scholarly journals Bio-Floc Technology: Prospects & Challenges in Fish Farming of Nepal

2020 ◽  
Vol 8 (2) ◽  
pp. 140-145
Author(s):  
Prajina Neupane ◽  
Madhusudhan Adhikari ◽  
Manita Kumari Thapa ◽  
Astha Kiran Pandeya
Keyword(s):  
Water Quality ◽  
Carbon Source ◽  
Nutrient Recycling ◽  
Bacterial Biomass ◽  
Fish Farming ◽  
High Carbon ◽  
Carbon Nitrogen Ratio ◽  
Nitrogen Ratio ◽  
Technical Manpower ◽  
Blue Revolution

Bio-floc technology is the blue revolution in aquaculture & new technique of enhancing water quality & utilizing feed wastes in the aquaculture system. It follows the concept of conversion of ammonium in addition to organic nitrogenous wastes into bacterial biomass in where heterotrophic bacterial growth is stimulated & nitrogen uptake through the production of microbial proteins is promoted by the addition of carbohydrates to the pond. Nitrogen generated by uneaten feed and excreta of cultured organisms is converted into proteinaceous feed available for those same organisms. This technique recycles nutrients & nitrogenous wastes by maintaining a high carbon: nitrogen ratio and provides essential & higher quality nutrition to the shrimps & fishes in achieving fast growth, lesser FCR & possibility to prevent diseases. Water requirement in BFT is extremely less & it is advantageous than the conventional system where there is continuous water & nutrient recycling, lower FCR. On the other hand, many challenges are existing in practicing bio-floc in Nepal as it requires frequent pond monitoring by the technical manpower. The choice of carbon source should be made wisely and correctly as the performance of fish and water quality in the bio-floc ponds depend highly upon carbon source. Further, vitamins required for fish may not be produced by microbes thus needed to identify them and supply through the feed. However, the practice of bio-floc technology will be proven worth for farmers in Nepal. Int. J. Appl. Sci. Biotechnol. Vol 8(2): 140-145  

scholarly journals Wax ester production in nitrogen-rich conditions by metabolically engineered Acinetobacter baylyi ADP1

2019 ◽  
Author(s):  
Jin Luo ◽  
Elena Efimova ◽  
Pauli Losoi ◽  
Ville Santala ◽  
Suvi Santala
Keyword(s):  
Metabolic Engineering ◽  
Isocitrate Lyase ◽  
Fatty Acyl ◽  
Wax Esters ◽  
Wax Ester ◽  
High Carbon ◽  
Acinetobacter Baylyi ◽  
Storage Lipids ◽  
Carbon Nitrogen Ratio ◽  
Nitrogen Ratio

AbstractMetabolic engineering can be used as a powerful tool to redirect cell resources towards product synthesis, also in conditions that are not optimal. An example of a synthesis pathway strongly dependent on external conditions is the production of storage lipids, which typically requires high carbon/nitrogen ratio. Acinetobacter baylyi ADP1 is known for its ability to produce industrially interesting storage lipids, namely wax esters (WEs). Here, we engineered the central carbon metabolism of A. baylyi ADP1 by deletion of the gene aceA encoding for isocitrate lyase in order to allow redirection of carbon towards WEs. The production was further enhanced by overexpression of fatty acyl-CoA reductase Acr1 in the wax ester production pathway. This strategy led to 3-fold improvement in yield (0.075 g/g glucose) and 3.15-fold improvement in titer (1.82 g/L) and productivity (0.038 g/L/h) by a simple one-stage batch cultivation with glucose as carbon source. The engineered strain accumulated up to 27% WEs of cell dry weight. The titer and cellular WE content are the highest reported to date among microbes. We further showed that the engineering strategy alleviated the inherent requirement for high carbon/nitrogen ratio and demonstrated the production of wax esters using nitrogen-rich substrates including casamino acids, yeast extract and baker’s yeast hydrolysate, which support biomass production but not WE production in wild-type cells. The study demonstrates the power of metabolic engineering in overcoming natural limitations in the production of storage lipids.

Environmental significance of atrazine in aqueous systems and its removal by biological processes: an overview

2013 ◽  
Vol 8 (2) ◽  
pp. 159-178 ◽  
Keyword(s):  
Drinking Water ◽  
Ground Water ◽  
Water Environment ◽  
Biological Processes ◽  
Biological Degradation ◽  
Environmental Significance ◽  
Carbon And Nitrogen ◽  
Carbon Nitrogen Ratio ◽  
Nitrogen Ratio ◽  
Living Organisms

Atrazine, a chlorinated s-triazine group of herbicide is one of the most widely used pesticides in the World. Due to its extensive use, long half-life and various toxic properties, it has very high environmental significance. Up to 22 mg l-1 of atrazine was found in ground water whereas permissible limit of atrazine is in ppb level in drinking water. As per Indian standard there should not be any pesticide present in drinking water. Among many other treatment processes available, Incineration, adsorption, chemical treatment, phytoremediation and biodegradation are the most commonly used ones. Biological degradation of atrazine depends upon various factors like the operating environment, external carbon and nitrogen sources, carbon/ nitrogen ratio (C/N), water content and the bacterial strain. Although, general atrazine degradation pathways are available, the specific pathways in specific conditions are not yet clearly defined. In this paper extensive review has been made on the occurrence of atrazine in surface and ground water bodies, probable sources and causes of its occurrence in water environment, the toxicity of atrazine on various living organisms and its removal by biological processes.

scholarly journals Effects of Organic Fertilizer on Bok Choy Growth and Quality in Hydroponic Cultures

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 491
Author(s):  
Kazuki Kano ◽  
Hiroaki Kitazawa ◽  
Keitaro Suzuki ◽  
Ani Widiastuti ◽  
Hiromitsu Odani ◽  
...  
Keyword(s):  
Plant Root ◽  
Oxygen Deficiency ◽  
Organic Fertilizer ◽  
Corn Steep Liquor ◽  
Ascorbic Acid Content ◽  
Growth And Yield ◽  
Significant Difference ◽  
Carbon Nitrogen Ratio ◽  
Nitrogen Ratio ◽  
Steep Liquor

Effects of corn steep liquor (organic fertilizer, OF) and conventional chemical fertilizer (CF) on the growth and yield of bok choy (Brassica rapa var. chinensis) in summer and autumn hydroponic growing systems were compared. When OF and CF were applied with the same amount of total nitrogen in summer cultivation, there was no significant difference between yields; however, the growth rate in OF was slower than in CF. When OF was applied with twice the amount of nitrogen in CF (OF2), bok choy growth and yield were significantly inhibited in summer cultivation, likely owing to dissolved oxygen deficiency and different rates of nitrification and nitrogen absorbance by the plant root. Although the contents of potassium, calcium, and magnesium in bok choy showed no difference among the three treatments in both cultivation seasons, the carbon/nitrogen ratio tended to be higher in OF and OF2 than in CF. Lower nitric acid and higher ascorbic acid content was found in OF and OF2 than in CF. Overall, our results suggest that a comparable yield is expected by using the same nitrogen amount with a conventional recipe of chemical fertilization in autumn cultivation. However, further improvement of hydroponic management is needed in summer cultivation.

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