Are fish fed with cyanobacteria safe, nutritious and delicious? A laboratory study

Abstract

Toxic cyanobacterial blooms, which produce cyclic heptapeptide toxins known as microcystins, are worldwide environmental problems. On the other hand, the cyanobacteria protein (30–50%) has been recommended as substitute protein for aquaculture. The present laboratory study verified the feasibility of cyanobacteria protein substitution and risk assessment. Goldfish were fed diets supplemented lyophilised cyanobacteria powder for 16 weeks with the various doses: 0% (control), 10%, 20%, 30% and 40%. Low doses (10% and 20%) promoted growth whereas high doses (30% and 40%) inhibited growth. In cyanobacteria treated fish, the proximate composition of ash, crude fat content and crude protein content decreased in 16 weeks; the saturated fatty acid (SFA) content significantly increased; the n-3 polyunsaturated fatty acid content, collagen content and muscle pH significantly decreased; cooking loss percents increased significantly. Muscle fiber diameter and myofibril length were negatively correlation. Additionally, flavour compounds (e.g., amino acids, nucleotides, organic acids and carnosine) changed significantly in the treated fish, and odour compounds geosmin and 2-methylisoborneol increased significantly. The estimated daily intake (EDI) of microcystins in muscle was close to or exceeded the World Health Organization (WHO) tolerable daily intake (TDI), representing a great health risk. Cyanobacterie is not feasible for protein sources use in aquaculture.

Effects of toxic cyanobacteria and ammonia on flesh quality of blunt snout bream (Megalobrama amblycephala)

“…Because the pattern and quantity of essential amino acids strictly determines the nutritional value of protein food for humans, the decreased essential amino acids (including phenylalanine, histidine, isoleucine, leucine, lysine, methionine and threonine) and total essential amino acids suggested a declined nutritional value of blunt snout bream fillet caused by dietary toxic cyanobacteria and ammonia exposure. A similar result was achieved by Liang et al who reported significantly lower levels in total amino acids contents and almost all essential amino acids when goldfish were fed diets contained a high dose (30% and 40%) of cyanobacteria for 16 weeks.…”

“…Feed ingredients were showed in Table . Based on the toxic cyanobacteria powder contents in our previous study, two isonitrogenous and isoenergetic diets were prepared. The control diet (TCP0) contained no toxic cyanobacteria powder, whereas the experimental diet (TCP30) contained 30% toxic cyanobacteria powder.…”

“…Therefore, we aimed to investigate whether flesh quality is affected when blunt snout bream are exposed to such polluted water conditions. The result of our previous studies indicated that dietary toxic cyanobacteria powder had an adverse impact on the flesh quality of goldfish ( Carassius auratus ), including nutritional values, flavour and odour . However, limited information is currently available on the influence of ammonia on fish flesh quality.…”

Changes in Phytoplankton and Water Quality during Sustainable Restoration of an Urban Lake Used for Recreation and Water Supply

“…Water blooms caused by cyanobacteria are unfavorable especially for lakes used for water supply and for recreational purposes. They can pose a health threat owing to the potential production of toxins, which can lead to serious health problems [54][55][56][57]. An efficient method for removing cyanotoxins from water is essential [58].…”

Cloning and Expression of Genes for Biodegrading Nodularin by Sphingopyxis sp. USTB-05

“…Until now, more than 100 analogues of MCs and about nine analogues of NODs [10,11,12] have been described in the literature. Toxic cyanobacteria frequently result in human health hazards and wildlife fatalities [13,14,15,16,17,18,19,20]. Nodularia spumigena was firstly reported in the literature as the toxic cyanobacterium for livestock [21].…”