Effect of water bloom-forming cyanobacterial bio-substances on the growth of submerged macrophyte Ceratophyllum oryzetorum Kom.

The different forms of cyanobacterial bio-substances on the growth and photosynthetic activity of submerged macrophyte Ceratophyllum oryzetorum Kom was investigated in present study. Results showed that all kinds of cyanobacterial bio-substances ould enhance the growth of C. oryzetorum Kom. differently. Compared with the control, the plant length of C. oryzelorum could be increased by all forms of bio-substanees, in which the dry algal material has the strongest effect, while the decomposed material has the lowest. The fresh weight of C. oryzetorum also could be promoted by all kinds of algal bio-substanees, in which the dry algal material and the fresh algal material almost have the same obvious effect, and the decomposed algal material has the lowest, while in control, the fresh weight firstly increased, and then decreased. All forms of cyanobacerial material could promote the increase of branches in C. oryzetorum, in which the fresh algal material has the strongest effect and the dry and decomposed materials lower, while in control, the branches increased also less than the algal material treated groups. The photosynthetic activity expressed by chlorophyll fluorescence suggested that the (try algal material treated C. oryzetorum had the highest activity, and the fresh algae treated one lower, and the decomposed algae and the control treated ones were the lowest. In conclusion, the different forms of cyanobacterial bio-substances could supply nutrients or growth promoters for C. oryzetorum to grow, and at the same time, other growth inhibiters might exist to inhibit the growth of C. oryzetoritm. Factors of promoting and inhibiting worked together, thus resulted in the different promoting effects by different forms of cyanobacterial bio-substances to the growth in C. oryzetorum

Nostoc sphaeroides Kutzing, an excellent candidate producer for CELSS

Some phytoplankton can be regarded as possible candidates in the establishment of Controlled Ecological Life Support System (CELSS) for some intrinsic characteristics, the first characteristic is that they should grow rapidly, secondly, they should be able to endure some stress factors and develop some corresponding adaptive strategies; also it is very important that they could provide food rich in nutritious protein and vitamins for the crew; the last but not the least is they can also fulfill the other main functions of CELSS, including supplying oxygen, removing carbon dioxide and recycling the metabolic waste. According to these characteristics, Nostoc sphaeroides, a potential healthy food in China, was selected as the potential producer in CELSS. It was found that the oxygen average evolution rate of this algae is about 150 mu mol O(2) mg(-1) h(-1), and the size of them are ranged from 2 to 20 mm. Also it can be cultured with high population density, which indicated that the potential productivity of Nostoc sphaeroides is higher than other algae in limited volume. We measured the nutrient contents of the cyanobacterium and concluded it was a good food for the crew. Based on above advantages, Nostoc sphaeroides was assumed to a suitable phytoplankton for the establishment of Controlled Ecological Life Support System. We plan to develop suitable bioreactor with the cyanobacterium for supplying oxygen and food in future space missions. Crown copyright (C) 2011 Published by Elsevier Ltd. on behalf of COSPAR. All rights reserved

DYNAMICS OF CHLOROPHYLL FLUORESCENCE AND ECO-MORPHOLOGICAL PROPERTIES OF Microcystis BLOOM IN MEILIANG BAY OF LAKE TAIHU, CHINA

Eutrophication has become a serious concern in many lakes, resulting in cyanobacterial blooms. Some variations of physiological activity and eco-morphological property in Microcystis bloom, especially in field experiment, are currently less studied. This study aimed to describe what changes of physiological activity and eco-morphological property had happened, and identify what is the key factor resulting in the decline of Microcystis bloom. The chlorophyll fluorescence, buoyancy and colony sizes of Microcystis and variation of physico-chemical data in the Meiliang Bay estuary of Lake Taihu, China, was investigated everyday from July 18, 2009 to July 29, 2009. In field investigation, F(v)/F(m) Phi(PSII) and qP can regarded as effective indicators to evaluated physiological activity and the growth state of Microcystis bloom. We found on sunny days, photoinhibition occurred 2 hours later than that on cloudy days, but photodamage indicated by unrecoverable decreasing F(v)/F(m), was observed after exposure to high light for a long time. While on cloudy days, the photoinhibition of Microcystis seemly occurred more easily and recovered quickly at weak light. Controlling experiment showed that nutrient depletion could lead to decreased buoyancy, dis-aggregated colonies and dropping photosynthesis of Microcystis. Based on these results of high light, rich DO, a negative correlation between DO and F(v)/F(m), and a lagged photoinhibition on sunny days, we inferred Mehler's reaction was a protective mechanism of photosystem for a short time, but results in photodamage when exposure is long enough. In all, we conclude the long-term illumination of high light companied with nutrient depletion caused by rapid growth of Microcystis might be the main reasons for the bloom decline

Comparison of the photosynthetic characteristics of two developmental stages in Nostoc sphaeroides kutzing (Cyanophyta)

The photosynthetic activities between two main developmental stages, colony and hormogonium, of the edible cyanobacterium Nostoc sphaeroides Kutzing, were compared. Hormogonia have a higher content of chlorophyll than that of colonies. It showed that the ratios of phycocyain (PC), allophycocyain (APC) and phycoerythrocyanin (PEC) in hormogonia and colonies were different. The room temperature chlorophyll fluorescence, 77 K chlorophyll fluorescence measurements of PS I and PS H activities all showed that colony has higher photosynthetic competence than hormogonia. Hormogonia had a higher respiration rate than colony, while their maximum photosynthetic oxygen evolution rates were very close. The responses of hormogonia and colonies to high light illuminations also were different. Both of their oxygen evolution rates decreased quickly with the prolonged high light illumination, but hormogonia can keep relatively higher PS II activity (F-v/F-m) than that of colonies. The results suggested that colony was photosynthetically more competent than hormogonia. while the ability of hormogonia to tolerate high light illumination was higher than that of colony