New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton

Jeffrey, S. W.; Humphrey, G. F.

doi:10.1016/s0015-3796(17)30778-3

Cited by 4,430 publications

(2,104 citation statements)

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“…The supernatant was transferred to a 10 mm quartz cuvette, and spectrophotometric readings were taken at four different wavelengths, 630 nm, 647 nm, 664 nm and 750 nm. The chlorophyll a concentration was calculated using the Jeffrey and Humphrey method (Jeffrey and Humphrey, 1975) and expressed in mg L -1 (APHA, 1999).…”

Section: Methodsmentioning

confidence: 99%

Toxic concentrations of metronidazole to Microcystis protocystis

et al. 2014

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Antimicrobials are among the most commonly used drugs and have become a class of contaminants with great environmental importance. Metronidazole is an antimicrobial used for the therapeutic management of several human diseases. The toxicity of antimicrobials on aquatic species may affect sensitive microorganisms and reduce metabolic processes. Cyanobacteria is a group of organisms that are of great ecological importance in aquatic environments. Studies indicate that cyanobacteria are very sensitive to some antimicrobials. Therefore, it is necessary to evaluate the effects of metronidazole contamination on phytoplankton. The aim of this study was to investigate the effects of metronidazole on the growth of the cyanobacterium Microcystis protocystis and to evaluate the stability of this antimicrobial agent in the culture medium over a period of 96 hours. M. protocystis was resistant to growth inhibition by metronidazole. The EC50 of this antimicrobial for M. protocystis was 117.3 mg L -1 . Under the growth inhibition test conditions, neither a significant change in the MNZ concentration nor the presence of drug metabolites or degradation products was observed. These results indicate low cellular uptake of the antimicrobial agent and its persistence in the culture medium.Keywords: antimicrobials, toxicity, metronidazole, cyanobacterium, Microcystis protocystis. Concentrações tóxicas de metronidazol para Microcystis protocystis ResumoAntimicrobianos estão entre os fármacos mais usados e tem se tornado uma classe emergente de contaminantes com grande importância ambiental. A toxicidade dos antimicrobianos sobre as espécies aquáticas podem afetar microrganismos sensíveis e reduzir seus processos metabólicos. O Metronidazol é um antimicrobiano usado para o manejo terapêutico de várias doenças humanas. Cyanobacteria é um grupo de organismos de grande importância ecológica no ambiente aquático. O estudo visou investigar os efeitos do metronidazol-MNZ sobre o crescimento da cianobactéria Microcystis protocystis e avaliar a persistência do antimicrobiano no meio de cultivo durante 96h. A M. protocystis mostrou-se resistente à inibição de crescimento pelo MNZ. A EC 50% do MNZ para a espécie foi 117,3 mg L -1 . Nas condições do teste de inibição de crescimento não foi observada variação significativa da concentração de MNZ nem a presença de metabólitos ou produtos de degradação do fármaco, indicando baixa captação celular do antimicrobiano e sua persistência no meio de cultivo.Palavras chave: antimicrobiano, toxicidade, metronidazol, cianobactéria, Microcystis protocystis.

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Section: Methodsmentioning

confidence: 99%

Toxic concentrations of metronidazole to Microcystis protocystis

et al. 2014

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“…Clorophyll a concentration was determined using the 100% acetone extraction method of Jeffrey and Humphrey (1975). The total lipid method used was adapted from Kates and Volcani (1966).…”

Section: Methodsmentioning

confidence: 99%

Limits to productivity of the algaPleurochrysis carterae(Haptophyta) grown in outdoor raceway ponds

Moheimani

Borowitzka

2006

Biotech & Bioengineering

117

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This study examined the effects of oxygen concentration, pond temperature and irradiance on productivity and CaCO 3 formation of the coccolith-forming alga, Pleurochrysis carterae CCMP647 grown in semi-continuous culture in outdoor raceway ponds. During the day the oxygen content of the pond increases markedly and P. carterae photosynthesis is inhibited by these high O 2 concentrations with the inhibition increasing with increasing temperature. The high irradiance outdoors presents less of a problem to photosynthesis and productivity as the algae can acclimate well to high irradiances over a period of several weeks. Pond depth also effects productivity and this effect varies with season. During autumn, productivities were highest at depths of 13 to 16 cm, and decreased when the depth was increased. During summer productivity was much lower at 13 cm pond depth and increased when the depth was increased to 16, 18 and 21 cm. Heating the ponds in the morning by approximately 3 to 58C improves productivity by 11%-21%, presumably because this allows the algae to photosynthesise faster in the conditions of low [O 2 ] which occur in the early morning.

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“…Chlorophyll a contents were determined according to Jeffrey and Humphrey (1975) with 90% (v/v) acetone extracts. Nitrate and phosphate concentrations in cultures were determined, respectively, by the method of Collos et al (1999) and Harrison (1988).…”

Section: General Analysesmentioning

confidence: 99%