Aquatic Microbiology - Science topic

If the microalgae's color changes from green to white or pale, it means the microalgae are dying or have died. You can confirm this by conducting a chlorophyll test under UV light to verify the growth and health of the microalgae.

@all The inability of Thalassiosira weissflogii microalgae to grow on agar plates with F2+Si medium, despite successful growth in a liquid starter culture indoors, could be due to several factors. Let's explore some possible reasons and potential solutions:

Remember that microalgae cultivation can be sensitive, and troubleshooting may involve several iterations to pinpoint the exact issue. Careful attention to the factors mentioned above and patience in experimenting with different conditions should help you successfully culture Thalassiosira weissflogii on agar plates with F2+Si medium.

@all Decreasing the salinity level in a larval rearing tank can be a delicate process, and it's important to minimize stress on the L. Vannamei post-larvae (PLs) during this transition. Here's a technical guide to help you decrease the salinity level while reducing stress and maintaining the PLs' well-being:

Remember, maintaining the health and well-being of the PLs is of utmost importance. Consult with experts in the field, gather data on the specific water conditions and PLs' responses, and make adjustments based on observed outcomes.

@all Apologies for the confusion in my previous response. You are correct that Thalassiosira weissflogii diatoms typically produce a brown color tint in the water rather than a green color. I apologize for the oversight in my previous explanation.

In the context of shrimp larval rearing tanks, the presence of a green color in the water is more commonly associated with the overgrowth of green algae, such as species from the genera Chlorella, Nannochloropsis, or Tetraselmis. These green algae can proliferate under favorable conditions and lead to the water turning green.

Excessive green algae growth can have various impacts on the larval rearing tank and the shrimp post-larvae (PL). While green algae themselves are not usually directly harmful to shrimp larvae, their overgrowth can indirectly affect the larvae and potentially lead to high mortality rates. Here are some possible reasons for the negative effects:

To prevent or manage excessive green algae growth and mitigate potential risks to the shrimp larvae, you can consider the following measures:

By maintaining optimal water conditions and preventing the overgrowth of green algae, you can help reduce stress on the shrimp post-larvae and minimize potential mortality rates.

Kristova Yubilius Indrataruna I have two suggestions for you: 1) Use ASNIII medium for marine CB: BG-11 was elaborated for freshwater CB; 2) Use very purified agarose (like Kim Sea) instead of either agar or gellan gum because very purified agarose does not support the proliferation of heterotrophs. Good luck. Igor Brown

How we can maintain the probiotic microbiome again quickly after water exchanges, in order to avoid pathogenic bacteria's bloom ? 1. Hatchery technician commonly use Bacillus sp. & lactobacillus probiotic powder directly apply it to the water or at the first we activated them by culture, 2. We should notice that water supply had been desinfected before use it, 3. We should maintain rasio C:N at raised more than 15, 4. We should control alkalinity as one of limiting factor for maintain probiotic as biofloc.

The role of volcanic activity as a significant factor contributing to ice melt still awaits a confirmation. For some further details please kindly consult the following site:

If the fungi are found on the Mars, it means that Carbon and Nitrogen are present there.

In my lab, we mostly store our microbial cultures either in soft agar covered with liquid sterile paraffin(molecular grade heavy/light) kept at 10°C to 12°C temperature or use glycerol stocks (70:30 or 80:20 ratio of LB broth & molecular grade glycerol) in 2 ml autoclaved cryovials & preserve it in -20°C. The advantage of storing culture in soft agar is culture can withstand if temperature much fluctuates also & It is durable for long time preservation if the surface of the agar properly covered with paraffin.

It shall be worth to attempt the formation of biofilms on both peg and well-surfaces to find out the actual preference of the organism to create such niche. Streptococcus mutans does form biofilm/ plaque formation on teeth and is nonmotile. Adherence may be modulated/ promoted by pre-exposure of the surface with sterile solution of some sugars [dextrose, sucrose etc.], amino acids [Lysine] and ECM [Collagen, fibronectin, albumin etc.].

There is no way to discriminate the two populations according to the red fluorescence signals. Chl autofluorescence and PI emission spectra overlap. However, there should be consistent morphological differences between micro-algae (generally bright large cells) and dead bacteria (generally smaller than microalgae), as they appear at the epifluorescence microscopy. If using flow cytometry, side and forward scatter signals still offer some opportunities for correct discrimination.

Hello Kevin. My team compared the biofilms on different brands of 96-wellplates (TC-treated, non-TC-treated), and found that some non-TC-treated plates (super cheap) had the lowest biofilm of the same bacteria. We then concluded that non-biofilm experiments can be used on certain non-TC-treated plates, while biofilm experiments should be used on TC-treated plates.

Agreed !

Dan - think that assumption is not valid.

Hi dear friend , I hope the following article will be useful to you

the principle of using Ca3PO4 in this medium in my opinion is to stimulate the production of organic acids by the strain, the indirect ones responsible for the solubilization of Ca3PO4 to make the P available in the medium which has repercussions on potassium solubilization of course.

According to my knowledge.

Testing of pathogenic bacterial effect to disinfection can be carried out by using E. coli.

There are bunch of product in market that sell packed E. coli.

You can also use EM4 or EM16 since its number of bacteria is already known.

Hope it will help.

Regrads.

Hello, it's an emerging topic both of interest & health concerns. For a time limited project, it would be nice if you confine your analysis within daily-life items, not only water but most commonly used processed food items packed in plastics. Good luck.

Your isolated bacteria may be belong to the non-capsulated serotype (KG+)(low virulent serotype) you may need increase the challenge dose or you try isolate the (KG-)serotype.

Regards

Nice pictures! In my view, you have enough information to be pretty confident that the isolate is Serratia - and probably S. marcescens. The glucose fermentation result is particularly useful to rule out some red/pink non-fermenting species. So unless the species ID is crucial, you could probably stop there. For definitive speciation, you would need to run some further biochemical tests or a commercial panel such as API 20E. For example, a test for ornithine decarboxylase would differentiate S. marcescens (+) from S. rubidaea (-), as the latter also produces the red prodigiosin pigment. Automated ID systems (if they are available to you) including MALDI-TOF MS should also give you a reliable species identification.

Based on the OIE-Listed Crustacean diseases 2017 report

1. Necrotizing Hepatopancreatitis (NHP) caused by NHP bacterium (NHPB)

2. ACUTE HEPATOPANCREATIC NECROSIS DISEASE (AHPND) caused by Vibrio parahaemolyticus

@Madhukar Baburao Deshmukh and @Leena Rao: bacterial urea hydrolysis is one such reaction which produces alkaline pH. Are there any other similar reactions which will produce alkaline pH?

Hi Sir,

In Forestry, I think it depends on the species  (Rhizobia/Plant). That could create invasive and competitive reactions disturbing ecosystems and biodiversity. 

Abdenour

The principle is straightforward; you need to be able to grow the Mycobacterium host as a lawn on the surface of an agar medium in a petri dish; and filter the enviromental samples through a 0.22 micron filter. 

Plate out the Mycobacterium and keep the plate open in the laminar flow for the surface to dry, then add then drop the  filtered aqueous samples onto the freshly plated agar surface (in a grid pattern) and incubate the plate. You can then purify the phage from an plaque that form.

I performed a different oxygen solubility test. 

Thank you Maria and Nicolas for answering and Nicolas, I must have misunderstood you, thank you for clarifying this point.

This can be anything, but probably NOT an organisme. You say it is 4-30 micron and that is extremely small, even for sponge spicules (and form and colour do not fit either, I think). But even when these things are larger, I still think it is some debris. What are the structures in the back ground?

Hi,

Verotoxin (vtx) or shiga-like toxin (stx) can be found in several E. coli serotypes including 0157:H7 and also Shigella dysenteriae. It was described in Germany an outbreak of this novel Escherichia coli O104:H4 which caused bloody diarrhea and hemolytic-uremic syndrome (HUS). Streptococcus pneumoniae, Campylobacter and viruses also can cause HUS.

Hope this could be helpfull.

They look like Paramecium feeding on red algae. They are very abundant  in stagnant basins and ponds of fresh water. Let me tell you the water in your swimming  pool needs a good dose of chlorine.

You may try with nile red dye which may be used in fluorescence

Certainly, they are used extensively and for several reasons, but not to detect and quantify bacteria, or to determine the species present. For that, samples are taken and sent to appropriate laboratories for analysis.

I'll recommend optical oxygen sensors for measuring the respiration rate. They are avaliable as microsensors, roubust sensor spots for non-invasive measurements or as 2D sensors for imaging and detecting hotspots. Its a pretty easy and straightforward detection and you can also monitor the respiration in real time. e.g. see links

It is important to know the actual irradiance level in the bioreactor (or any other cultivation system) you are using to impose the stress on the Haematococcus cells. First, the irradiance should be significantly higher than for growing green cells (e.g. 300-400 uE/m^2/s). It is desirable to check the irradiance at the surface and/or in the center of the cultivation vessel. Second, the suspension should not be too dense, otherwise the inner part of the suspension will be under-illuminated due to attenuation of light by superficial layers of the  suspension. Third, you need to be really sure that you do not carry over much nutrients with green cells to the cultivation system used to impose the stress. These conditions could be satisfied, to a certain degree, by dilution of the green culture with water. Good luck!

Thanks a lot on the other hand is the PCR test enough to confirm the results or we need other tests ?and what's there names ?

The aeromonas hydrophila colonies were isolated from the hemorrhages as well as the body fluids of the infected fish. Triplicate samples were aseptically blended with Tryptic Soy Broth (TSB) (Hi media,India) and incubated at 37⁰C overnight for enrichment. The culture was plated on Tryptic SoyAgar (TSA). The other colonies also identified byusing nutrient broth and the culture were grown innutrient agar. The selected isolates were identified by morphological, physiological and biochemical confirmations (Farmer and Hickman-Brenner,1992) as well as based on the characteristicsdescribed in Bergey’s Manual of SystematicBacteriology (Holt

et al., 1994). Further it was stored in nutrient agar slants at 4⁰ C for further experiments.

Try also diluted 1:1 media and NaCl additions

first of all analyze the stone surface by technique like spark erosion. This will tell you the minerals present on the stone surface and then expect those minerals to be present in the respective biofilm.

It is not a one step process. It needs expertise as well. diltution, then agar plating, then  observation of colonies under microscope, then again dilution and then again agar platiing. Read any book related to algal culture techniques

Ethanol precipitation worked well for my aquaculture sludge samples.

ıt is not possible to identify by the looking a bacteria but morfologicaly and movement style not similar to Flexibacter columnaris.

A lot of methylobacterias resist very well Bleach and Cl derivatives. They survive in purified freshwater. To rapid confirm, you can make a culture in petri dish with AMS + Metanol like carbon source. (table of page 3 http://personal.us.es/espuny/instrumentales/docs/tablas-teoria/Tablas_leccion_5.pdf ) They usually, it grows at 28 ° C

The TCBS medium, is an ideal medium to isolate vibrio species, this is because of the high concentrations the Thiosulfate-Citrate, bile and a high pH alcaline. The strains that can't degradate the sacarose are the green color, while the strains that can ferment the sacarose are the yelow color because produce acid as from the sugar. This is because of the color change to the pH indicator the Bromthymol Blue and Thymol Blue, which change to a yellow color in acid medium.

Have u tried storing it at 4OC?