Growth-enhanced Performance by Pleurotus ostreatus Cultivated on Salon Effluent and Spent Calcium-carbide Amended Substrates

Aims: To investigate the growth response of Pleurotus ostreatus, a wood-rotting fungus, to different growth substrates [Sawdust (SD), dry banana leaves (BL) and a combination of both BL and SD (BLSD)] amended with waste [salon effluent (SE) and spent calcium-carbide (SC)]. Place and duration of study: Department of Plant and Ecological Studies, University of Calabar, Cross River State, Nigeria, between May 2015 and August 2015. Methodology: Amendments were applied to growth substrates at different levels of concentration as follows: 0 ml and 0 g, 5 ml and 5 g, 10 ml and 10 g, 15 ml and 15 g per kg substrate. Mature mushrooms were harvested and assessed on the following parameters; number of fruit bodies, fresh weight, dry weight, length of stipe, girth of stipe, pileus area using conventional method. Results: Number of fruitbodies, fresh weight, dry weight and stipe length increased with increase in concentration of additives. Best performances of these growth parameters were obtained at 15 g/kg and 15 ml/kg concentration. The highest number of fruitbodies (with a peak mean value of 28.42 fruitbodies at 15 g/kg concentration), highest value of fresh weight and dry weight were observed in SD. The longest stipe length, largest stipe girth and pileus area were observed in BLSD, though it exhibited least performances in other growth parameters. BLSD amended with salon effluent produced mushrooms with the largest pileus area (with a peak mean value of 53.8 cm2 at 15ml concentration) compared to the other substrates. Conclusion: This study reveals that all growth parameters of P. ostreatus assessed were positively influenced by all the levels of amendments on the substrates used in this study. Therefore, these wastes could be used to increase the yield of P. ostreatus and possibly remediate sites polluted by these wastes.

Changes in Vegetative and Reproductive Growth and Quality Parameters of Strawberry (Fragaria × ananassa Duch.) cv. Chandler Grown at Different Substrates

Growth substrates (polyester wool, rice husk, and wheat straw), along with soil as control treatment, were compared for vegetative growth, yield, and quality of strawberry cv. Chandler. All growth substrates tested showed good results in terms of growth rate as compared with control. Strawberry plants grown in polyester wool showed the highest (89.50%) survival rate as compared to rice husk (70.50%), wheat straw (64.63%), and control (67.56%). Moreover, a significant increase was observed among number of flowers, fruits, and yield in plants grown in polyester wool. Besides, a significant high amount of total soluble solids (TSS) (12.38 ºBrix), titratable acidity (TA) (1.21%), ash (0.72%), vitamin C (37.39 mg/100 g), total carotenoids (3.90 µg/100 g), and total anthocyanins (3.47 cyanidine-3-glucoside/100 g) was recorded in fruits grown in polyester wool as compared to control. From these results, it can be concluded that the use of polyester wool as a growth substrate for strawberries can give higher yield and better fruit quality.

Co-inducible catabolism of 1-naphthol via synergistic regulation of the initial hydroxylase genes in Sphingobium sp. strain B2

1-Naphthol, a widely used raw material for organic synthesis, is also a well-known organic pollutant. Due to its high toxicity, 1-naphthol is rarely used by microorganisms as the sole carbon source for growth. In this study, catabolism of 1-naphthol by Sphingobium sp. strain B2 was found to be greatly enhanced by additional supplementation with primary carbon sources (e.g., glucose, maltose and sucrose), and 1-naphthol was even used as the carbon source for growth when strain B2 cells had been pre-induced by both 1-naphthol and glucose. A distinct two-component flavin-dependent monooxygenase NdcA1A2 was found to be responsible for the initial hydroxylation of 1-naphthol to 1,2-dihydroxynaphthalene, a more toxic compound. Transcriptional levels of ndcA1A2 genes were significantly up-regulated when strain B2 cells were cultured with both 1-naphthol and glucose as compared to cells cultured with sole 1-naphthol or glucose. Two transcriptional regulators, the activator NdcS and the inhibitor NdcR were found to play key roles in the synergistic regulation of the transcription of the 1-naphthol initial catabolic genes ndcA1A2. Importance Co-metabolism is a widely observed phenomenon, especially in the field of microbial catabolism of highly toxic xenobiotics. However, the mechanisms of co-metabolism are ambiguous and the roles of the obligately co-existing growth substrates remain largely unknown. In this study, we revealed that the roles of the co-existing primary carbon sources (e.g. glucose) in the enhanced catabolism of the toxic compound 1-naphthol in Sphingobium sp. strain B2 was not solely because they were used as growth substrates to support cell growth, but more importantly they acted as “co-inducers” to interact with two transcriptional regulators, the activator NdcS and the inhibitor NdcR, to synergistically regulate the transcription of the 1-naphthol initial catabolic genes ndcA1A2. Our findings provide new insights into the co-metabolic mechanism of highly toxic compounds in microorganisms.

The Phytotoxicity of Microencapsulated Peppermint Oil on Maize (Zea mays L.) Depending on the Type of Growth Substrate and Maize Cultivar

Microencapsulated peppermint (Mentha × piperita L.) essential oil (MPEO) is a prospective botanical herbicide. A hypothesis was formulated that the type of growth substrate (vermiculite, silty clay loam or sandy loam soil) and the cultivar affect the phytotoxic potential of MPEO on maize (Zea mays L.). The pot experiments assessed the effect of varying doses of MPEO or maltodextrin, a carrier of microcapsules, mixed with the growth substrates, on maize’s emergence and early growth. The morphological analyses were supported by the measurements of total phenolics in the second leaf and roots. The MPEO revealed phytotoxic effects on maize in all of the growth substrates already at a low dose (36.0 g m−2), displayed by the delays of maize emergence, reduced growth, and biomass accumulation. Maltodextrin also caused significant reductions in biomass of maize roots. In conclusion, maize is susceptible to substrate-applied MPEO, the type of substrate and the cultivar of maize, can modify this effect to a limited extent.