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Author Topic: How would I identify starch-utilising bacteria?  (Read 2755 times)

Offline iperez_genius

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How would I identify starch-utilising bacteria?
« on: 27/03/2008 11:30:54 »
I am wondering if someone can help me.

I have an assignment in regards starch utilising bacteria

I have found many different experiments using patatoes.

I have no idea how to find what different bacteria would exist on the patatoes after a week.

and by the different bacteria i mean the names or types of bacteria.

Can anyone help

thanks in advance

Mod edit - formatted the subject as a question.  Please try to do this to help keep the forum tidy and easy to navigate - thanks!
« Last Edit: 31/07/2008 11:37:05 by BenV »


Offline Karen W.

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How would I identify starch-utilising bacteria?
« Reply #1 on: 26/08/2008 16:12:07 »
Welcome to the forum!
This link lists over 350 bacteria's from potato's.  You do need to click on all the pages at the bottom blue links:


Expt 3. Autoclaved Potato slices. You won't have lots of success with gelatin media because in a warm room, they melt. Yet, solid media are so useful, the search went on. Potato slices are a good medium for some bacteria and many fungi. Great strides in bacteriology began when solid media were developed. Potato slices are prepared in a professional lab by putting slices in glass petri dishes and autoclaving. You can make your own dishes in many ways: You could use glass jars with loose lids. Try putting 1/4 inch thick slices of potato in a jar and then place it in a pressure cooker. Autoclave (cook) it for 15 minutes at 15 pounds pressure. Fiveteen pounds is the normal pressure for home pressure cookers. Of course you put jar cover on loosely before you begin autoclaving. Beside the potato jar, you could autoclave a bottle containing some tooth picks. Later you can use he sterile tooth picks to tranfer bacteria from colonies. Let it cool in the cooker, then remove. Open the lid of the jar in any room and let unseen dust particles fall into the jar for a few minutes. Replace jar lid loosely, and leave jar at room temperature a day or longer. You should see colonies of bacteria growing. Yellow colonies are frequent and orange may be found. The yellow colonies are often Micrococcus bacteria or yeasts. The oranage may be yeasts. I believe most od hese colored colonies are safe and ones for the beginner to study.

Mystery bacteria linked to US potato disease
Home News Farming
Thu, 24 Jul 2008
News: Farming

A plant disease scare in tomatoes, which triggered biosecurity bans on New Zealand potatoes, tomatoes and capsicums, has now been linked to a disease in American potato crops.

And the potato disease, known as "zebra chip", has now been discovered in an Auckland spud crop, NZPA has been told.

The disease-causing Candidatus liberibacter bacteria species disrupted New Zealand exports last month when agriculture authorities revealed its discovery in three Auckland commercial hothouses in January.

The announcement by NZ scientists that it was a previously unrecorded form of C. liberibacter spooked some key export customers, as it is related to huanglongbing disease - also known as citrus greening. The warnings also unfortunately coincided with overseas headlines about an unrelated bacteria - salmonella - on tomatoes in America making people sick.

Australia blocked imports of tomatoes, capsicum and potatoes, and tamarillos, Fiji blocked tomatoes, capsicum and potatoes - and is now running short of spuds - and Japan also stopped key imports.

Overall tomato exports are worth $7.3 million annually and capsicum exports are worth $34 million. Growers are keen for constraints on exports to be lifted by October, when they are due to ramp up harvests from new crops they are now planting.

But now the Ministry of Agriculture and Forestry (MAF) has told growers that DNA tests developed in New Zealand show that the bacterium is in Texan potato crops, and is probably the cause of "zebra chip" disease which has been hitting American crops for years.

"The liberibacter detected in the USA is the same species as that detected in NZ," a MAF spokeswoman told NZPA.

Zebra chip converts part of the starch in a potato to soluble sugar, and when the potato is cooked, causes zebra-like stripes and breaks up the chip.

Spread by potato psillid insects - scientifically known as Bactericera cockerelli - the disease is thought to have been introduced to the US 15 years ago from Central America.

This insect also mysteriously turned up in New Zealand - found in an Auckland greenhouse in 2006 - and has since dispersed as far south as Nelson.

Zebra chip is a serious problem in regions such as Texas, particularly on species used for manufacture of french fries, and New Zealand technology companies have supplied American growers with NIR (or near-infrared) scanners to screen out affected potatoes.

MAF said it had provided American researchers with genetic markers for the bacteria and two laboratories detected it in Texas, in russet norkota potatoes showing zebra chip symptoms. The US has not reported the bacteria causing problems in tomatoes.

The identification means that trade officials re-negotiating access for NZ fruit and vegetables to overseas markets are no longer dealing with an unknown disease - they have been able to tell customer countries that the bacteria is probably the cause of zebra chip.

MAF said that after the announcement that the mystery bacteria was likely being spread by potato psyllids, it was first told of zebra chip symptoms in domestic potato crops.

Symptoms resembling zebra chip showed up in potatoes harvested from a breeding trial in South Auckland in May.

"These potato tubers tested positive for Liberibacter and was our first report of such in potatoes in NZ," the MAF spokeswoman said.

Potato psyllids feeding on spuds weakly infected with zebra chip spread the bacteria to other potato plants. American experts said that controlling the potato psyllids and planting seed potatoes certified free of zebra chip can reduce the spread.


Bacterial Ring Rot of Potato

Bacterial ring rot disease of potato is not known to occur in British Columbia. Occasional outbreaks in home gardens and table stock fields over the years have been detected and eradicated. The disease can be prevented by planting only "B.C. Certified" seed potatoes and not using table potatoes for seed or bringing in seed potatoes from outside the province. All potato growers in B.C. are asked to be aware of the symptoms of the disease and report any suspicious tubers to the British Columbia Ministry of Agriculture and Lands.

Ring rot is caused by a bacterium called Clavibacter michiganense subsp. sepedonicus. It causes disease only on potatoes.

The disease is called "ring rot" because the rot appears in the vascular ring of the potato tuber. In severely affected tubers, the vascular ring is brown to black in colour, often with a cheesy or creamy ooze and many hollow spaces where the flesh has disintegrated. Dry cracks can usually be found on the surface of the tubers. In milder cases, the vascular ring may show only broken, black lines or a yellowish discolouration. Leaves of infected plants may show interveinal yellowing, wilting, or no symptoms.

bacterial ring rot infected tubers    Bacterial ring rot infected tubers
   External tuber symptoms of bacterial ring rot.  Photo courtesy Dr. Solke De Boer, Canadian Food Inspection Agency
   Leaf symptoms of bacterial ring rot. Photo courtesy Dr. Solke De Boer, Canadian Food Inspection Agency
Survival and Spread:

Once a crop or farm is infested with the bacteria, the disease will carry over from year to year and spread quickly. The bacteria can survive for 2 to 5 years in dried slime on the surface of machinery, crates, bins or burlap sacking, even if frozen. Volunteer potato plants and plant debris, including infected cull tubers will also carry the bacteria overwinter. The bacteria can be spread in rain and irrigation water and by insects, but wounds are needed for infection. Thus, the most important means of infection is cutting seed potatoes with contaminated knives.

Prevention: Plant only B.C. Certified seed potatoes. Avoid using table stock for seed or importing seed from other areas for planting in BC. Disinfect knives frequently while cutting seed pieces, to avoid spreading any disease that might be present but unnoticed. Bury cull piles and control volunteer potatoes. Clean and disinfect storage bins between crops and pressure-wash equipment to avoid spreading ring rot or other diseases.

Control: If symptoms are seen or the disease is suspected, please notify the B.C. Ministry of Agriculture and Lands as soon as possible. Samples will be tested in the laboratory to confirm the disease and trace the source of the outbreak to prevent further spread. Ministry staff will advise on clean-up and disposal and will do follow-up testing to ensure that the disease has been eradicated. Please help protect our B.C. potatoes.

Regulations:  Bacterial ring rot is a regulated disease in British Columbia. All potatoes grown in British Columbia are covered under Domestic Bacterial Ring Rot Regulation 93/59. Under this regulation, if symptoms of bacterial ring rot are found in any potato crop grown in British Columbia, the occurrence must be reported to the provincial Ministry of Agriculture and Lands, and the crop must be detained until inspected. Bacterial Ring Rot Regulation 92/59 provides for inspection of all potatoes imported to British Columbia.


More on Ralstonia solanacearum: Bacteria Wilt of Potato (Brown Rot)
Tomato, Pepper, Eggplant, Tobacco and Geranium
Author:    Michael Celetti - Plant Pathologist- Horticulture Crops Program Lead/OMAFRA
Creation Date:    11 June 2003
Last Reviewed:    11 June 2003

Ralstonia solanacearum is a soilborne bacterial pathogen that causes southern bacterial wilt in geraniums, is highly destructive to potatoes, and infects numerous other plants including tobacco, bean, beets, tomatoes, eggplant, and peppers.


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How would I identify starch-utilising bacteria?
« Reply #1 on: 26/08/2008 16:12:07 »


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