis. Lemongrass oil fully suppressed the growth of all the isolates at a concentration of 12 ????l/ml. Finally, the essential oils of palmarosa and lemongrass may be used as a preventative measure against tomato fungal rot.