Iron effects on colonization behavior, motility, and enzymatic activity of marine bacteria

2007 ◽  
Vol 53 (8) ◽  
pp. 968-974 ◽  
Author(s):  
Kam W. Tang ◽  
Hans-Peter Grossart
Keyword(s):  
Marine Bacteria ◽  
Laboratory Experiments ◽  
Large Fraction ◽  
Iron Limitation ◽  
Colonization Rate ◽  
Particle Interactions ◽  
Iron Availability ◽  
Free Living ◽  
Attached Bacteria ◽  
Colonization Behavior

Iron availability in the ocean has been shown to affect the growth and production of phytoplankton and free-living bacteria. A large fraction of marine bacteria are specialized in colonizing and living on particles and aggregates, but the effects of iron limitation on these bacteria are not fully known. We conducted laboratory experiments to study the effects of iron availability on particle colonization behavior, motility, and enzymatic activities of 4 strains of marine bacteria. Iron depletion reduced the bacterial particle colonization rate by 1.7%–43.1%, which could be attributed to reduced swimming speeds in 2 of the 4 strains. Protease activity was not affected by iron availability. However, attached bacteria did show higher protease activities than their free counterparts. Our results suggest that iron limitation in the ocean could in some cases reduce bacteria–particle interactions by reducing bacterial motility and colonization rate.

The dynamics of attached and free-living bacterial population in tropical coastal waters

2015 ◽  
Vol 66 (8) ◽  
pp. 701 ◽  
Author(s):  
Siew Wen Lee ◽  
Choon Weng Lee ◽  
Chui Wei Bong ◽  
Kumaran Narayanan ◽  
Edmund Ui-Hang Sim
Keyword(s):  
Coastal Waters ◽  
Bacterial Population ◽  
Bacterial Abundance ◽  
Large Fraction ◽  
Free Living ◽  
Water Port ◽  
Eutrophic Water ◽  
Attached Bacteria ◽  
Student’S T ◽  
Student’S T Test

We investigated the dynamics of attached and free-living bacterial abundance over a period of 18 months in tropical coastal waters of Malaysia. We measured the abundance at both oligotrophic coastal water (Port Dickson) and eutrophic estuary (Klang), and hypothesised that attached bacteria are predominant in eutrophic waters. We found that bacterial abundance was higher at Klang than Port Dickson (Student’s t-test: t=4.87, d.f.=19, P<0.001). Attached bacteria also formed a large fraction of the total bacteria at Klang (75% ±13s.d.) relative to Port Dickson (56% ±22), and showed preference for chlorophyll-a-based particles rather than total suspended solids. The bacterial community structure was clearly different between the two stations but was similar between the attached and free-living bacterial population. Our results showed the importance of attached bacteria in eutrophic water where they could play a major role in carbon and nutrient cycling.

scholarly journals Effects of iron on the elemental stoichiometry during EIFEX and in the diatoms <i>Fragilariopsis kerguelensis</i> and <i>Chaetoceros dichaeta</i>

2007 ◽  
Vol 4 (1) ◽  
pp. 249-275 ◽  
Author(s):  
L. J. Hoffmann ◽  
I. Peeken ◽  
K. Lochte
Keyword(s):  
Laboratory Experiments ◽  
Iron Limitation ◽  
Iron Availability ◽  
Diatom Species ◽  
Fertilization Experiment ◽  
High Iron ◽  
Iron Fertilization ◽  
Elemental Stoichiometry ◽  
Fertilization Experiments

Abstract. The interaction between iron availability and the phytoplankton elemental composition was investigated during the in situ iron fertilization experiment EIFEX and in laboratory experiments with the Southern Ocean diatom species Fragilariopsis kerguelensis and Chaetoceros dichaeta. Contrary to other in situ iron fertilization experiments we observed an increase in the bPSi : POC, bPSi : PON, and bPSi : POP ratios within the iron fertilized patch during EIFEX. This is possibly caused by a relatively stronger increase in diatom abundance compared to other phytoplankton groups and does not necessarily represent the amount of silicification of single diatom cells. In laboratory experiments with F. kerguelensis and C. dichaeta no changes in the POC : PON, PON : POP, and POC : POP ratios were found with changing iron availability in both species. BPSi : POC, bPSi : PON, and bPSi : POP ratios were significantly lower in the high iron treatments compared to the controls. In F. kerguelensis this is caused by a decrease in cellular bPSi concentrations and therefore possibly less silicification. In C. dichaeta no change in cellular bPSi concentration was found. Here lower bPSi : POC, bPSi : PON, and bPSi : POP ratios were caused by an increase in cellular C, N, and P under high iron conditions. We therefore assume that iron limitation does not generally increase silicification of diatoms and that changes in the bPSi : POC, bPSi : PON, and bPSi : POP ratios under iron fertilization in the field are caused by a variety of different mechanisms. These results imply that the effect of iron on nutrient uptake is more complex than hitherto assumed.

Capture of conspecific planktonic larvae by the suspension-feeding gastropod Crepipatella peruviana: association between adult and larval size

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
G A Rivera-Figueroa ◽  
J A Büchner-Miranda ◽  
L P Salas-Yanquin ◽  
J A Montory ◽  
V M Cubillos ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Larval Mortality ◽  
Feeding Preference ◽  
The Other ◽  
Suspension Feeding ◽  
Adult Size ◽  
Free Living ◽  
Larval Size ◽  
Suspension Feeders ◽  
Planktonic Larvae

ABSTRACT Free-living, planktonic larvae can be vulnerable to capture and ingestion by adult suspension-feeders. This is particularly the case for larvae that settle gregariously in benthic environments where suspension-feeders occur at high densities. Larvae of gregarious suspension-feeding species are at particularly high risk, as adults of their own species often serve as cues for metamorphosis. We conducted laboratory experiments to assess the extent to which adults of the suspension-feeding caenogastropod Crepipatella peruviana would capture and ingest their own larvae. Experiments were conducted with adults of different sizes, with larvae of different ages and sizes, and in the presence or absence of phytoplankton. Adults captured larvae in all experiments. The presence of microalgae in the water did not influence the extent of larval capture. On average, 39% of larvae were captured during the 3-h feeding periods, regardless of adult size. However, up to 34% of the larvae that were captured on the gill were later discarded as pseudofaeces; the other 64% were ingested. The extent of capture by adults was not related to adult size, or to larval size and, thus, to larval age. Our results suggest that the filtration of congeneric larvae by adult C. peruviana is a result of accidental capture rather than a deliberate feeding preference. Such ingestion could, however, still be an important source of larval mortality, especially when the advanced larvae of this species are searching for a suitable substrate for metamorphosis.

scholarly journals Diversity of Free-Living and Attached Bacteria in Offshore Western Mediterranean Waters as Depicted by Analysis of Genes Encoding 16S rRNA

1999 ◽  
Vol 65 (2) ◽  
pp. 514-522 ◽  
Author(s):  
Silvia G. Acinas ◽  
Josefa Antón ◽  
Francisco Rodríguez-Valera
Keyword(s):  
16S Rdna ◽  
Restriction Analysis ◽  
Western Mediterranean ◽  
Bacterial Cells ◽  
Free Living ◽  
Attached Bacteria ◽  
Genes Encoding ◽  
Community Fingerprinting ◽  
Close Relatives ◽  
Alteromonas Macleodii

ABSTRACT In a previous study (S. G. Acinas, F. Rodrı́guez-Valera, and C. Pedrós-Alió, FEMS Microbiol. Ecol. 24:27–40, 1997), community fingerprinting by 16S rDNA restriction analysis applied to Mediterranean offshore waters showed that the free-living pelagic bacterial community was very different from the bacterial cells aggregated or attached to particles of more than about 8 μm. Here we have studied both assemblages at three depths (5, 50, and 400 m) by cloning and sequencing the 16S rDNA obtained from the same samples, and we have also studied the samples by scanning electron microscopy to detect morphology patterns. As expected, the sequences retrieved from the assemblages were very different. The subsample of attached bacteria contained very little diversity, with close relatives of a well-known species of marine bacteria, Alteromonas macleodii, representing the vast majority of the clones at every depth. On the other hand, the free-living assemblage was highly diverse and varied with depth. At 400 m, close relatives of cultivated γProteobacteria predominated, but as shown by other authors, near the surface most clones were related to phylotypes described only by sequence, in which the α Proteobacteria of the SAR11 cluster predominated. The new technique of rDNA internal spacer analysis has been utilized, confirming these results. Clones representative of the A. macleodii cluster have been completely sequenced, producing a picture that fits well with the idea that they could represent a genus with at least two species and with a characteristic depth distribution.

Diversity in surface colonization behavior in marine bacteria

1996 ◽  
Vol 17 (3-4) ◽  
pp. 228-234 ◽  
Author(s):  
H M Dalton ◽  
A E Goodman ◽  
K C Marshall
Keyword(s):  
Marine Bacteria ◽  
Surface Colonization ◽  
Colonization Behavior

scholarly journals Regulation of freA, acoA, lysF, and cycA Expression by Iron Availability in Aspergillus nidulans

2002 ◽  
Vol 68 (11) ◽  
pp. 5769-5772 ◽  
Author(s):  
Harald Oberegger ◽  
Michelle Schoeser ◽  
Ivo Zadra ◽  
Markus Schrettl ◽  
Walther Parson ◽  
...  
Keyword(s):  
Aspergillus Nidulans ◽  
Iron Homeostasis ◽  
Regulatory Mechanism ◽  
Growth Conditions ◽  
Iron Limitation ◽  
Transcriptional Level ◽  
Iron Availability ◽  
Gata Factor ◽  
Genes Encoding ◽  
Encoding Gene

ABSTRACT In the filamentous fungus Aspergillus nidulans, iron homeostasis is regulated at the transcriptional level by the negative-acting GATA factor SREA. In this study the expression of a putative heme-containing metalloreductase-encoding gene, freA, was found to be upregulated by iron limitation independently of SREA, demonstrating the existence of an iron-regulatory mechanism which does not involve SREA. In contrast to freA, various other genes encoding proteins in need of iron-containing cofactors—acoA, lysF, and cycA—were downregulated in response to iron depletion. Remarkably, SREA deficiency led to increased expression of acoA, lysF, and cycA under iron-replete growth conditions.

Nematophagous fungi in pasture: colonisation of sheep faeces and their potential for control of free-living stages of gastro-intestinal nematode parasites of sheep

2002 ◽  
Vol 42 (1) ◽  
pp. 7 ◽  
Author(s):  
F. S. Hay ◽  
J. H. Niezen ◽  
D. Leathwick ◽  
R. A. Skipp
Keyword(s):  
Laboratory Experiments ◽  
Nematophagous Fungi ◽  
Soil Nematodes ◽  
Arthrobotrys Oligospora ◽  
Free Living ◽  
Intestinal Nematode ◽  
Nematode Parasites ◽  
Fungal Propagules ◽  
Third Stage ◽  
Filter Type

Sheep faeces placed on a pasture in New Zealand in February and April were retrieved at intervals up to 28 days and examined for fungi that parasitise nematodes (nematophagous fungi). Monacrosporium haptotylum, Harposporium bysmatosporum, H. helicoides and a Nematoctonus sp. were present, respectively, in 37, 22, 13 and 8% of 283 samples retrieved in February and from 29, 14, 11 and 15% of 200 samples retrieved in April. Fungi entered faeces rapidly, being present in 35 and 54% of samples retrieved after 3 days in February and April, respectively. The ability of migrating soil nematodes to carry fungal propagules from soil into faeces was assessed in 2 laboratory experiments. Sheep faeces separated from soil by filters that allowed passage of both nematodes and fungi was colonised by H. helicoides more frequently than faeces on filters that excluded nematodes, indicating nematodes were vectors. However, Arthrobotrys oligospora, M. haptotylum and A. brochopaga occurred in faeces independently of filter type, indicating that these species grew into faeces. Two laboratory experiments examined the ability of nematophagous fungi, when inoculated into sheep faeces containing eggs of the gastro-intestinal nematode parasite Trichostrongylus colubriformis to reduce the number that developed to third-stage larvae. Monacrosporium gephyropagum, A. cladodes, A. conoides and A. oligospora reduced the number of third-stage larvae that emerged by 54–91% (P<0.05) in comparison to a control; however, M. haptotylum and H. bysmatosporum were ineffective. In a second experiment, several species of nematophagous fungi reduced the number of third-stage larvae that emerged by 41–96% (P<0.05) in comparison to a control, while others had no effect.

Biogeography of the free-living and particle-attached bacteria in Tibetan lakes

2019 ◽  
Vol 95 (7) ◽  
Author(s):  
Keshao Liu ◽  
Juzhi Hou ◽  
Yongqin Liu ◽  
Anyi Hu ◽  
Mingda Wang ◽  
...  
Keyword(s):  
Free Living ◽  
Attached Bacteria
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