Palmaria algal strains and methods for their use

Details Palmaria algal strains and methods for their use Palmaria algal strains and methods for their use

2000-01-06

2001-07-10

Tate, Christopher R. (Department: 1651)

Chemistry: molecular biology and microbiology

Micro-organism, per se ; compositions thereof; proces of...

Algae, media therefor

C435S243000

Reexamination Certificate

active

06258588

ABSTRACT:

FIELD
The present invention concerns strains of algae, such as Palmaria cultivars having a growth rate and temperature tolerance greater than wild type algae, including Palmaria cultivars having a rosette morphology. The described Palmaria cultivars are useful for a variety of purposes including, but not limited to, feeding organisms. Methods for isolating and culturing these cultivars also are described and claimed.
BACKGROUND
Red macroalgae of the genus Palmaria generally are reddish brown in color with broad, flattened fronds. The fronds arise from a base, usually with a small stipe, and gradually expand to form simple or palmately divided fronds, often with marginal leaflets. The shape of wild type Palmaria fronds can vary from broad ovals to narrow linear segments, though the most common shape is the characteristic palmate form with branching finger-like extensions.
Palmaria palmata,
a particular Palmaria species, is a popular ingredient in natural cosmetics and skin care products and also is widely used for food. The species is not particularly palatable when fresh but, if dried carefully and rapidly, is one of the few seaweeds that tastes good.
Palmaria palmata
is popular in coastal communities of the North Atlantic, particularly Ireland, Scotland, Iceland, Norway, France and Eastern Canada.
Though popular as a human food, Palmaria traditionally has not been used for aquaculture—the agricultural production of marine and freshwater organisms—which is an important and growing industry in the United States. Crustaceans, fish, and shellfish offer a high-protein food source as an alternative to beef, pork, and chicken products. While aquaculture production of crustaceans (such as shrimp and crawfish) or fish (such as baitfish or catfish) is a long-established industry, recent attention has been directed to the aquaculture of abalone.
Abalone is a gastropod, similar to oysters and clams, and is considered a gourmet delicacy. Aquaculture of abalone traditionally has been based on feeding abalone a diet of giant kelp (Macrocystis species) or bull kelp (
Nereocystis luetkeana
) harvested from wild kelp beds growing naturally in coastal areas. Giant and bull kelps are not an optimal abalone fodder (food source) for aquaculture operations, however. Like most marine algae, such kelps have relatively poor nutritional values and relatively high moisture contents, characteristics which make them poor food sources for abalone. Abalone consuming giant and bull kelps ingest a large amount of water and a low amount of usable food material, and thus exhibit relatively slow growth rates per amount of food consumed. For example, Ebert and Houk reported that bull kelp supports relatively slow abalone growth rates, typically a 30 to 60 &mgr;m shell length (SL) increase per day.
Abalone Cultivation Methods Used at the California Department of Fish and Game's Marine Resources Laboratory,
in HANDBOOK OF CULTURE OF ABALONE AND OTHER MARINE GASTROPODS, 242 (K. Hahn ed., 1989). These growth rate figures were later confirmed by Trevelyan et al.,
Increasing the yield of red abalone with the alga, Microcladia coulteri,
17 J. SHELLFISH RES. 631 (1998). Slow abalone growth rates and low feeding efficiency (rate of growth per amount of food consumed) of abalone decrease the economic efficiency and profitability of abalone aquaculture operations.
Even though kelps, such as giant and bull kelps, have poor nutritional value for abalone, their abundance in the abalone's natural habitat and the soft texture of their fronds may explain why they have been used as abalone fodder in aquaculture operations. P. E. McShane et al.,
Factors influencing food selection in the abalone Haliotis rubra
(
Mollusca: Gastropoda
), 176 J. EXP. MAR. BIOL. ECOL. 27 (1994). The abalone aquaculture industry is also located particularly in Pacific coastal areas that support an abundance of giant and bull kelps suitable as abalone fodder. The geographic expansion of the abalone industry is limited to sites where such kelps can be easily harvested in sufficiently large quantities to support land-based and offshore abalone farms. E. E. Ebert,
Abalone aquaculture: a North America regional review,
in ABALONE OF THE WORLD 570 (S. A. Shepherd et al. eds., 1992). Additionally, governmental regulations and natural events, such as El Nino, affect the use, distribution, and availability of such kelps for harvest. J. P. Mercer et al.,
General principles of on-shore cultivation of seaweeds: effects of light on production,
221 HYDROBIOLOGIA 125 (1993); S. C. McBride,
Current status of abalone aquaculture in the Californias,
17 J. SHELLFISH RES. 593 (1998); Ebert, (1992). For these reasons, the U.S. abalone aquaculture industry historically has been limited to the natural geographical locations of giant kelp (Macrocystis species) or bull kelp (
Nereocystis luetkeana
), primarily California. If a different food source for abalone were available, abalone aquaculture could spread geographically into other regions.
Moreover, commercial aquaculture operations must consider economic factors and comply with environmental regulations to harvest large quantities of kelp. For example, traditional land-based abalone farms maintain water quality via rapid water volume exchange rates, which flush abalone waste products (e.g. ammonia, nitrates, carbon dioxide, and dissolved organic wastes) from the culture system. These waste products must be processed into more environmentally benign materials to avoid polluting the environment. More environmentally sound aquaculture methods, or improved methods for controlling and processing abalone waste products, would therefore allow aquaculture operations to become more expansive and profitable.
SUMMARY
The present invention addresses the needs described above. Methods for isolating rapidly growing
Palmaria mollis
(dulse) strains for a variety of uses, including alternative food sources for humans and abalone, are described. The isolated strains have a growth rate greater than that of wild type Palmaria, and known strains of Palmaria, at a temperature of about 16° C. or greater. The rosette morphologies of certain strains provide a greater surface area to volume (SA/V ratio) than wild type Palmaria, and other known strains. This greater SA/V ratio exposes more of the algae to sunlight, thus allowing the strains of the present invention to be more photosynthetically active than the wild type or known strains, and exposes more of the algae to aquatic environments, thus allowing greater absorption of nutrients and organic carbon.
The greater SA/V ratio also exposes more of the alga's surface to the air, thus allowing more rapid evaporation of water from and desiccation of the alga. The Palmaria strains of the present invention can therefore be more rapidly dried for human consumption. Additionally, because of the rosette morphology, some strains have small, thin, leafy fronds, much like parsley (rather than having the large, thick fronds of the wild type Palmaria), which may make such strains more palatable for human consumption when fresh. The rapid growth rate also allows greater production of the claimed strains for use as food in aquaculture, such as in abalone aquaculture operations. Some isolated strains are capable of co-culturing with abalone, which aids in the elimination of abalone wastes, thus avoiding at least some costs of complying with environmental regulations.
Certain embodiments of the present invention comprise Palmaria algae having a growth rate greater than wild type Palmaria, or known strains, at a water temperature of 16° C. or greater, such as a specific growth rate of at least 8% per day at a stocking density (SD) under working conditions. The “working conditions” of the present invention are described in more detail below.
Particular
Palmaria mollis
strains having these characteristics have been isolated, including strains having a rosette morphology. Preferred Palmaria algae are reproductively sterile. An example of a particular
Palmaria mollis
strain having the

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