Abstract:MicroRNA, a short non-coding RNA chain, plays important roles in post-transcription regulations by targeting gene 3'UTR through sequence complementary principle. Previous researches showed that microRNAs play important roles in heart development process. Heart development of the Antarctic icefish (Chionodraco hamatus) shows compensatory physiological enlargements due to the lack of functional red blood cells in the body. Previous studies suggested that microRNAs specifically expressed in the C. hamatus heart may be associated with icefish compensatory physiological enlargement. In this study, according to the highly expressed miR-210-5p, we studied the heart development functional mechanism of miR-210-5p by using zebrafish microinjection and gene's target prediction. The results showed that overexpression of miR-210-5p in 72hdf zebrafish embryos could affect zebrafish heart development, characterized by cardiac malformations such as pericardial edema. QRT-PCR analysis showed that overexpression of miR-210-5p in zebrafish downregulated heart development marker genes including bmp4, smad1, gata6, tbx2b. Western blot analysis found that the protein expression levels of BMP4, BMP2, SMAD1, GATA6 and TBX2B were downregulated. According to the bioinformatics prediction and GFP fluorescence analysis, we found tbx20 may be a target of miR-210-5p. Therefore, we speculated that miR-210-5p might inhibit tbx20 gene expression and might suppress heart development of C. hamatus through bmp/smad pathway.

Abstract:In order to improve the quality of larvae of Macrobrachium rosenbergii,growth performance of progeny of 5 spawning batches(Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ) were checked by one-way completely randomized design. The results indicated that, the number of larvae increased with spawning number increasing, and the first three spawning batches had higher survival rate. The ranks of AGR were Ⅲ > Ⅱ > Ⅴ > Ⅳ > Ⅰ, Ⅱ,Ⅲ spawning batches showed obvious growth advantage after AGR comparison by LSD. Survival rate of Ⅰbatch was significantly higher than other four batches. Variation coefficient of body weight of first three spawning batches was lower than last two. It showed the figure of first three spawning batches were more tidy. The quantity of female shrimp atⅠ, Ⅱ, Ⅳ, Ⅴ batch is greater than males after 60 days feeding, but the sex ratio (♀/♂) of Ⅲ meets 1:1. Microsatellite markers were used to analyze the genetic diversity and genetic differentiation of 5 spawning batches. The results showed that:polymorphism information content (PIC) of 5 spawning batches in order was Ⅱ(0.586 3) > Ⅰ(0.583 5) > Ⅴ(0.560 2) > Ⅲ(0.560 1) > Ⅳ(0.555 8). These all were highly polymorphic. The longest genetic distance(0.017 0) was between Ⅰ batch and Ⅴbatch, the shortest genetic distance(0.000 3) was between Ⅳ batch and Ⅴbatch. The genetic relationships among each offspring batch were very close. It indicated that there were no significant differences of genetic structure among 5 spawning batches.

Abstract:The full-length cDNA sequence of glutamine synthetase from black tiger shrimps (Penaeus monodon)(denoted as PmGS) was obtained by high throughput transcriptome sequencing and RACE. On this basis, the expressions of the PmGS gene in different tissues and in hepatopancreas and gill during ammonia nitrogen stress were detected by fluorescence-quantitative real time PCR. The cDNA of PmGS was 1 420 bp,the length of the open reading frame (ORF) was 1 086 bp encoding a polypeptide of 361 amino acids,a 5'UTR of 40 bp and a 3'UTR of 294 bp. The molecular mass of the deduced amino acid (aa) sequence was 40.423kDa with an estimated pI of 6.19. And there was a poly A with 27 bp. Like other animal GSs,the structure of the PmGS protein consisted of a Glnsynt_C domain.There were eight phosphorylation sites and two glycosylation sites in this protein. Sequence alignment analysis and phylogenetic analysis showed that the PmGS with the GS of Fenneropenaeus chinensiss shared a similarity of 99.45%. Analysis of the tissue expression pattern of the PmGS showed that the PmGS mRNA was expressed in all tested tissues,including lymphoid tissue,ovary,eyestalk nerve,brain, stomach,muscle,intestines,thoracic nerve,hepatopancreas and gill. With the highest levels in lymphoid tissue, the second level in gill and the lowest level in thoracic ganglia. The expressions of the PmGS gene in hepatopancreas and gill significantly differ from the control group (P<0.05), and the expression profiles differed between hepatopancreas and gill. The result shows that PmGS might play an important role in shrimp ammonia metabolism and be involved in responses to acute ammonia stress.

Abstract:Morphological and SRAP markers were used to analyze the phylogenetic relationship and genetic diversity of eight populations of Moerella iridescens in Zhejiang Province, especially focusing on Yueqing bay. The populations in Yueqing, Wenling and Taizhou had the similar morphologies, but they had more difference with the populations in Ningbo and Zhoushan. The genetic diversity of population in Yueqing was higher than that in Zhoushan or Ningbo. All populations collected from Yueqing were clustered together, showing that they had smaller genetic distance and higher genetic similarity. The similarity in both morphological and SRAP data reflects the geographical relationship among the eight populations. It should be noted that aquaculture population of M. iridescens collected from Yueqing was more similar with that from Ningbo, not with those from Yueqing, reminding us to avoid possible germplasm hybrid of M. iridescens in Yueqing bay.

Abstract:To investigate the relationship between growth properties and thermal and high salt tolerance in Sinonovacula constricta, We have established and obtained 27 families with different growth performance of Sinonovacula constricta in 2014 based on the excellent group from Leqing Bay. Growth traits of different families were recorded in the first three months:Five families showed superior growth rate, seventeen families showed medium growth rate and five families showed inferior growth. After the next three months, five superior and inferior families were obtained respectively. In the preliminary experiment, the semi-lethal temperature and salinity of Sinonovacula constricta are 36.5℃ and 35.8 respectively. With the control group of group breeding Sinonovacula constricta, each families were cultivated in the environment of normal salinity, 36.5℃ water or normal temperature, 35.8 salinity respectively. To conclude, the survival rate of superior families was higher than the disadvantage families under the conditions of semi-lethal temperature and salinity and there was a significant difference in heat tolerance and salt tolerance among the different families studied(P<0.05) by multiple comparison and variance analysis. The strongest family were higher than the worst family by 74% and 50% respectively in upper thermal and salt tolerance.

Abstract:The new varieties of "Shenfu No. 1" and "Shenfu No. 2" and the traditional cultivar of Pyropia haitanensis were cultivated at the same sea for testing their high-temperature-resistance in the study. The results showed that the blades of the traditional cultivar rotted away due to the water temperature higher by 1 to 2℃ as compared to that of the normal year after cultivation of P. haitanensis at sea. However, the varieties "Shenfu No. 1" and "Shenfu No. 2" maintained the normal color and morphology of blades and higher growth rate, and good yield and quality, even if cultivated at the same sea area. The results indicated that the new varieties "Shenfu No.1" and " Shenfu No.2" had the advantages of high-temperature-resistance and higher growth speed than the traditional cultivar. The new varieties "Shenfu No. 1" and "Shenfu No.2" had a great potential to be used as a substitute for the traditional cultivar in the future.

Abstract:Off-flavor in cultured fish has been causing more and more attention. To learn composition and concentration of off-flavor substances in tilapia culture waters under different culture patterns, this paper monitored concentration of geosmin and 2-methylisoborneol, two main odor substances in water by using purge and trap pre-treatment with gas chromatography-mass spectrometry (P&T-GC-MS). 7 farms including one reservoir and 6 intensive culture ponds were sampled in Wenchang, Hainan province, as well as 15 farms including 3 reservoirs, 6 intensive ponds and 6 vertically-integrated ponds (pig and tilapia) in Maoming, Guangdong province in May, August and October, 2013. The results showed that 2-MIB is the main odor substance in the waters, and the concentration in water ranges from 0-65.61 μg/L, while concentration of GSM in water ranges from 0-11.77 μg/L. In the three culture patterns, the concentration of the two odor substances in reservoirs is the lowest, followed by intensive ponds, whereas the integrated ponds have the highest. There are significant differences between two culture modes (P<0.05). There is no significant difference among culture months and sites. The results indicate that different culture patterns could affect the odor components in water. Sources of odor substances from vertically-integrated ponds are more complex, which are easy to produce off-flavor.

Abstract:The paper detected 17 biochemistry indices of the 39 healthy captive hatching larval green turtles (1.5-2.5 years old), six healthy adult green turtles (10-20 years old) and 3 wild turtles using the Beckman AU5800 and TNI BECKMAN Access 2 to analyze. The results showed that there was large difference between wild and captive ones on aspartate aminotransferase (P=0.002), albumin (P=0.015), alkaline phosphatase (P=0.010), glutamic pyruvic transaminase (P=0.010), etc. The biochemistry indexes presented no difference in captive green turtles between different ages and different sexes except for alkaline phosphatase. Alkaline phosphatase and age showed a negative correlation. Compared with the research results of others' and the experiment's wild green turtles, the indexes of wild individuals had great difference which could not be regarded as the reference for health indicators. This study established blood biochemistry reference values of captive green turtles in cardiac, liver and renal functions. This provides a reference for the wild green turtles' blood biochemistry research and established a basis for the early diagnosis and disease prevention of captive green turtles.

Abstract:In order to reveal the characteristics of bacterial community in the cyanobacterial blooming pond, the water samples in the cyanobacterial blooming ponds and the control ponds were collected from four aquaculture farms located in Guangdong, Yunnan and Guizhou Provinces, respectively. Both the physicochemical factors and biological indicators were analyzed. By applying polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique,the differences in bacterial community structure in these water bodies were found. The bacterial community diversity in aquaculture water were analyzed according to the abundance of PCR-DGGE fingerprint bands, and conducted an unweighted pair group method with arithmetic mean (UPGMA) cluster analysis on the bacterial community structure in the water body. The results indicated that the PO₄-P content was significantly higher in cyanobacterial blooming pond than that in the control pond (P<0.01).Linear regression analysis revealed a positive correlation between PO₄-P and the content of chlorophyll a (Chl.a), which represents the degree of cyanobacterial blooming (R²=0.869, P<0.01).The analysis of physicochemical factors in combination with the redundancy analysis (RDA) in bacterial community indicated a close relationship between PO₄-P and bacterial community in aquaculture water. While no significant difference in bacterial community diversity was seen between cyanobacterial blooming pond and control pond (P>0.05), significant differences in bacterial community structure between the two ponds existed. Further sequencing analysis revealed that the characteristic bacteria in the cyanobacterial blooming pond was Flexibacter, which might play a role in algal pyrolysis. The Synechococcsus content was significantly lower in the cyanobacterial blooming pond than that in the control pond. This reduced Synechococcsus content might be related to the inhibition of Synechococcsus growth by the substantial blooming of Microcystis.

Abstract:Effects of different concentrations of carbonate alkalinities on oxygen consumption rate, ammonia excretion rate, plasma ammonia content as well as relative gene expression profile of Rh family in gill of Leuciscus waleckii Dybowski fish were studied using closed water flow respiration measurement chamber. Oxygen consumption rate and ammonia excretion rate were significantly inhibited in different alkalinity conditions in comparison with those in control, and the lowest values of them were found at C_A90, which indicated C_A90 may be the alkalinity limit for this species. Contrarily, the plasma ammonia content showed the opposite trend, first increasing, then decreasing, and peaked at C_A90. No significant difference was found for plasma ammonia content when C_A ranged from 0 to 50 mm, indicating this species has evolved to have specific ammonia excretion mechanism and thus helps to maintain the low level of toxic ammonia form. Quantitative real-time PCR showed that Rhcg1 and Rhcg2 out of the four tested genes in Rh family may play an important role in the process of ammonia excretion under high alkaline stress. Energy metabolism (O:N) study found that L. waleckii Dybowski did not consume too much energy to satisfy the energy needs within tolerance range (C_A0-70); however, when the environmental alkalinity was between 90 and 110, the body fat and carbohydrates became the main energy sources to reduce protein consumption, which in turn decreased the poisonous ammonia excretion. This study served to elucidate the ammonia excretion strategy and possible physiological and molecular mechanism of ammonia excretion in L. waleckii Dybowski under high alkaline stress and it may provide evidence for aquaculturing L. waleckii Dybowski species in different carbonate alkaline water bodies.

Abstract:The objective of the present study was to evaluate the effects of feeding broad bean on haematology indexes and redox balance of grass carp (Ctenopharyngodon idellus). Grass carp with body weight of (936.7±6.1)g were fed formula feed (control group) and broad bean (broad bean group), and then were sampled for measuring haematological indexes and redox balance indexes at various time points. Results showed that the amounts of white blood cells and lymphocyte, hemoglobin level, average corpuscular volume and average corpuscular hemoglobin are affected by both diets and feeding period. At the 12^th week, fish fed broad bean had a significantly lower amounts of white blood cells, lymphocytes, red blood cells and lower hemoglobin level than control fish (P<0.05). The hepatopancreas CAT activity at the 4^th week, the gills superoxide dismutase (SOD) activity and the muscle malondialdehyde (MDA) content at the 8^th week, the hepatopancreas SOD activity, the SOD, catalase(CAT) activities of muscle and gills and the MDA contents in hepatopancreas and muscle at the 12^th week, were all significantly increased by feeding broad bean (P<0.05), when compared with control group. In terms of tissue glutathione level, fish fed broad bean had lower level of reduced glutathione (GSH) and lower ratio of GSH/GSSG (oxidized glutathione) in gills and muscle at the 4^th week, lower GSH level, lower ratios of GSH/GSSG in hepatopancreas and gills, and lower GSH/GSSG ratio in muscle at the 8^th week than those of control group (P<0.05). At the 12^th week, the GSH level and ratios of GSH/GSSG in gills of fish fed broad bean were also significantly lower than those of control group (P<0.05). In conclusion, feeding broad bean could produce cumulative damage to haematological indexes and redox balance of grass carp, and some measures should be taken to promote the anti-oxidation property of the fish.

Abstract:The comparisons have been made between Squaliobarbus curriculus and Cirhirnus mrigala to clarify the suitability as food fish for Mandarin fish based on the biological characteristics and the feasibility studies were conducted on Squaliobarbus curriculus as replacement of Cirhirnus mrigala for mandarin fish farming. The results showed that Cirhirnus mrigala and Squaliobarbus curriculus had similar feeding habit, both belong to low-age mature and poly-spawning type fish, wider adaptability to salinity, and stronger resistance against low oxygen than Mandarin fish. Squaliobarbus curriculus has three times spawning a year with large fecundity, with easy sources of broodstocks. The methods and facilities for fish breeding are similar to conventional carps and Mandarin fish, the success of the induced breeding is easily achieved. Good production can be easily obtained by one-time sufficient stocking and multi-times catches, also with low cost. Therefore, these two types of fishes are both available with good characters as fish food. But in the Yangtze River basin, Squaliobarbus curriculus can well survive in the winter, while Cirhirnus mrigala can not. Moreover, Squaliobarbus curriculus has longer breeding and growing periods and higher production. Therefore it is appropriate to use Squaliobarbus curriculus for Mandarin fish food instead of Cirhirnus mrigala. This provides good opportunity for Mandarin fish culture, especially in the off-season production. It is also a reference to improve the farming systems for Mandarin fish.

Abstract:Due to its ability to form dense mats in small water bodies (such as rivers and landscape ponds), duckweeds are often considered as nuisance plants in some freshwaters. As an attempt to find a new effective management tool, this study set out with the aim of assessing the influence of seven Chinese herb extracts addition upon the growth of duckweeds (Soirodela polyrhiza). The results show that Coptis chinensis Franch, Euphorbia humifusa willd and Alisma plantago-aquatica extracts have significant growth inhibition on Soirodela polyrhiza. Coptis chinensis extract showed statistically significant effect on Soirodela polyrhiza frond growth with few new fronds found after 96 h. Euphorbia humifusa extract increased Soirodela polyrhiza biomass slower than that of the control. Accounting for 69% of control was found after plants received the extract 96 h. Alisma plantago-aquatica extract showed statistically significant effect on Soirodela polyrhiza chlorophyll. Compared with control, higher than 55% chlorophyll decrease was found after plants received the extract 96h. In conclusion, Chinese herb extracts can inhibit the growth of extract and effectively controlled Soirodela polyrhiza growth. This study suggests that using Chinese herb extract as an herbicide to control the blooms of duckweeds is workable.

Abstract:A 12-day experiment was conducted to compare the differences of Gracilaria blodgettii and Gracilaria bailinae from decay process.Results showed:(1) At end of experiment, G. blodgettii body weight lost 22.52% at 10 days while G.bailinae lost 8.5% at 8 days,stating they were at early decomposition process.The decomposition process presented two obvious phases,the decomposition rate of G. blodgettii was greater than G.bailinae.Furthermore, the physiological responses of algae were changing,G.blodgettii malonaldehyde (MDA) content showed higher than G.bailinae, but in contrast of the activity of superoxide dismutase (SOD),indicating that the memberane system of G.blodgettii suffered serious damage,and weakened in antioxidant capacity.(2) The percentage of nitrogen decomposed was higher than that of phosphrous,and the release of phosphorus lagged behind nitrogen.Besides, the order of nitrogen amount realeased from the algae was G.blodgettii and G.bailinae,the order of total phosphorus amount released was G.bailinae and G.blodgettii. But G.blodgettii total nitrogen and total phosphorus in the water was greater than that of G.bailinae.(3) G.blodgettii moisture content and C/N initial value was 95% and 52.11, G.bailinae moisture content and C/N initial value was 91% and 24.01,after which the values fell.In conclusion, G.blodgettii had a longer decay time, the higher algae body weightlessness rate and decomposition rate,besides, G.blodgettii antioxidant ability was weak,but total nitrogen released more. So G.blodgettii suffered more serious decomposition than G.bailinae. Therefore, we inferred that algae nitrogen and phosphrous concentration, the ability of antioxidant,algae moisture content and C/N ratio may be the factor which caused two gracilaria genera algae differences in early decomposition and nutrient releasing.

Abstract:The macroalgal blooms have occurred in the Yellow Sea every year since 2007, resulting in environmental damage and huge economic losses. According to the monitor data in the field, we found the green tide disappeared in the Qingdao Sea area. In this paper, we used the satellite remote sensing, marine surveillance and laboratory experiments to explain the drifting process, the dynamic change of coverage areas and the floating macroalgal physiological characteristics along the coast of Qingdao in 2014. The results showed that the green tide began to affect Qingdao coast at the late May; from mid-June to the early July, the impacted area of the macroalgal blooms expanded quickly and reached its peak value; afterwards, the blooms decreased gradually. In-situ mesocosm experiments showed that the growth rate of algae biomass was about 2%/d, the floating algae were of light green or yellow, partly white. Most of the Ulva species had the structure of sacs, some were tubular and pleated. The intervals of the macroalgal cells increased and a part of them presented granulation. The fluorescence activity of Ulva algae in the Qingdao sea area was less than 0.52, and the chlorophyll content was low, about 0.3 mg/g. This study showed that the floating Ulva macroalgae were in a stage of degradation.

Abstract:As the use of clean energy increasingly gains attention, China's offshore wind power industry has been developing rapidly in recent years. However, the underwater noise from the wind power station has not been studied in our country while the noise from human activities as an environmental issue has attracted much concern around the world in the last few years. In this study, we collected the operational noise data from the offshore wind turbines in the vicinity of the Shanghai Donghai Bridge and studied the characteristics of different wind turbines. We compared the noise data from different depths of water, as well as compared the data collected by using different measurement methods. The results show that the noise data from each single wind turbine shares the characteristics of low frequency and low sound pressure level:the main frequency range is within 400 Hz and the sound pressure level is between 81 dB and 101 dB. The characteristics of underwater noise from different depths are basically the same when seawater flowing speed keeps constant, but when the speed increased, some of the main frequency lost or shifted. The fixed-point method we used can measure any location we set, but the measurement time is limited. Drift method can measure at any time but the measurement line is limited.

Abstract:Large cage net (purse net) is a vital way to utilize the sea water resources of deep sea.Net damage detecting is the basic condition for its normal running. Low cost and high reliable frame-type AUV is a feasible technical method to conduct the function. Based on the requirement of technique, cost and convenient operation, this paper proposes a cage net spiraling detection strategy of frame-type AUV, sets up the motion model and computes the driving force.The control method and working conditions relative with water current etc. were obtained. According to the model analysis, this paper designs the frame-type AUV structure, develops the 3 degree of freedom control hard/software and underwater video supervising/microwave communication system with 1.5 km working distance. The equipment developed is verified in Xiangshangang Bay of Zhejiang Province, China. The results show the system can acquire clear cage net pictures within 0.9 m and 1.5 m distance in spring and neap tide respectively from underwater when the flow velocity is less than 0.8 m/s, and its damage situation can be easily judged, which meets the practical requirement and provides stable foundation for large scale application.

Abstract:Currently,the main way to construct marine ranching and reform habitat is to build up underlying reefs,however the whole ocean water space can't be fully used in these aspects,such as generating upwelling of nutrient substance,bait field, spawning ground and biological chain,which do not maximize its efficiency.To solve this problem,based on sea conditions and biological characteristics in offshore waters in the East China Sea,a kind of upper-middle-class floating reef is developed that can cooperate with bottom reefs.Proceed from improving flow field and keeping volume unchanged,the flexible floating reef with four layers frame was designed,then its buoyancy force,gravity and capability of resisting waves were calibrated and calculated.The technical scheme of anchor system and the method of monitoring its applying effect underwater were determined.Three reefs were placed in marine ranching of Xiangshan Bay to test their practical effect.The test results show that the designed reef can effectively improve the regional flow field.It can keep tensile state in axial and has a tilt less than 20 degree in strong tidal current.The data from several investigations and video monitoring system show that the upper-middle-class flexible floating reefs can cooperate with the bottom reefs.Some fish appeared stably around after the floating reefs were placed for 2 months.The effect is satisfactory.

Abstract:The status of Chinese fishing fleet of South China Sea area (Guangdong, Gangxi and Hainan) is analyzed in this paper according to China Fisheries Statistic Yearbook and the fisheries resources status of South China Sea, including the total number, tonnage and main engine power of the fleet, also the size distribution of main engine power and fishing gears. In 2013, the total number of the fishing fleet in this area was 81 647, with a total tonnage of 1 566 000 tons,including 78 671 motorized vessels with 3 823 000 kW. More than 75% of the motorized fishing vessels in this area were less than 12 m LOA and 44.1 kW, which increased rapidly in 1980s and 1990s, and has kept stable in the last 10 years. The number of big-size vessels in this area with engine power more than 441 kW is very small, and increasing very slow to less than 0.6 percent of the total motorized fishing vessels, while the number of medium-size vessel with engine power 44.1-441 kW is stable. In terms of fishing gear, the fishing vessels are dominated by gill net (63.5%), followed by trawl (11.5%), purse seine (7%), and line (7%). Totally speaking, the fishing capacity of this area is too high, and the number of small-sized vessels is too big, while the composition of fishing gear is unreasonable. Suggestions of this paper are:further reduce the fishing fleet, and give priority to reduction of small-sized vessels, while moderately keep the number of large-sized vessels. The vessels fishing by trawl and gill net should be reduced substantially,while vessels fishing by line should increase, and purse seine fishing and deep-water trawling should be encouraged.

Abstract:Based on the surface water samples collected around the South Orkney Islands in the austral summer 2012, using the AAS (Atomic Absorption Spectrometry), this paper analyzes the concentration and distribution of typical trace elements (Cu, Pb, Zn, and Fe) of surface water. The results show that the ranges of Cu, Pb, Zn, Fe are 0.033-0.121 mg/L, 0.414-1.478 mg/L,0.008-0.083 mg/L, and 0.255-0.454 mg/L, respectively. And the average concentrations of Cu, Pb, Zn and Fe are 0.059 mg/L, 0.908 mg/L, 0.037 mg/L, 0.351 mg/L respectively, and that the concentration of Fe and Zn had increasing trend from west to east. And also it needed to be testified for this result why the concentration of these trace elements in this study was higher than that in other papers. But this result can provide basic data for the marine environment information database in the Southern Ocean and further help to study marine biogeochemistry in the Southern Ocean.

Abstract:The role of sigB, a major transcriptional regulator of stress response genes of Listeria monocytogenes, was assessed in biofilm formation of wild type strain (WaX12) and sigB deletion mutant (WaX12-ΔsigB) as affected by temperatures (4℃, 15℃, 25℃ and 37℃), pH values (4, 5, 6 and 7) and NaCl concentrations (0.5%, 2.5%, 4.5% and 6.5%). Results showed that the biofilm biomass was significantly reduced in L. monocytogenes mutant lacking sigB (P<0.05). According to the coefficient of variation analysis, all three of the culture conditions tested (i.e., temperature, pH and NaCl concentration) appeared to affect the strain variability of the biofilm formation of WaX12 and WaX12-ΔsigB, and the increase in the strain variability of biofilm formation caused by temperature is much greater than that caused by NaCl or pH. The ability of forming biofilm by WaX12-ΔsigB was more vulnerable to the effects of external culture conditions. There was a significant difference of biofilm biomass between WaX12 and WaX12-ΔsigB at 37℃, pH 6 and 2.5% NaCl, respectively, so the further research was observed under these culture conditions. Notably, results showed that the relative amounts of total polysaccharides and extracellular proteins were much lower in WaX12-ΔsigB biofilm (P<0.05). However, there was little influence on live cells. In conclusion, this study could provide a scientific basis for further investigation of the important role of sigB in L. monocytogenes biofilm formation.