Bioleaching of heavy metals from contaminated alkaline sediment by auto- and heterotrophic bacteria in stirred tank reactor

Bioleaching Xiangjiang River alkaline sediment contaminated by multiple heavy metals was investigated. Multiple metals in alkaline sediment possess significant toxicity to aquatic organisms or humans and will greatly inhibit bioleaching. The bioleaching method using autotrophic bacteria mixed with heterotrophic bacteria can solve this problem successfully. The experiment results showed that bioleaching efficiencies of Zn, Mn, Cu, and Cd were 95.2 %, 94.2 %, 90.1 %, and 84.4 %, respectively. Moreover, the changes of heavy metal concentrations in different fractions in contaminated sediment before and after bioleaching were analyzed by selective sequential extraction, and it was discovered that the main fractions of Zn, Mn, Cu and Cd after bioleaching are Fe-Mn oxide, organic associated form and a residual form. Its biotoxicity decreased greatly. The bioleaching heavy metals from sediment using autotrophic bacteria combined with heterotrophic bacteria can effectively improve the bioleaching efficiency and reduce toxicity.

Abundance of general aerobic heterotrophic bacteria in the Bering Sea and Chukchi Sea and their adaptation to temperature

The abundance of general aerobic heterotrophic bacteria(GAB) from the water and sediment in the Bering Sea and the Chukchi Sea was determined by using petri dish cultivation and counting method. The abundance of GAB among the different sea areas, sampling sites, layers of sediments surveyed and adaptability to differential temperatures was studied. The result obtained showed that: the occurrence percentage of GAB in the surface water was higher than that in sediment, but the abundance was only 0.17% of sediment. The occurrence percentage of GAB in surficial layer of sediment was higher than that in the other layers. The occurrence percentage of GAB in surficial layer of sediment was higher than that in the other layers. The occurrence percentage, abundance and its variation of GAB in the Bering Sea were higher than that in the Chukchi Sea respectively. The average value of the abundance in the all sediment surveyed was 3166.3×10 2 CFU·g -1(wet.). The abundance of GAB in sediment showed a trend: roughly higher in the lower latitudinal area than higher latitude. The results from temperature test mean that: the majority of bacteria tested were cold-adapted ones, minority might be mesophilic bacteria. The results indicated that, Arctic ocean bacteria had a stronger adaptability to environmental temperature.

Heterotrophic bacteria of the Dapeng Bay in the South China Sea: community structure,abundance,and the relationships of culturablity with environmental factors

The community composition,abundance and culturablity of heterotrophic bacterioplankton in the Dapeng Bay of the South China Sea were investigated by morphological method,bacterial cultivation and biochemical methods over an annual cycle.Aeromonas and Pseudomonas were the predominant genera among the Gram-negative bacteria.The bacterioplankton abundance fluctuated from 2.07×10 8 to 2.44×10 9 cells/dm 3 ,and culturable bacteria abundance ranged between 0.1×10 6 and 16.07×10 6 CFU/dm 3 .The Culturablity of heterotrophic bacteria ranged between 0.01% and 1.31%.The relationship between bacterial culturablity and the environmental factors was also studied in different sites of the Dapeng Bay.Throughout the bay,a significantly positive relationship was evidenced between bacterial culturability and temperature,meanswhile bacterial culturability was significantly inversely related with salinity.The positive relationship was shown at the central bay while a negative relationship was observed at the bay mouth and there was no significant correlation at top bay between bacterial culturablity and chlorophyll a of sea water.A positive relationship was found between culturability and DIN all the bay,but DIP showed a significantly negative relationship with bacterial culturability only at the mouth of the bay.

Response of Heterotrophic Bacteria Abundance and Community Structure to Asian Dust Addition in the Oligotrophic Northwest Pacific Ocean

The dust storms from the continent usually affect the abundance and diversity of planktons by supplying trace elements. As such, the response of heterotrophic planktonic bacteria to dusts, nutrients(i.e., nitrogen and phosphorus) or ferrous dosages was investigated in the Kuroshio Extension region of the Northwest Pacific Ocean(NWPO) through on-board incubation experiments during an oceanographic survey in spring 2014. The flow cytometry and 16S rRNA high-throughput sequencing methods were applied to explore the abundance and community structure of bacteria, and the percentage of high nucleic acid bacteria(HNA%). The results showed that the heterotrophic bacteria abundance was low(average 2.55×10^5 cells mL^-1) and subjected to both nitrogen(N) and ferrous(Fe) limitation. Sand-dust deposition observably promoted the activity of heterotrophic planktonic bacteria. The maximum abundance of heterotrophic bacteria was 6.98×10^5 cells mL^-1 in the dust-dosage group, which was 44% higher than the control(P < 0.05). The HNA% in the dust-dosage group was 1.37 times higher than the control(P < 0.05). The activation mechanism was mainly related to the dissolution of N and Fe in the dusts. The relative abundance of genus Winogradskyella was significantly increased by dust deposition while the relative abundance of the genera Tenacibaculum and Hyphomonas was decreased. These variations of bacterial community structure were ascribed to the dissolution of nutrients N and P. Comparing the results of different experimental groups, this study concluded that dust storm improved the abundance of heterotrophic bacteria by dissolution of N and Fe.

Heterotrophic Bacterial Floras in Industrial Area and Unpolluted Marine Environments around Qingdao

From Oct. 1999 to Oct. 2000, the heterotrophic bacterial floras in the industrial marine environment around the Qingdao Power Plant (QPP) and in the unpolluted marine environments were investigated. The results showed that the numbers of the heterotrophic bacteria around QPP were much higher than those in unpolluted environments, and the average numbers in QPP Seawater, QPP Sediment, Unpolluted Seawater and Unpolluted Sediment were 5.4×104cfu(mL) -1, 5.0×105cfug -1, 3.0×102cfu(mL) -1 and 1.3×105cfug -1 respectively. Totally, 118 strains were isolated from QPP and 99 of them were Gram-negative. One hundred and twenty one strains were isolated from the unpolluted environments and 104 of them were Gram-negative. All the Gram-negative bacteria belonged to 13 genera. The distribution of the bacteria was varied in different marine environments. The results showed that the unpolluted marine environments contained much more Vibrio than seawater and sediment around QPP.

Heterotrophic Bacterial Flora in Aquaculture Area around Xuejiadao

From Oct., 1999 to Oct., 2000, the heterotrophic bacterial flora in the aquaculture area around Xuejiadao was investigated. The result shows that the populations of the heterotrophic bacteria are heavier in summer and autumn than those in winter and spring. The average populations in seawater, sediment, the surface of seaweed and the surface of fish are 1.4×10 4 cfu mL -1, 5.4×10 6 cfu g -1, 1.5×10 6 cfu g -1 and 1.8×10 3 cfu cm -2, respectively. A total of 301 strains were isolated, among them 259 were Gram-negative. All the Gram-negative bacteria belong to 13 genera and some genera of Enterobacteriaceae. The communities of bacteria are slightly different among the samples. In the body surface of fish, Genus vibrio is dominant. In the remaining samples, dominant genus is Aeromonas.

Response of Marine Microalgae,Heterotrophic Bacteria and Their Relationship to Enhanced UV-B Radiation

Ozone depletion in the stratosphere has enhanced solar UV-B radiation reaching the Earth surface and has brought about significant effects to marine ecosystems. The effects of enhanced UV-B radiation on marine microalgae, heterotrophic bacteria and the interaction between them are discussed. The effects on marine microalgae have been proved to occur at molecular, cellular and population levels. Enhanced UV-B radiation increases microalgal flavonoid content but decreases their chlorophyll content and pho- tosynthesis rate; this radiation induces genetic change and results in DNA damage and change of protein content. There have been fewer studies on the effects of UV-B radiation on marine heterotrophic bacteria. Establishment of a microalgal ecological dynamic model at population and commuity levels under UV-B radiation has gradually become a hotspot. The effects of enhanced UV-B radiation on microalgae commtmities, heterotrophic bacterial populations and interaction between them will become a focus in the near future. This paper will make an overview on the studies concerning the effects of enhanced UV-B radiation on marine microalgae and heterotrophic bacteria and the interaction between them.

Geographical distribution of general aerobic heterotrophic bacteria in surficial sediments from the Chukchi Sea and Canadian Basin

This paper determined the abundance of General Aerobic heterotrophic Bacteria （GAB） in surficial sediments from the Chukchi Sea and the Canadian basin by using MPN and discussed their geographical distribution. The result shows that the determination percentages of the GAB were high, even till 100 percentage. The abundance range and averages of GAB for 4℃and 25℃ were from 4.00 × 10^2 to 2.40× 10^6 , 1.71×10^6 ind.·g^-1 （wet sample ） and from 2.40 ×10^5 to 2.40×10^7 , 1.10×10^7 ind. ·g^-1 （wet sample ） respectively. Not only the abundance range but also the averages of GAB in 25℃ were higher than that in 4℃. The abundance of GAB in sediments show a tendency that it is roughly greater in the lower latitudinal area than in the higher latitudinal area. The abundance of GAB increased from east to west as for the longitudinal distribution. With the water depth increasing, the abundance of GAB at 4℃ decreased, but GBA at 25℃ is not changed obviously with water depth. It seems that warmer circumstantial temperature is more suitable for some GAB.

A study on relation between heterotrophic bacteria and shrimp disease

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Autotrophic potential in mesophilic heterotrophic bacterial isolates from Sino-Pacific marine sediments

Microbial carbon fixation is a paramount process in the ocean especially below the photic zone both in water and sedimentary ecosystems. Autotrophic microbes that fix carbon dioxide are renowned. However, the question whether heterotrophs can also fix carbon is intriguing. Ten heterotrophically grown, identified bacterial isolates from the Sino-Pacific marine sediments were tested for autotrophic uptake potential with and without addition of electron donors. Nine of the ten isolates showed carbon uptake capacity without addition of any substrate at very low rates in the order of 10^（-8） to 10^（-4） fmol/（cell·h）. The addition of manganese and ammonium at 1 mmol/L final concentration enhanced the uptake potential. Addition of 1 mmol/L final concentrations of reduced iron（10^（-6） to10^（-5） fmol/（cell·h） and sulfide（10^（-5） fmol/（cell·h） decreased the uptake potential significantly at p〈0.1. Bacterial tolerance to formaldehyde suggested propensities of anaplerotic chemical reactions that form metabolic intermediates of C-1 metabolism pathways. The isolates displayed high metabolic flexibility. With the changes in electron donors, the isolates metabolically toggled between relatively anoxic reductive iron/sulfur cycles and the oxidative cycles of manganese/ammonium and vice-versa. This property makes these microbes successful survivors in the highly dynamic Sino-Pacific sediments.

Improving dryland maize productivity and water efficiency with heterotrophic ammonia-oxidizing bacteria via nitrification and cytokinin activity

A two-year field experiment conducted under dryland conditions in semi-humid and drought-prone regions of China aimed to assess the effect of ammonia-oxidizing bacterial on maize water use efficiency and yield.A heterotrophic ammonia-oxidizing bacteria(HAOB)strain S2_8_1 was used.Six treatments were applied:(1)no irrigation+HAOB strain(DI),(2)no irrigation+blank culture medium(DM),(3)no irrigation control(DCK),(4)irrigation+HAOB(WI),(5)irrigation+blank culture medium(WM),and(6)irrigation control(WCK).Results revealed that HAOB treatment increased maize growth,yield,and water use efficiency over controls,regardless of whether the year was wet or dry.This improvement was attributed to the accelerated nitrification in the rhizosphere soil due to HAOB inoculation,which subsequently led to increased levels of leaf cytokinins.Overall,these findings suggest that HAOB inoculation holds promise as a strategy to boost water use efficiency and maize productivity in dryland agriculture.

Distribution Pattern of Photosynthetic Picoplankton and Heterotrophic Bacteria in the Northern South China Sea

The environmental regulation of plcoplankton distribution in the northern South China Sea was examined In winter and summer of 2004. The average abundance of Synechococcus, Prochlorococcus, and heterotrophlc bacteria was lower In winter （30, 21, and 780×10^3 cells/cm^3, respectively） than In summer （53, 85, and 1 090×10^3 cells/cm^3, respectively）, but the seasonal pattern was opposite for plcoeukaryotlc phytoplankton （4 500 and 3 200 cells/cm^3 In winter and summer, respectively）. Synechococcus, picoeukaryotes, and bacteria were most abundant in the nutrient-rich coastal zone and continental shelf, but Prochlorococcus was most abundant In the continental slope and open ocean. The vertical distribution of each photosynthetic group and heterotrophlc bacteria changed between the two seasons. Synechococcus populations with apparently different phycoerythrobilin content occurred at many stations In the summer. In addition, two different populations of Prochlorococcus were found： （i） small, weakly fluorescing cells in the surface layer; and （ii） larger, strongly fluorescent cells In the deep layer. The distribution pattern of photosynthetic plcoplankton and heterotrophlc bacteria depends on environmental effects and their ecophyslologlcal differences. The distribution of Synechococcus appeared to be related to nutrient availability, whereas the distribution of Prochlorococcus appeared to be limited by temperature. Synechococcus was the only plcophytoplankton with a consistent strong relationship with bacteria.

Sulfur metabolism by marine heterotrophic bacteria involved in sulfur cycling in the ocean

Sulfur cycling in the biosphere is tightly interwoven with the cycling of carbon and nitrogen,through various biological and geochemical processes.Marine microorganisms,due to their high abundance,diverse metabolic activities,and tremendous adaptation potential,play an essential role in the functioning of global biogeochemical cycles and linking sulfur transformation to the cycling of carbon and nitrogen.Currently many coastal regions are severely stressed by hypoxic or anoxic conditions,leading to the accumulation of toxic sulfide.A number of recent studies have demonstrated that dissimilatory sulfur oxidation by heterotrophic bacteria can protect marine ecosystems from sulfide toxicity.Sulfur-oxidizing bacteria have evolved diverse phylogenetic and metabolic characteristics to fill an array of ecological niches in various marine habitats.Here,we review the recent findings on the microbial communities that are involved in the oxidation of inorganic sulfur compounds and address how the two elements of sulfur and carbon are interlinked and influence the ecology and biogeochemistry in the ocean.Delineating the metabolic enzymes and pathways of sulfur-oxidizing bacteria not only provides an insight into the microbial sulfur metabolism,but also helps us understand the effects of changing environmental conditions on marine sulfur cycling and reinforces the close connection between sulfur and carbon cycling in the ocean.

Diversity of culturable heterotrophic bacteria from the Mariana Trench and their ability to degrade macromolecules

The Mariana Trench is the deepest location on earth and harbors unique microbial communities as evidenced by 16S rRNA gene amplicon and metagenomic sequencing.Obtaining culturable microorganisms from the Mariana Trench will contribute to a further understanding of hadal biogeochemical processes and act as a unique microbial reservoir with potential applications.Here,825 bacterial strains,identified by 16S rRNA gene sequencing,were isolated from 12 water depths(0-10,400 m)of the Mariana Trench with 2216E and R2A media at 4℃ or 28℃ on four cruises during 2015-2017.These bacteria belong to four phyla,nine classes,27 orders,45 families and 108 genera.Alphaproteobacteria,Gammaproteobacteria,Actinobacteria_c,Bacilli and Flavobacteriia were the most abundant classes,accounting for 37.9%,33.0%,11.8%,8.6%and 8.0%of the total bacterial isolates,respectively.2216E and R2A media were found to have a better selectivity to Bacilli and Flavobacteriia,respectively.Fifty strains were potential novel bacterial species with a 16S rRNA gene similarity<98.65%,and a higher percentage of novel strains were obtained from R2A than 2216E medium.Additionally,301(150 species)out of 354 strains(178 species)selected from each depth could degrade at least one of the ten kinds of macromolecules tested.These results indicate that there is a high diversity of culturable bacteria in the Mariana Trench and they can produce a variety of extracellular enzymes.Our study provides a valuable resource of microorganisms for investigating their biogeochemical roles in the Mariana Trench and for industrial applications.

Nitrate assimilation by marine heterotrophic bacteria

Nitrate assimilation is a process where bacteria utilize nitrate as a nitrogen source and synthesize it into organic nitrogen. We found that nitrate-assimilating bacteria(NAB) are widely distributed in various marine environments, from surface to the deep ocean and sediment, which indicates that NAB are significant to the oceanic nitrogen cycle. Comparative genomic analysis revealed nitrate-assimilating genes(nas A) in these marine heterotrophic NAB showed different gene arrangements and diverse regulation systems. Summary on recent findings will contribute to understanding the process of nitrate assimilation in NAB and their ecological significance in the nitrogen cycle. A systematic analysis of a number of studies on bacterial nitrate assimilation in marine ecological systems was conducted to clarify directions for future research.

Impact of 17β-Estradiol on Natural Water’s Heterotrophic Nitrifying Bacteria

In this research, bottom water samples were collected from nature water. After cultivating and selecting, bacteria which could use (NH4)2SO4 as the only nitrogen source had been selected. The bacteria were cultivated in BM cultures with 0, 0.1, 1, 10, 100 ng/L 17β-estradiol (E2), and the initial concentration of E2 is the only difference between cultures of each group. BM culture is a kind of bacteria culture with 100 mg/L of NH4-N as only nitrogen source. Every group’s N- NH4+, N- NO3-concentration and OD600 were measured. The result shows that compared with the control group, in which no E2 was added, the growth of heterotrophic nitrifying bacteria had been promoted when the concentration of E2 was in range of 1 - 100 ng/L. In addition, heterotrophic nitrifying bacteria’s growing speed has a positive correlation between the E2’s concentration. However, low concentration of E2 (like 0.1 ng/L), could inhibit the growth of heterotrophic nitrifying bacteria. Considering the impact of E2 on heterotrophic nitrifying bacteria, it is necessary to intensify the detection of E2 in the future.

Study on the Quantity Dynamic Changes of Heterobacteria and Vibrios in Larvae Industrialized Culture System

[ Objective ] The dynamic change of heterobacteria and vibrios in larvae industrialized culture system was studied to provide scientific reference for healthy cultivation of shrimp. [ Method ] The heterobacteria, vibrios and pathogenic vibrio parahaemolyticus were monitored in larvae industrialized culture system. [ Result] The heterobacteria, vibrios and pathogenic vibrio parahaemolyticus were the most in fertilized eggs of shrimp but the least in nauplius, then their number would increase with growth. During whole rearing period, both boterobacteria in larvae, vibrios in water would increase by one order of magnitude, while both vibrios in larvae and heterobacteria in water would increase by two orders of magnitude. There were many heterobacteria and vibrios but few vibrio parahaemolyticus in living bait. The correlation coefficients between larvae and heterobacteria and vibrios in water were 0. 704 and 0. 840 in culture system respectively, while the correlation among heterobacteria, vibrios in living bait and larvae, water were weak or negative. [ Conclusion ] There was a dynamic relation between water and larvae in rearing period, and restrictly control of culture condition would restrain the occurrence of disease caused by vibrio parahaemolyticus, besides that bacteria number in bait was not obviously correlated with bacteria nubmer in culture system.

Community diversity of bacteria in digestive tract of mud snail (Bullacta exarata Philippi) and its rearing shoal

The bacterial flora in the digestive tract of B. exarata Philippi and its rearing shoal were investigated, respectively. A total of 107 strains of heterotrophic bacteria, isolated from crop, stomach and intestine, mainly belong to genera Photobacterium, Bacillus, Pseudomonas and Vibrio. Varieties of bacteria in crop were significantly more than that in stomach and in intestine. A total of 173 strains of bacteria were isolated from the rearing shoal, belonging to 13 genera. The 5 predominant genera are Photobacterium, Bacillus, Pseudomonas, Vibrio and some genera of Enterobacteriaceae. The number of heterotrophic bacteria and Vibrio in rearing shoal changed in line with the alteration of the temperature, and were significantly affected by the use of pesticide.

HETEROTROPHIC BACTERIOPLANKTON PRODUCTION IN THE EAST CHINA SEA

Heterotrophic bacterial production (BP) in the East China Sea was measured using tritiated thymidine incorporation (TTI) method in winter 1997 and in summer 1998. The results showed BP in summer (1998, 3.50-15.70 μgC/(L·h) was higher than that in winter(1997, 0.46-2.62 μgC/(L·h). The high values of BP occurred around the Changjiang River estuary and around Station 410. The results at two anchor stations showed that vertical variation of BP was bottom>middle>surface in winter and middle>bottom>surface in summer. Compared with primary production (BP:PP), the average ratio of BP:PP was 0.17(0.04-0.30) in winter and 0.32(0.21-0.43) in summer. There were high ratios around the Changjiang River estuary in winter and around Station 111 in summer.

Dynamics of picoplankton in the Nansha Islands area of the South China Sea

Dynamics of major picoplankton groups, Synechococcus (Syn), Prochlorococcus (Pro), picoeukaryotes (Euk) and heterotrophic bacteria (Bact) was investigated by flow cytometry for the first time in the Nansha Islands area in the South China Sea. Averaged over the whole investigation area, depth-weighted integrated cell abundance (DWA) of Syn, Pro, Euk and Bact was 1.6 (0.4-5.7)×103, 5.4 (0.1-7.3)×104, 0.7 (0.2-2.2)×103, and 2.3 (1.4-3.2)×105 cells/mL respectively. Picoautotrophic cell abundance was low in the northwest part of the Nansha Islands where surface water temperature was low and the upper mixed layer was shallow. Concurrently, a surface maximum vertical distribution pattern was observed in this area. While in the southeast and east zones where temperatures were relatively higher and nitraclines were deeper, picoplankton is abundant and a subsurface maximum around 50-75 m is observed. Coupling of horizontal and vertical distribution patterns of picoplankton abundance and hydrological status was found, suggesting a strong influence of currents and water column structure on picoplankton distribution in the investigation area. Contrary to that in the shelf water in the East China Sea, the relationship between Pro and Bact in the Nansha Islands area in the South China Sea was not significantly negative but weakly positive. Moreover, a similar distribution pattern of Syn and Pro was observed. Possible reasons for these differences in the two marine regimes were discussed.